If you follow medical news, you know the gut microbiome is largely responsible for your overall health. Amazing, isn’t it? Hippocrates was right! After reviewing the ins and outs of the gut microbiome, I’ll get into gut health supplements and recommend the best gut microbiome test. Here’s what I’ll cover.

  • What is the gut microbiome?.
  • Gut microbiome components
  • How the gut microbiome works
  • Functions of a healthy gut microbiome
  • Normal versus abnormal gut microbiome
  • Prebiotics
  • Benefits and specifics of Prebiotics
  • Prebiotic Fibers
  • Prebiotic Oligosaccharides
  • Galacto-oligosaccharides
  • Resistant Starch
  • Polyphenols
  • Flavonoid Polyphenols
  • Other Flavonoid Polyphenols
  • Hydroxycinnamic Acids
  • Probiotics
  • Synbiotics
  • Postbiotics=Paraprobiotics=Ghostbiotics
  • Beneficial gut microbiome byproducts
  • Short-chain Fatty Acids
  • SCFA production in commensal(host) and probiotic strains of bacteria
  • Butyrate and gut health
  • Butyrate and the gut-brain barrier
  • Butyrate and Aging
  • Propionic acid (Propionate)
  • Acetate
  • Acetate from Dietary Sources
  • What Shapes the Adult Microbiome?
  • Healthiest Microbiome Diet
  • Foods that promote inflammation= avoid
  • Anti-inflammatory foods
  • Best gut microbiome supplements
  • Best microbiome test=microbiome labs (Yes, there’s an app for it!)


What is the Gut Microbiome?

The gut microbiome is a complex ecosystem comprising trillions of microorganisms, including bacteria, fungi, and viruses (specifically bacteriophages). These microorganisms and their genes collectively make up the gut microbiome.

Bacteriophages, or the “virome,” are viruses that specifically infect and replicate within bacteria. Interestingly, they outnumber gut bacteria and help shape the composition of the gut bacterial communities.

On the other hand, Fungi make up a smaller portion of the gut microbiome, known as the “mycobiome.” Candida is a prevalent genus of fungi in this microbiome.

Understanding the composition and dynamics of the gut microbiome, including these various components, is an active area of research as it has implications for our overall health and well-being.

The gut microbiome’s organisms are categorized into various taxonomic levels, including phyla, classes, orders, families, genera, and species. These taxonomic classifications help researchers understand the diversity and structure of microbial communities in the gut.

The gut microbiota can vary among individuals, and differences in the abundance of specific phyla can significantly impact health. The four dominant phyla commonly found in the gut microbiome are Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria. Firmicutes and Bacteroidetes comprise around 90% of the gut microbiota.

Within the Firmicutes phylum, the Clostridium genus is particularly abundant, representing a large percentage of this group. Other genera within Firmicutes, such as Lactobacillus, Bacillus, Enterococcus, and Ruminicoccus, also play essential roles in the gut microbiome.

Understanding the distribution and abundance of these different taxonomic groups within the gut microbiome is crucial for studying their functions and potential impacts on human health.

While the focus has often been on bacteria in the gut microbiome, research has shown that both the mycobiome and virome can also play important roles in gut health.

The mycobiome, or fungal community in the gut, can be influenced by various factors, including diet and environmental factors. Dysbiosis or imbalances in the mycobiome have been associated with some immunodeficiency states and inflammatory disorders, such as Inflammatory Bowel Disease (IBD).

For example, specific fungal cell wall epitopes, such as anti-Saccharomyces cerevisiae antibodies (ASCA), have been found to be a biomarker for Crohn’s disease and are cross-reactive with the fungus Candida albicans.

Antibiotic use can also affect the balance of the mycobiome and lead to the overgrowth of certain fungi in the gut. We’ll discuss this later on in this article.

Overall, the mycobiome is an essential component of the gut microbiome, and its contribution to gut health is an active area of research.

The virome, composed chiefly of bacteriophages, is a highly diverse biological system within the gut. Bacteriophages are viruses that specifically infect bacterial cells, and their presence and activity can directly impact the immune system.

Bacteriophages can influence the immune system by stimulating the production of specific immune molecules, such as interleukin-1b and tumor necrosis factor-alpha, by macrophages. These molecules are involved in immune responses and inflammation.

Additionally, the gut virome is responsive to changes in diet. Different dietary compositions can influence the abundance and activity of specific bacteriophages within the gut.

In the next section, we’ll discuss the “gut bugs” populations found in each section of the gastrointestinal (GI) tract.

Understanding the population dynamics and functions of gut bacteria in different sections of the GI tract is crucial for comprehending their roles in digestion, nutrient metabolism, immune function, and overall gut health.

Gut Microbiome Components

The microbiota composition varies along the length of the gastrointestinal tract, from the mouth to the colon.

The colon, specifically the large intestine, harbors the highest density and diversity of bacteria in the gut. This is primarily due to increased nutrient availability (such as undigested dietary fibers) and slower material transit time through the colon. The colon’s lower pH also favors certain bacterial species’ growth.

In contrast, the small intestine generally has a lower abundance and diversity of microbiota than the colon. Several reasons contribute to this difference. Firstly, the transit time in the small intestine is relatively faster, allowing less time for the bacteria to colonize and establish. Additionally, the small intestine is exposed to the influx of digestive enzymes and bile from the liver, which can impact the growth and survival of certain bacterial species. Lastly, food substrates are delivered intermittently to the small intestine, further limiting the availability of nutrients for bacterial growth.

It’s important to note that even though the small intestine has a lower bacterial population, it still plays a crucial role in the digestion and absorption of nutrients.

Understanding these regional differences in the composition and function of the gut microbiota is essential for unraveling their contributions to overall gastrointestinal health and metabolic processes.

The human oral cavity harbors a diverse and abundant microbial community known as the oral microbiome. This microbiome typically exists in the form of a biofilm, commonly called dental plaque.

The oral microbiome includes various bacteria, such as Streptococcus mutans, Porphyromonas gingivalis, Staphylococcus, and Lactobacillus. Streptococcus mutans is a prominent component of the oral microbiota and is strongly associated with the formation of dental plaque and tooth decay (caries). It can metabolize sugars, produce acid, and contribute to the demineralization of tooth enamel.

Lactobacillus is another bacterium in the oral microbiome that can ferment sugar and produce lactic acid. This acid can also contribute to the development of dental caries.

Beyond oral diseases like caries and periodontitis, the oral microbiome has been linked to several systemic diseases. Research has found associations between oral microbiota and conditions such as esophageal, colorectal, and pancreatic cancers, diabetes, Alzheimer’s disease, cardiovascular disease, cystic fibrosis, and rheumatoid arthritis.

However, it’s important to note that these associations do not necessarily imply causation, and further research is needed to fully understand the complex relationship between the oral microbiome and systemic diseases.

Interestingly, the oral microbiome can also be targeted for disease treatment. Probiotics, such as a particular strain of Streptococcus called Streptococcus A12, have been investigated for their ability to buffer the acidic pH within biofilms. This buffering effect may help prevent dental caries caused by acid-producing bacteria in the oral microbiome.

Understanding the composition, dynamics, and interactions within the oral microbiome is crucial for maintaining oral health, preventing oral diseases, and potentially influencing systemic health.

While the esophagus has its distinct microbiome, that is beyond the scope of this discussion. Moving on to the stomach, let’s discuss the basics.

The human stomach harbors a diverse array of microbes, with five major phyla dominating the microbial population: Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, and Proteobacteria. At the genera level, certain microbial genera are particularly prevalent in the stomach microbiome. These include Prevotella, Streptococcus, Veillonella, Rothia, and Haemophilus, among the most common genera in the gastric environment.

Observing the intricate composition of the human stomach microbiome and the key players contributing to its microbial diversity is fascinating. Understanding the role of these significant phyla and genera in the stomach microbiota is crucial for unraveling the complexities of digestive health and disease susceptibility.

Several factors influence the composition and diversity of the gastric microbiota, including diet, medication usage, inflammation, and Helicobacter pylori infection.

Diet: Dietary patterns and nutrient composition can affect the microbial composition of the stomach. Studies have shown that diets high in fruits, vegetables, and fiber are associated with a more diverse and stable gastric microbiome. In contrast, diets high in fat and sugar can disrupt the microbial balance in the stomach and promote the growth of potentially harmful bacteria.

Medication Usage: Medications such as proton pump inhibitors (PPIs) and antibiotics can significantly affect the gastric microbiota. PPIs work by reducing stomach acid production, which can alter the stomach’s environment and affect the growth of certain bacteria. Antibiotics, conversely, can cause extensive changes in the gastric microbiota by eliminating harmful and beneficial bacteria and allowing opportunistic pathogens to colonize.

Inflammation and Gastric Mucosa: Inflammation of the gastric mucosa and atrophic gastritis can also impact the composition of the gastric microbiota. Chronic inflammation can decrease microbial diversity, promote the growth of pathogenic bacteria, and cause imbalances in the stomach microbial community.

Helicobacter pylori Infection: Helicobacter pylori infection is one of the most significant factors affecting the gastric microbiota. H. pylori is a Gram-negative bacterium that colonizes the stomach mucosa, and its presence can cause a range of gastric conditions, including gastritis, peptic ulcers, and gastric cancer. H. pylori has been shown to alter the gastric microbiota by reducing microbial diversity and increasing the numbers of certain bacterial species.

Understanding the factors influencing the gastric microbiota is essential for developing strategies to promote a healthy microbial community and prevent or treat gastric diseases.

The small intestine is the most extended section of the gastrointestinal (GI) tract and has its own microbiome. Its microbial composition differs from that of the stomach and colon. Some bacterial genera commonly found in the small intestine include Lactobacillus, Clostridium, Staphylococcus, Streptococcus, and Bacteroides.

The population of bacteria in the small intestine increases as you move from the duodenum (the first part of the small intestine) to the distal ileum (the last part before the large intestine). The bacterial counts in the duodenum range from around 104-105 colony-forming units (CFU) per milliliter, while in the distal ileum, where transit slows down, the counts increase to 107-108 CFU/mL.

The composition of the small intestinal microbiota also changes gradually along the length of the small intestine. There is an increase in the proportion of gram-positive bacteria compared to gram-negative bacteria, as well as a shift from facultative anaerobic (oxygen-tolerant) to strict anaerobic species.

Small Intestinal Bacterial Overgrowth (SIBO) is a condition characterized by excessive bacteria within the small intestine. This overgrowth can disrupt the normal digestion and absorption processes, causing abnormal fermentation of nutrients and leading to symptoms such as excessive gas, bloating, diarrhea, and malabsorption.

SIBO has been linked to various conditions, with up to 78% of irritable bowel syndrome (IBS) cases being associated with SIBO.

It’s interesting to note that hormonal deficiencies can contribute to the development of SIBO. Hormones play a crucial role in regulating gut motility and maintaining the balance of gut bacteria. Any disruption in hormonal levels can affect food movement through the GI tract and promote the growth of bacteria in the small intestine.

Indeed, the various aspects of our health, including gut health and hormonal balance, are interconnected, and disruptions in one area can impact others. Understanding the role of the small intestine microbiome and conditions like SIBO can help develop effective treatments and maintain overall health. Now, let’s talk about the section of the G.I. tract where much of the “action” is: the colon.

The colon, also known as the large intestine, houses the most diverse and abundant microbiome in the human gastrointestinal tract. This microbiome is composed mainly of obligate anaerobes, which thrive in the colon’s low-oxygen environment.

Among the most abundant bacteria in the colon are members of the genus Bacteroides and anaerobic gram-positive cocci like Peptostreptococcus, Eubacterium, Lactobacillus, and Clostridium.

The colonic microflora plays a vital role in various host digestive processes. One of its primary functions is the fermentation of non-digestible carbohydrates, including dietary fibers that escape digestion in the upper gastrointestinal tract.

The colonic bacteria break down these fibers through fermentation, producing several beneficial byproducts, such as short-chain fatty acids (SCFAs). SCFAs, mainly acetate, propionate, and butyrate, are important energy sources for the colonic epithelial cells and contribute to overall colon health.

The gut microbiome is also involved in other essential functions, including:

  1. Nutrient metabolism: The colonic bacteria metabolize certain compounds that the host cannot digest, such as complex polysaccharides, proteins, and bile acids. The microbiome can influence nutrient availability and absorption in the host through these metabolic processes.
  2. Vitamin synthesis: Some colon bacteria can produce vitamins, such as vitamin K and specific B vitamins. These microbial-synthesized vitamins can contribute to the host’s vitamin status and play essential roles in various physiological processes.
  3. Immune modulation: The gut microbiome interacts with the host immune system, helping to educate and shape its development. The microbial community in the colon can regulate immune responses, promote immune tolerance, and protect against potential pathogens.

Many studies on the gut microbiome rely on analyzing fecal samples to study the luminal “fecal” colonic microbiome. Fecal samples provide valuable insights into the overall composition and functions of the colonic microbiota.

However, it’s worth noting that there are also colonic-adherent microbiota that interact more directly with the host immune system. These adherent microbes require sampling through intestinal biopsies during procedures like colonoscopy to study their specific interactions with the host.

Understanding the functioning of the gut microbiome is a complex and evolving field of research. Ongoing studies uncover the intricate roles of the colonic microbiota in human health and disease.

How the gut microbiome works

Yes, it is true that approximately ten times as many microbial organisms inhabit our bodies as there are human cells. These microbes colonize various body parts, including the gut, digestive tract, genitals, mouth, and nose.

The health of someone’s microbiome is determined by the balance between “bad bacteria” and “good bacteria.” A healthy microbiome requires a higher ratio of beneficial to harmful bacteria to maintain resilience and stay symptom-free.

Unfortunately, factors such as a poor diet, high levels of stress, and exposure to environmental toxins can disrupt this balance, leading to an overabundance of potentially dangerous bacteria, fungi, yeast, and pathogens.

Although the human microbiome is home to various types of microorganisms, bacteria have been found to play a vital role in controlling immune function and inflammation. Researchers have identified over 10,000 different species of microbes in the human body, each with unique DNA and specific functions.

Maintaining a healthy balance of bacteria in the microbiome is crucial for overall health and well-being. Promoting diversity and abundance of beneficial bacteria through a balanced diet, reducing stress levels, and minimizing exposure to toxins can help support a healthy microbiome and its associated functions.

Indeed, researchers are still uncovering the many ways that different strains of bacteria affect various aspects of human health. Even so, some general characteristics of a healthy versus unhealthy microbiome have emerged in existing research.

A healthy microbiome is typically characterized by a high diversity of bacterial species, with a balance between “good” and “bad” bacteria. Additionally, it generally is more stable and resilient, able to resist changes in response to various factors such as diet, stress, and environmental toxins.

Conversely, an unhealthy microbiome is often characterized by a lower diversity of bacterial species and an overgrowth of pathogenic or “bad” bacteria. These imbalances in the microbiome have been associated with various health conditions, including obesity, autoimmune disorders, cognitive decline, and inflammation.

In summary, a healthy microbiome is diverse, balanced, and stable, while an unhealthy microbiome lacks these qualities. Ongoing research will likely uncover additional factors contributing to microbiome health and disease. Here are the basic functions of the microbiome.

Functions of a Healthy Gut Microbiome

As you know, the gut microbiome profoundly impacts our overall health and plays a vital role in various physiological processes. Here are some additional points to consider:

  1. Mucosal homeostasis and immune cell modulation: The gut microbiome helps maintain the balance and function of immune cells in the gut mucosa. It promotes immune cell development, regulates immune responses, and supports the integrity of the gut lining.
  2. Vitamin synthesis: Some beneficial bacteria in the gut can synthesize specific vitamins, such as vitamin K and many B vitamins. These vitamins are essential for various physiological processes in the body.
  3. Influence on gastrointestinal hormones: The gut microbiome can impact the production and response to gastrointestinal hormones, such as ghrelin and leptin, which are involved in appetite regulation and metabolism.
  4. Maintenance of intestinal homeostasis: The gut microbiome helps maintain a healthy environment in the intestines by regulating factors such as pH levels, bile acid metabolism, and nutrient absorption. This contributes to the overall balance and proper functioning of the digestive system.
  5. Regulation of epithelial cell proliferation and differentiation: The gut microbiome influences the growth, proliferation, and differentiation of epithelial cells that line the intestinal wall. This is crucial for maintaining a healthy gut barrier and proper nutrient absorption.
  6. Prevention of pathogenic colonization: Beneficial bacteria in the gut compete with and prevent the colonization of pathogenic microorganisms. They help maintain a balanced microbial community and reduce the risk of infections or overgrowth by harmful bacteria.

So, what is “normal?”

Normal Versus Abnormal Gut Microbiome

A healthy microbiome begins to form from birth and develops during early childhood. By age 3, a person’s microbiome closely resembles an adult’s. However, the microbiome continues to evolve throughout life, adapting to changes in diet, lifestyle, and other factors.

While the relative abundances of different microbial species can fluctuate, the overall community and function of the microbiome remain relatively stable and healthy. This stability allows the microbiome to perform important functions, such as synthesizing specific vitamins, aiding digestion, and supporting immune function.

On the other hand, an unhealthy microbiome can also be stable, leading to chronic disease. The concept of resilience is crucial in understanding the impact of disturbances on the microbiome. A resilient microbiome can withstand temporary disruptions, such as a single course of antibiotics, and return to its original state.

However, persistent interferences, like long-term changes in diet, recurrent antibiotic use, or disruptions during vulnerable periods (such as infancy or the peripartum period), can create a new, disease-promoting state in the microbiome.

It’s important to note that the relationship between the microbiome and specific diseases is still an active area of research, and more studies are needed to fully understand the complex interactions. However, maintaining a diverse and resilient microbiome through a balanced diet, healthy lifestyle choices and judicious (sparing) use of medications may support overall gut health.

There are specifically known indicators of a healthy gut microbiome. For example, gut microbiome alpha diversity (diversity in one sample) has been linked to positive human health, while lower levels of diversity are associated with several acute and chronic diseases. Another well-known marker is the Firmicutes to Bacteroidetes (F/B) ratio.

In addition, several particular bacterial species have been recognized for their benefits, such as Faecalibacterium prausnitzii. F. prausnitzii has been consistently reported as one of the primary butyrate producers in the gut, with the ability to reduce gut mucosal inflammation and protect against both colorectal cancer and inflammatory bowel disease. We’ll get “heavily” into the importance of butyrate and other vital fatty acids.

Another important bacterium is Akkermansia muciniphilaA. muciniphilia has been shown to contribute to the maintenance of a healthy gut barrier, regulate immunity, and modulate inflammation. Notably, a lower abundance of this organism has been associated with multiple diseases.

If you are reading this article, chances are you’ve read other articles about the gut microbiome. And perhaps you’ve been as confused as everyone else over the gut microbiome terminology. Let me clarify all of this terminology for you so you know what’s what moving forward. Let’s first discuss the terminology of the gut microbiome and gut health supplements.


Prebiotics are defined as “selectively fermented ingredients that result in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health.”

The original definition of prebiotics, established in 1995, described these compounds as non-digestible food ingredients that play a crucial role in influencing the growth and activity of specific bacteria in the colon. By selectively stimulating the proliferation of one or a limited number of beneficial bacterial species, prebiotics were believed to enhance host health through their interactions with the gut microbiota.

The updated definition of prebiotics in 2004 introduced three critical criteria to refine the classification further. According to this revised definition, prebiotics should meet the following requirements:

Resistant to Gastric Acidity and Hydrolysis: Prebiotics must demonstrate resistance to gastric acidity, enzymatic hydrolysis by mammalian enzymes, and absorption in the gastrointestinal tract to reach the colon.

Fermented by Intestinal Microbiota: Prebiotics should be fermentable by the intestinal microbiota, indicating their ability to undergo microbial metabolism in the gut environment.

Selective Stimulation of Beneficial Bacteria: Prebiotics must selectively stimulate intestinal bacteria’s growth and/or activity associated with health and well-being, emphasizing their role in promoting the proliferation of beneficial microbial species in the gut.

Now for the benefits and more specifics.

Benefits and specifics of Prebiotics

Prebiotics can modify the gastrointestinal microbiota through dietary strategies for potential health benefits. Studies have shown that increased intake of dietary fiber, particularly fermentable fiber, can promote the growth and diversity of beneficial gut bacteria, leading to improved gut health and reduced risk of chronic diseases.

Low fiber intake, prevalent in Western societies, has been linked to impaired gut microbiota with reduced diversity and an overgrowth of potentially harmful bacterial species. This may contribute to the development of chronic non-communicable diseases, including obesity, cardiovascular disease, type 2 diabetes, and colon cancer.

Intervention studies in humans have also demonstrated that increasing dietary fiber and whole grains intake can increase gut bacterial diversity, highlighting the importance of a high-fiber diet for maintaining a healthy gut microbiome.

Therefore, prebiotic-rich foods such as whole grains, fruits, vegetables, and legumes can be an effective dietary strategy to promote gut health and potentially prevent chronic diseases.

Prebiotic Fibers

According to the definition provided by the Codex Alimentarius Commission in 2009, dietary fibers are described as “carbohydrate polymers with ten or more monomeric units, which are neither digested nor absorbed in the human small intestine,” and they fall into three categories:

  1. Edible carbohydrate polymers naturally occurring in foods as consumed.
  2. Edible carbohydrate polymers obtained from food raw materials through physical, enzymatic, or chemical means have a beneficial physiological effect supported by generally accepted scientific evidence.
  3. Generally accepted scientific evidence supports Edible synthetic carbohydrate polymers with a demonstrated beneficial physiological effect.

This definition recognizes the diverse range of dietary fibers in natural foods and those obtained through various processing methods. It emphasizes that these carbohydrates should resist digestion and absorption in the small intestine and have scientifically demonstrated health benefits.

Indeed, plant-based fibers can be classified into various categories based on their origin, such as cereals and grains, fruits, vegetables, nuts, and legumes. It is important to note that different types of plants contain different fibers with distinct chemical compositions and physicochemical properties.

For example, bananas contain resistant starch and inulin-type fructans, which are prebiotic fibers that can promote the growth of beneficial gut bacteria. On the other hand, apples are a good source of pectin, another dietary fiber with health benefits.

Diets rich in various plant-based foods can provide a wide range of dietary fibers, thus supporting the diversification of the gut microbiota. The different types of fibers in these foods can selectively stimulate the growth of beneficial bacteria in the gastrointestinal tract, leading to a more diverse and balanced microbiota composition.

Therefore, consuming diverse plant-based foods can contribute to a healthier gut microbiome and overall gut health.

The microbial conversion of complex polysaccharides into monosaccharides involves a variety of biochemical pathways, which are facilitated by the enzymatic activities of bacteria in the gut.

When complex carbohydrates, such as dietary fibers, reach the colon, gut bacteria ferment them. The end products of this fermentation process include short-chain fatty acids (SCFAs) and gases such as hydrogen (H2) and carbon dioxide (CO2).

SCFAs, namely acetate, propionate, and butyrate, are the primary products of bacterial fermentation in the colon. These SCFAs are crucial in maintaining gut health and have several beneficial effects on the host.

SCFAs serve as an energy source for colonocytes, promote sodium and water absorption, and help regulate the colon’s pH. They also have immunomodulatory properties and can influence various body processes, including inflammation and metabolism.

The proportions of SCFAs produced during fermentation can vary based on the types of carbohydrates ingested and the gut microbiota composition. Different bacteria have different metabolic capabilities, which can result in variations in the production and ratios of SCFAs among individuals.

Therefore, measuring SCFAs in the colon can provide valuable information about bacterial fermentation and the health status of the gut microbiota.

Prebiotic Oligosaccharides

A regular diet typically contains various prebiotic oligosaccharide carbohydrates, including inulin-type fructans. Inulin-type fructans naturally occur in foods such as chicory root, Jerusalem artichoke, garlic, and certain cereals like wheat.

It is important to note that inulin-type fructans in foods can contribute to their prebiotic effects. Prebiotics are non-digestible dietary fibers that promote the growth and activity of beneficial bacteria in the gut, thus supporting gut health.

Inulin-type fructans, specifically, have been shown to selectively stimulate the growth of Bifidobacteria and Lactobacilli, which are considered beneficial bacteria in the gut microbiota. Remember that wheat grown in the U.S. may be problematic for many people, so watch out for GMOs and gluten.


These diary-derived prebiotics have potential immune-modulating effects. Beta-galacto-oligosaccharides are prebiotic dietary fiber that can benefit the gut microbiota and immune system.

In a well-done study conducted on elderly subjects, supplementation with β-GOS was shown to have several positive effects on immune function. Some key findings from the study include:

Increased levels of the immuno-regulatory cytokine interleukin-10 (IL-10) regulate the immune response and reduce inflammation.

Significant reduction in the expression of IL-1β, a pro-inflammatory cytokine associated with the inflammatory response.

Increased interleukin-8 (IL-8) blood levels are involved in immune cell recruitment and activation.

Improvement in Natural Killer (NK) cell activity is vital for the body’s defense against viruses and cancer cells. Next, let’s move on to something you probably have heard about called resistant starch.

Resistant Starch

Resistant starch (RS) is naturally present in cereal grains and other starch-containing foods. It refers to a type of starch that resists digestion in the small intestine and reaches the large intestine intact. The resistance to digestion can be influenced by factors such as granule morphology, amylose-amylopectin ratio, and interactions with other food components.

RS is classified into four classes based on its digestibility. These classes help categorize the different types of RS based on their resistance to digestion and their impact on gut health.

One interesting study demonstrated that RS has a bifidogenic effect, meaning it increases the concentration of beneficial bacteria such as Bifidobacteria.

It also increased the levels of other beneficial bacteria, including Bacteroidetes, Akkermansia, and Allobaculum species. These bacteria are essential in maintaining gut health and promoting a balanced gut microbiota.

Furthermore, studies conducted in vitro and on mice have shown that resistant starch increases the production of short-chain fatty acids (SCFAs).

SCFAs are beneficial compounds gut bacteria produce during dietary fiber fermentation, including RS. SCFAs have several health benefits, such as providing energy for colonocytes, promoting gut health, and influencing various physiological processes.

While there are limited studies on humans, some evidence suggests that high amylose maize starch (HAMS) administration, a type of resistant starch, may have prebiotic effects in adults.

Other examples of resistant starch include cooked and cooled pasta and rice, oats, green bananas, certain legumes, and raw potato starch. For my extensive practice of autoimmune patients eating strict AIP, the best choice is green bananas.


The primary sources of polyphenols are fruits such as berries, grapes, citrus fruits, apricots, apples, plums, cherries, peaches, and tropical fruits. Additionally, polyphenols can be found in popular beverages such as green and black tea, fruit juices, coffee, red wine, cocoa, and beer, as well as in various seeds, grains, and nuts.

Vegetables are also a good source of polyphenols, with onions, spinach, broccoli, cauliflower, artichoke, tomato, beans, soybeans, carrots, capers, and olives being some of the most common sources. Even spices and herbs such as clove bud, turmeric, celery, parsley, mint, rosemary, thyme, sage, dill, curry, and ginger contain high levels of polyphenols.

Polyphenols are a diverse group of compounds, and their concentration and type can vary widely depending on the food source. However, a diet rich in fruits, vegetables, nuts, and whole grains is generally associated with a high intake of polyphenols and other beneficial phytochemicals.

Polyphenols have numerous health benefits, including antioxidant and anti-inflammatory effects. Some studies have suggested they may protect against chronic diseases such as cardiovascular disease, type 2 diabetes, and certain cancers.

Flavonoid Polyphenols

Flavonoids are a major class of dietary polyphenols, constituting up to 60% of polyphenol intake. Due to their widespread presence in various foods and impressive biological functions and activities, flavonoids are continuously being studied for their potential as drugs or food supplements.

Some of the most common flavonoids include:

  1. Quercetin: This flavanol is abundant in foods such as onions, broccoli, tea, and apples. Quercetin is known for its antioxidant and anti-inflammatory properties.
  2. Catechin: A flavanol found in tea (mainly green tea) and various fruits, catechin is recognized for its potential health benefits, such as cardiovascular protection and anticancer properties.
  3. Naringenin: A flavanone present in citrus fruits like oranges, grapefruits, and lemons, naringenin has been studied for its antioxidant and anti-inflammatory effects.
  4. Cyanidin and Anthocyanin: These flavonoids give fruits and berries such as blackcurrants, raspberries, strawberries, blueberries, and grapes their vibrant red, purple, or blue color. Anthocyanins have various health benefits, including cardiovascular health and improved cognitive function.
  5. Daidzein and Genistein: These are the main isoflavones found in soybeans and soy products. Isoflavones have been studied for their potential role in hormonal balance and reducing the risk of certain chronic diseases.

Other Flavonoid Polyphenols


  • Naturally occurring phytochemicals of the flavonoid class.
  • Referred to as “phytoestrogens” due to their estrogen-like effects.
  • Predominant sources are legumes, particularly soy products.
  • Commonly found in fermented soy foods like soy paste and unfermented soy products like tofu and soy flour.


Phenolic acids:

  • Found in leguminous plants, vegetables (spinach, broccoli, kale), berry fruits, apples, coffee, tea, citrus juices, wine, beer, cereal brans, and olive oil.
  • Provide substantial antioxidative and anticancer activities.

Hydroxybenzoic acids:

  • Simple aromatic acids with substantial antioxidative and anticancer activities.
  • Main representatives are gallic and ellagic acid, abundant in fruits and nuts.


  • Naturally occur as glycosides named anthocyanins.
  • Responsible for the red, purple, and blue hues of various fruits, vegetables, cereal grains, and flowers.
  • Main sources include teas, honey, wines, fruits (apples, berries), vegetables (beets, onions), nuts, olive oil, cocoa, and certain cereals.


  • Another important class of naturally occurring flavonoids.
  • Metabolic precursors of certain flavonoids and isoflavonoids.
  • Abundant in hops and, therefore, in beer, as well as citruses, apples, certain vegetables (shallots, tomatoes, potatoes, bean sprouts), and various plants and spices (licorice, cardamom).

Ellagic acid:

  • Dimeric derivative of gallic acid.
  • Richest sources include blackberries, raspberries, strawberries, cranberries, pomegranates, walnuts, and pecans.
  • Possesses anti-carcinogenic, antioxidant, anti-inflammatory, anti-bacterial, anti-atherosclerosis, anti-hyperglycemic, anti-hypertensive, anti-fibrosis, and cardioprotective effects.

Hydroxycinnamic Acids 

Cinnamic acid:

  • Acts as the precursor of hydroxycinnamic acids, a diverse group of phenolic substances present in almost every plant.
  • Common hydroxycinnamic acids include caffeic acid and ferulic acid.

Caffeic acid:

  • Found in many fruits such as apples, plums, tomatoes, and grapes.

Ferulic acid:

  • Found in tomatoes and beer in an accessible form, making it efficiently absorbed.
  • Also found in an esterified form in grain cell walls (in cereals).

Chlorogenic acid:

  • Another essential phenolic acid with varying intake levels.
  • Coffee drinkers can consume up to 800 mg per day of chlorogenic acid.

Honorable mentions include rosmarinic acids, curcuminoids, and stilbenes, which will be discussed below in the “supplements” section. Now, let’s switch our focus from prebiotics to probiotics.



Probiotics are live microorganisms that provide health benefits when consumed or applied to the body. They can be found in several sources, such as yogurt and other fermented foods, dietary supplements, and beauty products. Probiotics often contain bacteria from groups like Lactobacillus and Bifidobacterium, which are commonly used. In addition to bacteria, some probiotics may also include yeasts like Saccharomyces boulardii.

Different types of probiotics may have other effects. For example, suppose a specific kind of Lactobacillus helps prevent an illness. That doesn’t necessarily mean another type of Lactobacillus or Bifidobacterium probiotics would do the same thing.

Probiotics work through various mechanisms to exert their beneficial effects on the host. Here are the three primary mechanisms:

  1. Synergistic Effects with Indigenous Microbiota: Probiotics interact with the existing beneficial bacteria in the gut. This interaction helps promote a healthy balance of the gut microbiota. Probiotics can influence the production of short-chain fatty acids (SCFAs), which are essential for gut health. SCFAs provide energy for the colon cells, support maintaining the intestinal barrier function, and have anti-inflammatory properties. I’ll go into this in much greater depth shortly.
  2. Enhancement of Epithelial Barrier Integrity: Probiotics can strengthen the integrity of the epithelial barrier, which is the gut’s protective lining. By enhancing the barrier function, probiotics help prevent the passage of harmful substances from the gut into the bloodstream, reducing the risk of inflammation and other adverse health outcomes.
  3. Modulation of the Host’s Immune System: Probiotics can influence the immune system in the gut. They can help regulate immune responses, promoting a balanced and appropriate immune reaction. This modulation of the immune system can be beneficial in preventing and managing certain inflammatory conditions in the gut.

Additionally, probiotics have been found to affect electrolyte absorption, gut motility, and even the perception of painful sensations. These actions can further contribute to their overall beneficial impact on digestive health.

It’s important to note that the specific mechanisms of action may vary depending on the strain and probiotic used and the individual’s unique microbiome and health condition.

Now, let’s clarify what synbiotics, paraprobiotics, ghostbiotics, and postbiotics are. Whew, right? Let’s start with simple synbiotics.



Synbiotics are mixtures that consist of live microorganisms (probiotics) and substrates selectively utilized by host microorganisms (prebiotics) that provide a health benefit to the host. A symbiotic blend, which is what is commonly found for sale, typically contains a proven probiotic and a proven prebiotic.

There are two types of synbiotics: complementary and synergistic. A complementary synbiotic contains a live microorganism (which may or may not be a proven probiotic) and a substrate (which may or may not be a proven prebiotic). These components work together to provide a health benefit.

On the other hand, a synergistic synbiotic consists of a live microbe (not necessarily a proven probiotic) and a substrate (not necessarily a proven prebiotic) that the microbe can utilize for its growth. The combination of these components has a synergistic effect in promoting health.

In practical terms, a product labeled as a symbiotic blend typically contains a well-researched and proven probiotic strain combined with a proven prebiotic ingredient. The prebiotic substrate is often a fiber or polyphenol blend, which can selectively support the growth and activity of the probiotic microorganisms in the gut.



The scientific community has proposed various terms for inanimate microorganisms and their components that can provide health benefits. Some commonly used terms for these substances include non-viable probiotics, paraprobiotics, ghostbiotics, heat-inactivated probiotics, and postbiotics.

In 2021, the International Scientific Association for Probiotics and Prebiotics (ISAPP) defined postbiotics as “a preparation of inanimate microorganisms and/or their components that confer a health benefit on the host.” This definition encompasses various substances derived from microorganisms that can positively affect human health.

Postbiotics can include various components such as cell components, cell fragments, and metabolic products of microorganisms. These substances can be derived from microbial sources, including bacteria, yeast, and fungi.

The health benefits of postbiotics are thought to arise from their interactions with the host’s body, including interactions with the immune system, promoting a healthy gut environment, and influencing various physiological processes.

It’s worth noting that the term postbiotics has gained significant recognition within the scientific community. However, it is important to continue researching and understanding the specific mechanisms of action and health benefits associated with these inanimate microorganisms and their components. Next, let’s identify the by-products we want produced by a healthy gut microbiome.

Beneficial gut microbiome byproducts

Intestinal microorganisms play a crucial role in various metabolic processes, including producing short-chain fatty acids (SCFAs). SCFAs, also known as volatile fatty acids, are an essential carbon flow from the diet to the host microbiome. They have several beneficial effects on the host’s health.

Maintaining a balanced intestinal microbiome promotes overall health and prevents diseases. Probiotic microorganisms have been found to positively impact the balance of the intestinal microbiome and the production of metabolites, including SCFAs.

Only a few of the approximately 60 known phyla of bacteria are commonly found in the human intestines. These include Firmicutes, Bacteroides, Actinobacteria, Fusobacteria, Proteobacteria, Verrucomicrobia, Cyanobacteria, and Spirochaetes. However, the two dominant bacterial phyla in the human gut are Gram-positive Firmicutes (such as Lactobacillus spp., Bacillus spp., and Clostridium spp.) and Gram-negative Bacteroidetes.

These phyla contain various bacterial species that contribute to the diversity and functionality of the gut microbiota. Imbalances in the relative abundance of these phyla have been associated with certain health conditions.

The gut microbiome has a remarkable ability to biotransform various chemical compounds. One of its essential roles is converting complex nutrients into simpler forms that the host can easily absorb and utilize.

Intestinal microorganisms break down complex nutrients, including plant cell wall components such as cellulose, pectin, hemicellulose, and lignin. These components are typically indigestible by the host’s enzymes alone. However, the gut microbiota contains specialized microorganisms with the necessary enzymes to degrade these complex carbohydrates. And when the fermentation starts- magic!

Short-chain Fatty Acids

Gut bacteria microbially ferment complex nutrients, producing short-chain fatty acids (SCFAs) as metabolic byproducts. The most common SCFAs produced in the gut are acetate, propionate, and butyrate, which constitute 95%, while formic, valerian, caproic, and lactic acids comprise approximately 5% and play lesser roles.

SCFAs have several vital functions in the body. They serve as an energy source for the cells lining the colon and are also absorbed into the bloodstream, where they can have systemic effects. For example, butyrate is a primary energy source for colonocytes and helps maintain the integrity and health of the intestinal barrier.

SCFAs also have anti-inflammatory properties, help regulate immune responses, and contribute to overall health and proper gut functioning. They have been associated with various health benefits, including promoting gut motility, improving nutrient absorption, and influencing metabolic processes.

SCFA production in commensal(host) and probiotic strains of bacteria

Commensal (host microbiome) species of bacteria noted to produce beneficial SCFA’s:

Bifidobacterium spp., Blautia hydrogentrophica, Prevotella spp., and Streptococcus spp. have been shown to produce acetic acid. Akkermansia muciniphilia and Bacteroides spp. have both been shown to produce acetic and propionic acid. Dalister succinatiphilus, Eubacterium spp. (e.g., E. halli), Megasphaera elsdenii, Phascolarctobacterium succinatutens, Roseburia spp., Salmonella spp., and Veillonella spp. have all been demonstrated to produce propionic acid.

Coprococcus spp. (e.g., Coprococcus catus), Roseburia inulinivorans produce both propionic and butyric acid. Anaerostipes spp., Coprococcus comes, Coprococcus eutactus, Clostridium symbiosum, Eubacterium rectale, Eubacterium hallii, Faecalibacterium spp. (e.g., Faecalibacterium prausnitzii), Roseburia spp. (e.g., Roseburia intestinalis) are major butyrate producers. Finally, we know that Clostridium spp. and Ruminococcus spp. have been shown to produce acetic, propionic, and butyric acid. I’m sure the database will grow daily and be larger once this article is published!

Let’s take a break here to note that you will find a breakdown of good microbiome labs and testing, which will be discussed at length near the end of this article. Get acquainted with some of the heavy-hitter species you want in your microbiome.  Let me say the same with the upcoming discussion of probiotics, which we are only starting to see being produced for clinical outcomes. Here are the top ones.

Bifidobacterium spp. will produce mainly acetic and lactic acids. Lactobacillus rhamnosus GG (LGG) and Lactobacillus gasseri produce primarily propionic and lactic acids.  Bifidobacterium longum and Bifidobacterium bifidum produce acetic, propionic, and lactic acids. Lactobacillus salivarius spp salcinius and Lactobacillus agilis produce propionic, butyric, and lactic acids. Finally, a well-studied strain, Lactobacillus acidophilus, has been demonstrated to produce acetic, propionic, butyric, and lactic acids.

Now, let’s examine the benefits of the main SCFAs. Butyrate leads the pack for overall health, but acetate and propionate are gaining steam as research progresses. To illustrate the importance of SCFAs, let’s start by discussing the “master SCFA”: butyrate.

Butyrate and gut health

Butyrate is often considered a “master” short-chain fatty acid (SCFA) due to its numerous beneficial effects on the gastrointestinal tract and overall health. Specific gut bacteria primarily produce butyrate through the fermentation of dietary fibers, such as resistant starches and other complex carbohydrates.

Butyrate plays a crucial role in maintaining gut health and function. Some key functions and benefits of butyrate include:

  1. Energy Source: Butyrate is the primary energy source for the cells lining the colon, known as colonocytes. These cells rely on butyrate to fuel their metabolic processes and maintain structural integrity.
  2. Gut Barrier Integrity: Butyrate helps to strengthen the gut barrier by promoting the production of mucin, which forms a protective barrier in the intestinal lining. This barrier helps prevent the entry of harmful substances into the bloodstream.
  3. Anti-Inflammatory Effects: Butyrate has anti-inflammatory properties and can help modulate the immune response in the gut. It can reduce inflammation and promote the balance of immune cells in the gut, which is beneficial for conditions characterized by inflammation, such as inflammatory bowel diseases (IBD).
  4. Regulation of Gene Expression: Butyrate can influence gene expression in colon cells, leading to changes in cellular processes related to inflammation, cell proliferation, and apoptosis (cell death). This regulatory function contributes to the maintenance of a healthy gut environment.
  5. Metabolic Benefits: Butyrate has been shown to influence metabolic processes related to glucose and lipid homeostasis. It can help regulate blood sugar levels, improve insulin sensitivity, and help maintain a healthy metabolism.

In conditions where there is an imbalance in the gut microbiome, leading to a decrease in the number of butyrate-producing bacteria and a reduction in SCFA levels, such as in inflammatory bowel diseases (IBD), irritable bowel syndrome (IBS), type 2 diabetes (T2D), obesity, autoimmune disorders, and cancer, the beneficial effects of butyrate may be disrupted.

This imbalance can contribute to gut barrier dysfunction, low-grade inflammation, and metabolic dysregulation in these conditions.

Therefore, promoting butyrate production and maintaining a healthy balance of SCFAs in the gut through dietary interventions, probiotics, and prebiotics can support gut health, reduce inflammation, and improve metabolic outcomes in these conditions.

Butyrate and the gut-brain barrier

The bidirectional communication between the gut microbiome and the central nervous system, known as the gut-brain axis, is an area of growing research interest. Short-chain fatty acids (SCFAs) influence, particularly butyrate, on neural processes, and neuroinflammation, is critical to this interaction.

While systemic absorption of SCFAs from the intestine into the bloodstream is minimal, with butyrate exhibiting lower concentrations than propionate and acetate, it’s important to note that the concentration of SCFAs in the brain itself is negligible. This means that direct activation of neuronal receptors by SCFAs in the brain is unlikely.

Instead, the proposed mechanism for SCFAs’ influence on neural processes is through the regulation of neuroinflammation. SCFAs, particularly butyrate, have been shown to have anti-inflammatory effects on the gut and systemic circulation.

These anti-inflammatory properties can indirectly impact the brain by modulating immune responses and reducing inflammation.

Neuroinflammation, characterized by activating immune cells and releasing pro-inflammatory molecules in the brain, has been implicated in various neurological disorders and conditions. By regulating neuroinflammation, SCFAs can influence neuronal function, mood, memory, and recovery after injuries.

Moreover, SCFAs can indirectly affect the gut-brain axis by modulating the release of certain neurotransmitters, such as serotonin and gamma-aminobutyric acid (GABA), which play essential roles in mood and cognition.

The specific mechanisms by which SCFAs modulate neuroinflammation and influence neural processes are still an area of ongoing research. However, the emerging evidence suggests that the gut microbiome and its metabolic byproducts, including SCFAs, have the potential to impact brain function and contribute to the pathophysiology of neurological disorders.

Butyrate and Aging

Gut barrier integrity, enhancement of mitochondrial function, enhancement of immune responses, and even beneficial effects on telomeres all point to butyrate’s role in slowing the aging process. Quickly increase your butyrate levels with the consumption of MCT oil. I use this exclusively for cooking: odorless, tasteless, with a low flash point-perfect!

Propionic acid (Propionate)

The gut microbiome has been implicated in developing and progressing atherosclerotic cardiovascular disease (CVD). Compared to healthy controls, individuals with atherosclerotic CVD have observed changes in gut microbial composition, specifically an increased abundance of certain bacteria and a depletion of butyrate and propionate-producing bacteria.

A metagenome-wide association study found that patients with atherosclerotic CVD had higher levels of Enterobacteriaceae and Streptococcus spp. while experiencing a relative depletion of bacteria that produce butyrate and propionate. This suggests that short-chain fatty acids (SCFAs), including butyrate and propionate, may be functional in promoting cardiovascular health.

Propionate has been shown to have vasodilating effects in the vasculature by activating the G protein-coupled receptor 41 (GPR41) in the vascular endothelium. This activation decreases blood pressure.

Consume omega-3-rich fish like sardines, salmon, or mackerel to increase propionate levels. Omega-3 fatty acids, found in abundance in these types of fish, have been associated with beneficial effects on cardiovascular health. Due to propionate levels? At least partially, yes, indeed. Now, let’s turn to our last SCFA, acetate.



Acetate, one of the short-chain fatty acids (SCFAs), plays a role in weight control and metabolic issues, particularly insulin sensitivity. The interplay between the gut microbiota, host metabolism, and metabolic health is an area of growing research interest.

The gut microbiota has been found to regulate various aspects of metabolism and peripheral tissues such as adipose tissue, skeletal muscle, liver, and pancreas through the production of metabolites, including SCFAs. Acetate has been shown to benefit host energy and substrate metabolism.

Animal and human studies have demonstrated that acetate influences metabolism by promoting the secretion of gut hormones such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY).

These hormones affect appetite regulation, leading to a reduction in food intake. Additionally, acetate has been found to reduce whole-body lipolysis, lower systemic levels of pro-inflammatory cytokines, increase energy expenditure, and enhance fat oxidation.

These effects of acetate on host metabolism contribute to improved insulin sensitivity and may have implications for weight control and metabolic health. Because of the recent social media attention regarding vinegar ingestion and the national obsession with weight loss, let me discuss how to increase your acetate levels.

Acetate from Dietary Sources

Because recommending a TBSP of vinegar daily has become so commonplace, I will spend some time discussing why this might be beneficial. It’s not for the reasons touted in “folklore.” Commonly consumed kinds of vinegar contain between 4% and 8% acetic acid, and vinegar ingestion has gained attention in the scientific literature because of its acute effects on glucose and lipid metabolism.

Oral ingestion of vinegar can rapidly increase circulating acetate levels. In healthy participants, serum acetate levels increased from 120 µmol/L during placebo conditions to 350 µmol/L (after 15 min) and 200 µmol/L (after 30 min) following intake of vinegar (100 mL containing 0.75 g acetic acid) and acetic acid capsules (containing 0.75 g of acetic acid), respectively.

Acetic acid, a bioactive component with a dominant flavor in different types of vinegar (including cider, malt, plum, sherry, tomato, and wine vinegar), increases circulating acetate levels. It is important to consider the type of vinegar used, as its phenolic, flavonoid, and acetic acid content composition may differ.

Some kinds of vinegar, such as apple cider vinegar, grape vinegar, sherry vinegar, and balsamic vinegar, may contain other polyphenol residual components like gallic acid and catechins. These compounds have been linked to various health benefits, including improved blood sugar control, reduced inflammation, and reduced risk of chronic diseases.

In terms of microbiome alterations that produce more acetate-producing species, human fasting and caloric restriction interventions have described an increase in microbial diversity and abundance of essential acetate producers, such as Akkermansia muciniphila (A. muciniphila) and Bifidobacteria. Now, let’s switch gears back to the gut microbiome and what exactly shapes its composition. We’ll start with the basics.

What Shapes the Adult Microbiome?

Diet: Indeed, short—and long-term dietary habits significantly impact the gut microbiome. Short-term changes in diet can lead to rapid but reversible shifts in the microbiome, often accompanied by intermittent gastrointestinal symptoms.

Fiber, particularly microbiota-accessible carbohydrates (MACs), is crucial in nurturing the gut microbiome. When gut microbes ferment MACs, they produce short-chain fatty acids (SCFAs), such as acetate, butyrate, and propionate. These SCFAs have numerous health benefits, including improving gastrointestinal transit by influencing serotonergic pathways.

Low-MAC diets, which are low in fiber, can cause negative shifts in the gut microbiome. The lack of MACs essentially starves the gut microbes, leading them to seek food sources from the host epithelium and mucus. This epithelial barrier disruption can increase the risk of gut inflammation and other gastrointestinal issues.

In addition to low-fiber diets, additives like emulsifiers and artificial sweeteners can adversely affect the gut microbiome and increase the risk of metabolic and inflammatory disorders.

Optimizing fiber and MAC intake is recommended to promote a healthy gut microbiome and overall health. Including fiber-rich foods like fruits, vegetables, whole grains, legumes, and nuts can support the growth and diversity of beneficial gut bacteria. Minimizing the consumption of processed and packaged foods that contain additives can also help maintain a healthy gut microbiome.

Stress: It is well known that stress can negatively impact immune function. When your body perceives stress, it diverts energy and resources from the immune system to prioritize immediate survival responses. This shift in energy allocation can make you more susceptible to infections and result in more severe symptoms. Furthermore, chronic stress can lead to higher levels of inflammation, which can contribute to various health issues.

During stress, immune compounds called cytokines can contribute to the inflammatory response that damages healthy cells. This chronic inflammation can disrupt normal bodily functions and increase the risk of chronic diseases.

Exercise is a natural stress reliever and has numerous benefits for immune function. Physical activity can help lower inflammation, balance hormones, and strengthen the immune system. Exercise can increase the production of antibodies and stimulate the release of endorphins, which are natural mood elevators. These positive effects of exercise can help reduce stress and its impact on the immune system. Let’s delve into that a bit more.

Exercise: Exercise has been shown to positively impact the gut microbiome by increasing the abundance of beneficial bacteria and promoting gut diversity. Studies have found that athletes tend to have a more diverse gut microbiome and lower levels of inflammatory markers. Animal studies have also demonstrated that exercise-related changes in the gut microbiome can reduce susceptibility to inflammation and weight gain.

It’s important to note that the changes in the gut microbiota induced by exercise can be similar in magnitude to, but different from, dietary changes. While exercise can contribute to weight management, sustained weight loss also requires nutritional changes. Both training and a healthy diet are complementary in improving overall health, including the gut microbiome.

To achieve significant changes in the gut microbiota through exercise, it is generally recommended to engage in moderate to high-intensity exercise for 30 to 90 minutes at least three times per week or accumulate between 150 and 270 minutes weekly for a minimum of eight weeks. This consistent exercise routine will likely produce noticeable changes in the gut microbiome.

Vagal nerve stimulation: The brain, gut, and microbiota are connected through a bidirectional communication pathway known as the microbiota-gut-brain axis. This communication involves the autonomic nervous system, particularly the vagus nerve (V.N.). The Vagus nerve is a mixed nerve composed of approximately 80% afferent fibers (transmitting information from organs to the brain) and 20% efferent fibers (transmitting information from the brain to organs).

The Vagus nerve plays a crucial role in interoceptive awareness, allowing it to sense microbiota metabolites through its afferent fibers and transfer this information to the central nervous system. This information is then integrated into the autonomic network, influencing various physiological processes.

One important pathway mediated by the Vagus nerve is the cholinergic anti-inflammatory pathway. Through this pathway, vagal fibers release anti-inflammatory neurotransmitters, dampening peripheral inflammation and reducing intestinal permeability. By modulating inflammation and gut permeability, this pathway may play a role in shaping the composition of the gut microbiota and promoting healing of the gastrointestinal tract, including the “leaky gut” phenomenon.

Conversely, stress, accompanied by the release of cortisol, can inhibit the function of the Vagus nerve. This can negatively impact the gastrointestinal tract and the gut microbiota.

Chronic stress is implicated in the pathophysiology of conditions such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), which are characterized by dysbiosis (microbial imbalance) and increased gut permeability. Vagal nerve stimulation with a device like the one found here has been demonstrated to improve gut permeability and microbial balance.

Sleep: Lack of sleep and poor sleep quality can significantly impact the quality of the gut microbiome. Research has shown that even two days of sleep deprivation can cause a noticeable shift in the ratio of Firmicutes to Bacteroides, two major bacterial phyla in the gut. This shift may have implications for metabolic health and weight regulation.

Sleep disturbances can also lead to changes in the composition of the gut microbiota, favoring less metabolically friendly species. Studies in mice have shown that chronic sleep fragmentation can decrease the abundance of beneficial Lactobacillus species in the gut, which have various health-promoting effects.

Ongoing research illuminates the importance of adequate and restful sleep for maintaining a healthy gut microbiome. Sleep is a critical restorative process for the body, and disruptions can have wide-ranging effects on various physiological systems, including the gut microbiota.

Medications: PPIs, antibiotics, laxatives, statin drugs, metformin, statins, benzodiazepines, hormones, antidepressants, antihistamines, and nonsteroidal anti-inflammatory drugs are examples of all the medications that are associated with changes in the composition of the gut microbiota. Never has it been more apparent that the fewer pharmaceuticals we ingest, the better!

Smoking: Studies show that smokers have lower levels of acetic, propionic, and butyric acid and decreased levels of beneficial Bifidobacterium. Overall, smokers show less microbiome diversity.

Pollution: Data is emerging showing that pollution negatively impacts the gut microbiome. Some studies correlate pollution exposure to increased levels of inflammation associated with decreased butyrate production.

We are learning more and more about the effects of “forever chemicals” on the immune system and, in parallel, on the microbiome. It’s not good. Specific data links the ubiquitous forever chemical PCB to a notable decrease in microbiome diversity.

Geography, urban versus rural living unrelated to pollution per se reveal quite a range of different microbiome compositions, and this data continues to emerge. Undoubtedly, we’ll see data linking the excellent health in the “blue zones” to more diverse and healthy microbiomes.

Shout-out to older siblings and furry pets: Children with older siblings and (moreso) the owners of furry pets have more diverse and generally healthier microbiomes. This bolsters my theory that every child needs a pet!

Now that we know what can disturb the microbiome let’s discuss the best diet to support our microbiomes.

Healthiest Microbiome Diet

Diet plays a crucial role in establishing gut health and supporting the growth of beneficial bacteria in the microbiome. Over the years, research has shown a strong connection between a person’s microbiota, digestion, body weight, and metabolism.

Studies have revealed that the microbiome environments can differ significantly depending on the diet of humans and other mammalian species. Different dietary patterns can lead to variations in the composition and diversity of the gut microbiota.

Conversely, the health of your gut can also affect how your body processes nutrients from your diet and stores fat. The gut microbiota has been found to play a significant role in obesity, and changes in the bacterial strains present in the gut can lead to notable changes in health and body weight in just a few days.

For example, experiments with mice have shown that germ-free mice, which lack any gut microbiota, become fatter when they receive a transplant of gut microbiota from conventional or fat mice, even without any increase in food intake. This suggests that the gut bacteria can influence hormone production, such as insulin, and affect nutrient extraction and fat storage.

These findings highlight the intricate relationship between gut microbiota, diet, and metabolic health. It is becoming increasingly clear that maintaining a balanced and healthy gut microbiome through a nutritious diet is crucial for optimizing digestion, body weight management, and overall metabolic well-being.

Now that you can see why it’s critical to lower inflammation and support gut health let’s examine how to do this.

Foods that promote inflammation= avoid

 The items listed below are commonly associated with adverse effects on gut health and overall well-being. Let’s go over each of them.

  1. Pasteurized dairy products: These can be common allergens for some individuals. Dairy products also contain lactose, a sugar that can be difficult to digest for people with lactose intolerance. Additionally, specific pasteurization processes may reduce the presence of beneficial bacteria in the dairy products.
  2. Trans fats/hydrogenated fats: Trans fats, commonly found in processed and fried foods, can harm gut health. They can disrupt the integrity of the gut lining, promote inflammation, and negatively impact the gut microbiota.
  3. Added sugars: Excessive added sugars, often found in processed foods and beverages, have been linked to adverse effects on gut health. High sugar intake can disrupt the balance of the gut microbiota and contribute to inflammation and various health issues.
  4. Refined carbohydrates and processed grain products: Foods like refined grains, white bread, and processed cereals are often low in fiber and nutrients and can lead to dysbiosis (imbalanced gut microbiota). These foods can also cause rapid spikes in blood sugar levels, negatively impacting gut and overall metabolic health.
  5. Refined vegetable oils: Refined vegetable oils, such as canola, corn, and soybean, are often high in pro-inflammatory omega-6 fatty acids. Imbalanced ratios of omega-6 to omega-3 fatty acids can contribute to systemic inflammation, including in the gut.
  6. Conventional meat, poultry, and eggs: Conventionally raised meat, poultry, and eggs can contain higher levels of omega-6 fatty acids due to the animals’ diets mainly consisting of corn and cheap feed. This can disrupt the body’s balance of omega-3 to omega-6 fatty acids, leading to inflammation and imbalances in the gut microbiota.

To support gut health, it is recommended that people focus on a diet rich in whole, unprocessed foods—including many fruits, vegetables, whole grains, legumes, and lean protein sources. Choosing healthy fats, such as avocados, nuts, seeds, and olive oil, is also beneficial.

Additionally, incorporating fermented foods like yogurt, sauerkraut, and kimchi can provide beneficial bacteria for the gut. Let’s take these general recommendations and spell them out more useably so that you know what you can and should eat.

Anti-inflammatory foods

  1. Fresh vegetables: These are packed with beneficial phytonutrients linked to various health benefits, including reduced cholesterol, triglycerides, and symptoms of multiple diseases. Aim for different vegetables and try to have at least four to five servings daily. Some highly nutritious options include beets, carrots, cruciferous vegetables (broccoli, cabbage, cauliflower, kale), dark leafy greens (collard greens, kale, spinach), onions, peas, salad greens, sea vegetables, and squashes.
  2. Wild-caught fish, cage-free eggs, and grass-fed/pasture-raised meat: These options are higher in omega-3 fatty acids and provide essential nutrients like zinc, selenium, and B vitamins. When including fish, eggs, or meat in your diet, opt for these healthier choices.
  3. Herbs, spices, and teas: Herbs and spices like turmeric, ginger, basil, oregano, and thyme have potent antioxidant and anti-inflammatory properties. Green tea and organic coffee in moderation can also be beneficial.
  4. Whole pieces of fruit: Eating whole fruits instead of fruit juice is essential to get the maximum benefits of the fruits’ nutrients, including antioxidants like resveratrol and flavonoids. Incorporate three to four servings of fruits per day. Some excellent choices include apples, blackberries, blueberries, cherries, nectarines, oranges, pears, pink grapefruit, plums, pomegranates, red grapefruit, or strawberries.
  5. Healthy fats: Grass-fed butter, coconut oil, extra virgin olive oil, nuts, and seeds are all excellent sources of healthy fats that can support gut health and well-being.
  6. Probiotics: Probiotic foods contain beneficial bacteria that populate the gut and help fight off harmful strains. Including probiotic foods like yogurt, kombucha, kvass, kefir, or cultured veggies in your daily diet can promote a healthy gut microbiota.
  7. Ancient grains and legumes/beans: Sprouted and unrefined/whole ancient grains and legumes/beans are a good source of fiber, nutrients, and plant-based protein. Including two to three servings per day or less is recommended. Examples include Anasazi beans, adzuki beans, black beans, black-eyed peas, chickpeas, lentils, black rice, amaranth, buckwheat, and quinoa.

Treats: Red wine and dark chocolate/cocoa in moderation contain prebiotics! These can be consumed several times per week or a small amount daily. Now, what about supplements?

Best gut microbiome supplements

When discussing supplements for the microbiome, we generally talk about prebiotic supplements. I mentioned a few in the discussions above, but here are the main ones used today. Here are some common flavonoid prebiotic supplements that are frequently “multi-use.”

We often use catechins, including EGCG supplements derived from green tea, which have been shown to be anti-cancer in several studies. We also use quercetin and fisetin, both of which are multi-use supplements.

Continuing in the flavonoid class are the curcuminoid polyphenols curcumin and turmeric. Rounding out this class of supplements are stilbenes: resveratrol and pterostilbene.

In the category of resistant starch, potato flakes have gained popularity lately.

Probiotics are next when it comes to supplementation, with species identified to reinforce the gut lining (Akkermansia M.), improve gut microbiome diversity (sporulating species; mostly Bacillus), as well as Lactobacillus and Bifidobacterium species, which help metabolism and mood, and much more. As an example, pouring through PubMed looking for probiotics to help reduce anxiety by increasing GABA yields the following information.

Some probiotic strains that can increase GABA (gamma-aminobutyric acid) include Lactobacillus brevis, Bifidobacterium dentium, Bifidobacterium adolescentis, and Bifidobacterium infantis. These strains are part of the lactic acid bacteria (LAB) and bifidobacteria groups, which have been shown to produce GABA. Additionally, other Bacteroides species have been found to produce large quantities of GABA.

As a reminder, there are many ways to improve SCFA production, from consuming a TBSP of vinegar daily for higher acetate levels to taking fish oil supplements to increase propionate levels and using MCT oil for cooking to increase butyrate levels.

The advent of synbiotics and parabiotics has not developed to the point where I can recommend anything specific regarding these two categories. However, no matter what you plan to do to improve your gut microbiome, isn’t it a good idea to know its composition and whether you have enough diversity and SCFA production?

After reviewing all microbiome tests on the market, I have found only one test with enough data and recommendations to be considered accurate and “actionable.” It’s this one. If you haven’t received it yet, get it on the app and let me explain next.


Best microbiome test=microbiome labs (Yes, there’s an app for it!)

Most microbiome tests out there are, frankly, useless. The Injoy test is different – it integrates microbiome data with dietary, lifestyle, and symptomatic information through Patient-Reported Outcomes (PROs), painting a complete picture of gut health.

1 – In-Depth Longitudinal Analysis:

  • They require three samples, not just a one-off snapshot (which invites uncertainty). This approach allows us to track changes over time, providing diagnostic-grade data even in a wellness test. They have published and patented this.
  • Their database isn’t just extensive (35K+ samples); it’s specifically focused on people with validated GI issues (IBD/IBS). Meaning you are comparing yourself with a relevant dataset.

2 – Cutting-Edge AI, Gutchat:

  • The app’s health check-ins are based on validated questionnaires used in clinical practice, ensuring their relevance.
  • They’ve sifted through 50K+ scientific papers, distilled them, and ensured they’re clinically sound. This allows users to ask their GutChat any gut health question and receive personalized responses from a credible source.

3 – Actionable Recommendations:

  • Because they capture more than just the microbiome, the reports can be shared with healthcare providers in a way no other report currently can. This enables patients to take action and practitioners to develop more personalized treatment plans.
  • Injoy’s recommendations are accompanied by a ‘confidence score,’ indicating the level of evidence from publicly available research articles that support each recommendation.

Bottom line: We all know the field of microbiome testing is full of overhyped promises. Injoy is not about that. They provide tools that work based on solid science. You can find the Injoy app in your Apple or Google app store. Please use my discount code: DRKIM10. You’re welcome!


Hopefully, you have read this article with more knowledge of testing, evaluating, and improving your gut microbiome. You have learned the terminology of the available products to improve your gut health. You have learned what foods help and what foods “hurt.”

Importantly, you have learned what activities and products to utilize and which ones to avoid. If you feel overwhelmed, start cleaning up your diet from ultra-processed foods and getting an Injoy kit. At some point in the not-too-distant future, good medical practices will be based not just on patient history, physical exams, and bloodwork but also on the results of microbiome testing. As an important addendum, there are studies linking various herbal supplements with the production of SCFA in the gut, but rather than give you a huge laundry list, I feel that you will benefit from getting an Injoy kit and then supplementing scientifically with the help of their AI-powered GutChat.



Part 1: The toxins known as forever chemicals

In this article, we will examine the effects of the forever chemicals that cause immunotoxicity and consider immune system boosters that help deal with the fallout. These immune system boosters can protect against a wide range of health problems, but our focus in this article will be on protection from forever chemicals. First, let’s clarify what immunotoxicity actually is.

What Exactly is Immunotoxicity?

Immunotoxicity occurs when a toxic substance alters your immune system, either suppressing it or triggering an exaggerated response. Certain chemical compounds can sneak into your body and disrupt the way that your immune system is able to communicate and function.

As a reminder, before we get into the discussion of forever chemicals: be aware that many things are immunotoxic. Overly processed foods, heavy metals, chronic infections, and chronic inflammatory conditions are immunotoxic. This then causes detox organs to be overloaded, cognitive issues, hormonal problems, depression, and all sorts of other health problems that I’ll review and discuss in the second half of this article, where we focus on immune system boosting.

Common Immunotoxic “additives”

  • Pesticides, herbicides, and fertilizers: These chemicals, and yes, some are indeed forever chemicals, are sprayed on many agricultural crops. Buying “organic only” goes a long way.
  • Heavy metals: An accumulation of metals like lead, mercury, and nickel are just a few environmental toxins that can suppress your immune system.
  • Pharmaceuticals: Medications like “steroids” (e.g., prednisone or Medrol), and all “biologics” are toxic to our immune systems.
  • Cigarette smoke: Cigarette smoke – including secondhand smoke – contains a startling number of toxic chemicals.
  • Benzene: This carcinogenic industrial chemical is frequently used in paint, detergents, dyes, and glues.
  • Beauty and personal care products: Many conventional beauty and personal care products contain a long list of toxic chemicals. These chemicals can be absorbed through your skin and delivered directly into your bloodstream. I’ll get into how to choose wisely later on in this article.
  • Indoor air pollution: When we seal up our windows and doors, polluted outdoor air can get trapped inside. But indoor pollution is compounded by pollutants that come from cleaning products, air fresheners, carpeting, furniture, and even paint on walls in the form of VOC’s.

Luckily, I have “just the thing” for you, along with a $500 discount. This amazing indoor air purifier takes care of VOCs from the products just mentioned and also kills viruses (COVID!), bacteria, and mold. Here’s where to get information and a huge discount on the Space Station’s air purification system technology (tailored to your home), not yet on the market.

  • Contaminated water: Water is a great solvent, and it circulates throughout our world, potentially exposing us to a plethora of pollutants ranging from heavy metals to pharmaceuticals.
  • Outdoor air pollution: Outdoor air pollution can come from natural sources like wildfires or dust storms as well as man-made sources like emissions from vehicles, chemical plant off-gassing, and industrial manufacturing processes.
  • Toxin-laden food: Not only are many of the foods we eat drenched in toxic chemicals like pesticides and herbicides, but modern processing and packaging methods can introduce even more chemicals into our food supply.

Although several industrial chemicals and toxins have been identified as carcinogens and subsequently regulated, many more persist in the environment and continue to be used freely. The following are the biggest offenders and will be discussed in this order:

  • BPA
  • Phthalates
  • Pesticides
  • Dioxins and Polychlorinated Biphenyls (PCBs)
  • Per- and Polyfluoroalkyl Substances (PFAS)
  • Microplastics

Bisphenol A (BPA)

Bisphenol A, or BPA, is an additive used to make clear and hard polycarbonate plastics, as well as epoxy and thermal papers. BPA is one of the highest-volume chemicals produced each year, with roughly 6 billion pounds produced annually. It is traditionally found in many clear plastic bottles as well as in the lining of canned foods.

The estrogenic properties of bisphenol-A (BPA) have been associated with cardiovascular disease, obesity, and male sexual dysfunction. Since 2012, BPA has been banned in sippy cups and baby bottles, but there is some debate as to whether its replacements–bisphenol S (BPS) and bisphenol F (BPF)–are any safer; they appear to have similar hormonal effects as BPA.

BPS and BPF are analogs of BPA, not a solution to solve the harmful effects of BPA. The analogs can be found in daily-use products and are used in several industrial applications but are being phased out. Several well-done studies prove that BPA has a high carcinogenic potential, with known mechanisms to trigger breast, ovarian, prostate, cervical, and lung cancers. Therefore, it is clear that its analogs are also xenoestrogens since they can exert similar effects to BPA and cannot be considered viable alternatives for its replacement.

As with phthalates (coming up next), the majority of BPA ingestion is thought to be food-related. A large clinical study finds that 93% of American urine samples contain BPA.

To reduce your exposure, I recommend that you follow some easy steps. Buy only BPA-free canned food. Minimize your contact with so-called thermal papers such as receipts and tickets, or simply use hand sanitizer after handling.

Try to avoid polycarbonate plastics (identifiable with the recycling code number 7). Store leftovers in glass or stainless steel containers. If plastic must be used, opt for polycarbonate- and polyvinyl chloride–free plastics. Never reheat food (including the microwave) in plastic containers or wrapping.


Phthalates are chemicals used to make plastics soft and durable, as well as to bind fragrances. They are found in many common household items such as vinyl flooring and shower curtains; air fresheners, perfumes, candles, and other products that contain scents; and many personal care products such as moisturizers, nail polishes, and removers, hair sprays, and dry shampoo.

Phthalates are chemicals known to disrupt the hormone system, and they have been associated with abnormal sexual development in children as well as lower levels of testosterone in men. It is thought that most human exposures occur via inhalation, ingestion, and skin contact; however, fasting studies demonstrate that most exposure comes from food packaging materials.

Avoid polyvinyl chloride plastics (not yet FDA-banned!), which are identifiable by the recycling code number 3, as well as air fresheners and fragranced products which are chemically based rather than being scented with essential oils. A good source to check for problems is the Environmental Working Group website.

The EWG’s Skin Deep database is a great resource on phthalate-free personal care products and much more, so do check them out.


The United States uses an estimated 1 billion pounds of pesticides each year, including nearly 300 million pounds of glyphosate. The European Union has identified this chemical as a probable carcinogen, although the U.S. Environmental Protection Agency (EPA) has not yet reached this conclusion. The matter is currently being litigated, despite the fact that the makers of Round-up are repeatedly paying out lawsuits for cancers related to this environmental poison.

It has been found that over 90% of the US population have pesticides in their urine and blood, regardless of where they live. The exposures are (obviously) thought to be food-related.

A large European prospective cohort study found that people who ate organic foods had a lower risk for cancer. In addition, tests on the blood of members of this same group showed that relatively elevated levels of a pesticide known as beta-hexachlorocyclohexane (B-HCH) are associated with higher all-cause mortality.

In addition, exposure to DDE – a metabolite of DDT, a pesticide heavily used in the 1940s-1960s that still persists in the environment today – has been shown to increase the risk for Alzheimer ‘s-type dementia as well as overall cognitive decline.

Because chlorinated pesticides are often fat-soluble, they accumulate in animal products. Therefore, people consuming a vegetarian diet have been found to have lower levels of B-HCH than meat eaters. According to studies, consumers of produce should favor organic over conventional if possible. The EWG provides wonderful consumer resources to check for pesticides in produce.

Dioxins and Polychlorinated Biphenyls (PCBs)

Dioxins are byproducts of industrial practices and result from incineration, trash burning, and fires. PCBs (polychlorinated biphenyls), which are structurally related to dioxins, were previously found in products such as flame retardants and coolants. Dioxins and PCBs are often grouped under the umbrella term “persistent organic pollutants” because they break down slowly and remain in the environment even after emissions have been curbed.

The best-known dioxin, tetrachlorodibenzodioxin, is a known carcinogen. Dioxins have also been associated with a host of health implications in development, immunity, and reproductive systems. PCB exposure has also been linked to an increased risk of mortality from cardiovascular disease.

PCBs can also induce dysbiosis of the gut and dysregulate physiology of the gut and brain. Extensive research has been conducted on the importance of the microbiome in the developing brain and its possible links with autism spectrum disorder (ASD) and Alzheimer’s disease.

Since the 1980s, dioxin emissions have been reduced by 90 percent, and since 1979, the US Environmental Protection Agency (EPA) has banned the use of PCBs in industrial manufacturing. However, environmental dioxins and PCBs still enter the food chain and accumulate in fat.

The levels of dioxins and PCBs found in eggs, meat, dairy, and fish are approximately 5-10 times higher than they are in plant-based foods.

Therefore, you can easily limit your exposure by reducing your consumption of animal products, as well as being sure to remove the skin and fat from meats. Research has shown that farmed salmon is one of the most PCB-contaminated protein sources in the U.S. diet! We also know that farmed fish are sprayed with pesticides to kill lice. (Yuk!) So—obviously, my advice to you regarding fish is to eat “wild-caught.”

Per- and Polyfluoroalkyl Substances (PFAS)

PFAS is an acronym for perfluoroalkyl substances, a group of fluorinated compounds discovered in the 1930s. Their chemical composition includes a durable carbon-fluorine bond, giving them a persistence within the environment that has led to their being referred to as “the most forever” of “forever chemicals.”

Perfluorooctanoic acid (PFOA) was used by 3M to make Scotchgard for carpets and fabrics and by Dupont to make Teflon for nonstick pots and pans. Although PFOA was removed from nonstick cookware in 2013, PFAS — a family of thousands of synthetic compounds — remains common in fast-food packaging, water- and stain-repellent clothing, firefighting foam, and personal care products.

PFAS have been detected in the blood of 98% of Americans and in the rainwater of locations as far away as Antarctica! Even low levels of exposure are associated with an increased risk of cancer, hormonal disruptions, and liver disease. Since this is such a forever chemical that not only seems, but is ubiquitous, I’d like to review for you-the main sources for this toxic group of chemicals.


Cosmetics and personal care products such as dental floss may contain PFAS even if they do not list them on their labels.

Researchers have found that personal care products such as cosmetics contain perfluoroalkyl substances (PFAS). A recent peer-reviewed study of 231 makeup and personal care samples, including lipstick, eyeliner, mascara and foundation, found that more than half of them contained organic fluorine–an indicator of PFAS. It’s also been found in some types of dental floss designed to glide more easily between teeth.

Some makeup manufacturers add PFAS intentionally to make cosmetics last longer and spread easily. In other cases, PFAS is introduced into cosmetics through cross-contamination, such as machinery used in manufacturing or plastic packaging that contains PFAS. A recent lawsuit alleges that cosmetics maker CoverGirl was selling products labeled as “sustainable” despite the presence of PFAS in them.


It’s not the food, it’s the packaging. Food packaging, such as takeout containers and wrappers, pizza boxes, french fry containers, hamburger wrappers, and microwave popcorn bags can all be sources of PFAS contamination in food.

Although some compostable bowls are marketed as being safe for use with hot foods, they may still contain PFAS. The Food and Drug Administration has not restricted the use of PFAS in food packaging; instead it has left it up to states and the public to protect consumers from exposure to these chemicals.

Drinking water

According to an Environmental Working Group report, up to 200 million Americans may be exposed to PFAS in their drinking water. The EPA announced in March 2021 that they will regulate PFAS in drinking water, but the regulations have not yet been finalized. Currently, it is up to individual states to test for its presence in the water. The EWG has compiled a map of all known PFAS contamination sites.

However, it is important to note that PFAS contamination in the water supply is widespread. According to research conducted by the Environmental Working Group, contamination from PFAS has been found in drinking water systems across all 50 states and two U.S. territories, Guam and Puerto Rico.

Bottled water constitutes another emerging risk of PFAS contamination. In 2021, Johns Hopkins researchers found 39 out of 100 bottled waters tested contained PFAS. The Food and Drug Administration has not set PFAS limits for bottled water; however, it is currently considering regulatory action.

Home goods including clothing

New research suggests that people may absorb PFAS through their skin from stain-resistant carpeting, water-repellent textiles and other products. Environmental testing has found indicators of PFAS in everything from athletic clothing to period underwear to stain-resistant clothing.

Firefighting foams

Firefighting foams used on military bases, airports, and forest fires are a big source of PFAS contamination, as this all makes its way to our aquifers.

Wastewater and landfills

Waste from landfills washes PFAS into waterways and soil.

When products such as carpet, clothing, bedding, and food packaging are discarded in landfills, they can release perfluoroalkyl substances (PFAS) into the environment. Rainwater moves these chemicals into nearby rivers and lakes where they create a toxic waste that infiltrates soil and groundwater sources. Typical landfill waste treatment systems do not remove PFAS. Bottom of Form

What can you do to avoid PFAS?

The majority of U.S. states are considering more than 200 bills that would ban or restrict PFAS, including in clothing, personal care products, and food packaging. The U.S. House and Senate are working on their own bills, as well. Until then, you need to protect yourself.

Europe is moving much faster, as they seem to always do when it comes to environmental and consumer protections. The European Union is considering a ban on thousands of PFAS chemicals, other than “essential uses.” A final agreement should come by 2025.

Recall that non-stick cookware is another way that PFAS enters both our food and air. Non-stick cookware still contains alternatives that may be harmful to our health. Labels claiming PFOA-free don’t necessarily mean that the cookware is safe. Look for a PFAS-free label as your safest choice. Instead, use stainless steel, cast iron, glass, or ceramic cookware instead of non-stick pots and pans.

Here are other important ways to limit your PFAS exposure.

  • Limit the use of clothing and other products advertised as “waterproof,” “water-resistant,” or “stain-resistant,” as well as anti-fog eyeglass wipes and sprays.
  • It bears repeating: Cook with stainless steel, glass, cast iron, or ceramic cookware instead of non-stick options.
  • Buy BPI-certified compostable packaging, and ask restaurant servers about the containers they use.
  • Avoid food packaged in greaseproof bags or containers. Instead, use your own glass containers for takeout and leftovers. Encourage restaurant owners to offer takeout packaging made from materials that do not leach PFAS into food. Avoid microwave popcorn from PFAS-treated bags. Pop your corn the old-fashioned way- it’s healthier and tastier!
  • Read personal care product labeling carefully and avoid those with “polyfluor-,” “PTFE,” “perfluor-,” or Teflon on the label.
  • Avoid water and stain-repellent carpeting, upholstery, curtains, tablecloths, napkins and other household textiles.
  • In the wake of recent findings about the health risks associated with PFAS, learn if your water source has been tested for these chemicals. If it contains PFAS or hasn’t been tested, a water filter is a good purchase. However, be aware that not all filters are equally effective; a 2020 Duke University study found that reverse osmosis filters and two-stage filters performed best at eliminating PFAS.
  • If you drink bottled water, purchase water labeled “purified” rather than spring water.


“Microplastics” is an informal term used to describe small pieces of plastic that have broken down or microbeads from household or personal care products, measuring less than 5 mm in length

Plastic waste is accumulating at an alarming rate. By 2050, it is estimated that there will be more plastic than fish in the oceans. (I know!) This could lead to hundreds of thousands of tons of microplastics and trillions of these particles in the seas. A recent study demonstrated that microplastics were present in the bloodstream in the majority of 22 otherwise healthy participants.

Since the 1950s, studies have shown that exposure to plastics can promote tumorigenesis in animal models, and in vitro experiments have demonstrated that microplastics are toxic at the cellular level. However, it’s not clear whether the plastic itself is toxic or if it simply serves as a carrier for other environmental toxins that accumulate in the body.

Microplastics have been widely detected in fish and in fact, just about all seafood, as well as other products like bottled water, beer, honey, and tap water. Although there are no formal advisories on fish consumption to avoid exposure to microplastics at the moment, the Environmental Working Group recommends limiting seafood intake due to concerns over contamination with heavy metals and other pollutants.

Despite mounting pressure for a ban on microbeads in personal care products, the industry has not yet agreed to phase out the production of these synthetic particles. Until such bans are put in place, Here are some things you can do to protect yourself.

  • Avoid single-use plastics
  • Use cloth-based reusable tote bags for grocery shopping rather than plastic bags
  • Use loose-leaf tea or paper tea bags rather than mesh-based alternatives.
  • Check out the EWG website to find personal care products that are microbead-free.

I personally am committed to helping reduce and eventually eliminate plastics from our oceans. You can join me in supporting a great company leading the way called 4Ocean. And now that you have read about all of this pretty nasty stuff, let me help you boost your immune system to counteract your incidental exposures.

Part 2: Immune health and immunotoxicity counter-measures

(Boost Immune System function to counter Immunotoxicity)

To re-cap what these toxins discussed above can do: oxidative stress, inflammation, microbiome disruption, and even “brain damage.” We can use detox products for some of these things, but it’s always best to avoid them where possible. And remember, we don’t have a mechanism to detox from microplastics yet. Therefore, we need to strengthen our immune systems and help with immunotoxicity, viral exposures, and more. Let’s start with the easiest thing to change-your diet. First, I’ll list the topics I’ll cover.

  • Diet
  • Reduction of Inflammation
  • Reduction of oxidative stress
  • Reduction of glycation
  • Sleep
  • Stress management
  • Microbiome health
  • Hot/cold therapy
  • Supplements (links supplied in text below)

Basic Lifestyle Strategies for Immunotoxicity

Diet: I advise all patients to eat an anti-inflammatory diet to help optimize their health.  A simple way to do this is to eliminate highly processed foods, watch your sugar and starchy carb intake, and be careful with gut-damaging lectins found in grains, beans, nightshade vegetables, and low-fat dairy products.

These foods can lead to leaky gut syndrome, which means that your intestinal lining becomes damaged and lets bacteria into your bloodstream. It also leads to disruption and disorder of your microbiome.

Eventually, if you don’t eat an anti-inflammatory diet and instead eat ultra-processed and junk food, you’ll eventually end up with more than immunotoxicity. You’ll end up with systemic inflammation, one of the root causes of all diseases. I’ll get into a more in-depth discussion of inflammation in the next section.

Garlic, horseradish, and wasabi are immune-boosting foods. Garlic is anti-viral and is sometimes used as a supplement; however, this article will not cover its use as such. It’s also essential to eat to support the health of your microbiome.

Microbiome health translates to much better immune system health. I’ll cover this topic in a separate section further on in this discussion.

Vitamin C, vitamin E, and phytochemicals such as carotenoids and polyphenols are dietary constituents with exceptionally high antioxidant and anti-inflammatory capacity. If you don’t consume enough of these compounds, supplement your diet with vitamins or organic vegetable powders like this. Inflammation is the topic to be discussed next.


Acute inflammation is the body’s response to a physical injury. If you have a splinter in your finger and leave it alone, the area will turn red and get puffy. This is because your immune system is rushing to fight off any viruses or bacteria that might have gotten into the injured area. The signs of acute inflammation are heat, redness, swelling, and pain. All of these will dissipate if you allow the body to work through its natural healing process, unencumbered by further injury or infection.

However, if you keep poking yourself in the same spot, the re-injury will keep levels of inflammation elevated and thus, harmful.

That’s exactly what’s happening with chronic internal inflammation, but you can’t  “feel it.”  The inflammatory response is a normal and essential part of the body’s immune system. However, when inflammation becomes chronic, it can cause problems such as lethargy or pain.

As you’ll see, some of the major causes of chronic inflammation include diet, stress levels, and environmental factors like pollution. The following are the major causes of chronic inflammation.

Unhealthy diets:  I know I’ve said this repeatedly, but it’s worth repeating: Eating a healthy diet is not just important; it’s essential to be healthy. Processed sugar and other foods that cause inflammation include sugary foods and beverages, high-processed carbohydrates, high-industrial fat and seed oils, high-gluten foods, and all overly processed and fast foods.

This is the typical U.S. diet, which is why our population is so inflamed! Further, this poor eating pattern also causes oxidative stress, which worsens inflammation. I’ll move on to that next topic when we’re done reviewing inflammation.”

Chronic stress: Life is stressful, indeed. Everything from work to relationships to finances can add up and become too much for us to handle, which can lead to health problems. When this happens, your body has a physiological inflammatory response that includes raising cortisol levels in your blood. Many people eat as a coping mechanism for stress; this is unhealthy because it leads to weight gain; the next topic.

Your weight:  Obesity and being overweight (along with 75% of Americans!) increase inflammation risk. Obese and overweight men and women have higher levels of inflammatory blood markers than men and women of the same age who are not obese or overweight.

Inflammation drops when people lose weight, according to many clinical studies. Luckily, there are now more weight loss tools in our medical kits to make losing weight easier than ever before.

Excessive omega-6 intake: Omega-6 fats form the precursors for inflammatory eicosanoids, which are also an integral part of the inflammatory response. High omega-6 status (especially when combined with poor omega-3 status) means excessive production of inflammatory eicosanoids and a lopsided inflammatory response to normal stimuli. Cut down on your omega-6 intake by reducing your intake of meat and increasing your intake of omega-3 rich seafood.

Insufficient omega-3 intake: Omega-3 fatty acids are precursors for anti-inflammatory eicosanoids, which are integral to the inflammatory process. A poor omega-3 status indicates inadequate production of anti-inflammatory eicosanoids and an unbalanced inflammatory response to normal stimuli. It’s easy to establish good blood levels: eat fish rich in omega-3s such as salmon or sardines, or take supplements containing these essential fatty acids.

Lack of sleep: We know we need it but we don’t do it! Sleep deprivation leads to an increase in blood inflammatory markers. According to the National Sleep Foundation, we either go to bed too late, wake up too early, or use too many electronics late at night-disrupting the sleep quality we get. I’ll go more in-depth into the topic of sleep further on in this article.

Toxins: Heavy metals, biotoxins such as Blue-green algae, Lyme, and mold mycotoxins can cause chronic inflammation. Biotoxins are notorious for causing immunotoxicity. This is why we Functional docs focus on how to boost the immune systems of our CIRS patients.

Lack of movement: Most of us lead far too sedentary lives, which can cause low-grade systemic inflammation. We don’t usually need to walk to get to our destinations; we take escalators and elevators. We sit for hours on end, then don’t make time for regular exercise. If this describes you, make time to move more. Get up on your feet for two to three minutes each hour you’re sitting; better yet, do some push-ups, burpees, or jumping jacks.

Poor recovery and Overtraining: On the other hand, some people move too much, with too little rest and recovery. Overtraining is a form of chronic inflammation. Not just elite athletes, but even casual 10K runners and others who train frequently can overtrain. This degree of over-exertion can cause inflammation, as well as elevated cortisol levels, and disrupted sleep. Now that we’ve gone through some ways not to exercise, let’s discuss how to exercise properly.

Exercise: A large body of research in humans and animals has demonstrated that exercise has a profoundly beneficial impact on immune system function. There is broad agreement that regular, moderate-intensity physical activity (e.g., brisk walking, vacuuming, dancing, doubles tennis, or shooting hoops) for 30 to 45 minutes per day is beneficial for optimal immune function. This correlation has been demonstrated particularly well in older adults and people with chronic diseases.

Exercise is also known to improve intestinal flora composition, so keep this in mind when reading about the microbiome. Some studies have shown that activity is associated with increased microbiome biodiversity and beneficial metabolic functions. Gut microbiota (and all immune functioning) can influence the pathophysiology of distant organs, including skeletal muscle.

The gut-muscle axis regulates muscle protein deposition, muscle function, and insulin sensitivity. This gut-muscle axis may involve maintaining skeletal muscle with aging, which could contribute to improved blood sugar levels and insulin sensitivity.

You may not know that fasting blood sugars, which are not labeled diabetic or even pre-diabetic, will cause cellular glycation, something you might not have heard of. I’ll cover that after we talk about something almost everyone suffers from without knowing it; called oxidative stress.

Oxidative stress

What is it? Oxidative stress occurs when there is an imbalance between the production of free radicals and your body’s ability to counteract their harmful effects through neutralization by antioxidants. Oxidative stress can also occur when you have too many free radicals in relation to your body’s supply of antioxidants. Just as an apple not coated with lemon juice (an antioxidant) turns brown when exposed to air, our cells can “rust” when we have oxidative stress–caused by unopposed free radicals.

Free radicals are unstable molecules that can damage cells or create abnormal ones. Free radicals steal electrons from cell components such as DNA, proteins or lipids to become stabilized. The process destabilizes the cell component molecules and triggers a large chain of free radical reactions.

A proper diet can reverse this unhealthy but common condition. Eat five to twelve servings of organic fruits and vegetables daily or supplement with a high-antioxidant multi-vitamin such as this one. Functional doctors often measure patient’s levels of oxidative stress with a Raman spectroscopy unit, although other methods are available. If you’re aware of this phenomenon, you can prevent it! Here’s what to watch out for and adjust your intake of antioxidants accordingly:

What Causes Free Radicals? Free radicals are a byproduct of energy consumption in our mitochondria, the factories producing energy in each of our cells; especially in the brain, heart, and muscles. When we exercise, our respiratory and heart rates increase, creating more free radicals that need to be quenched by good levels of antioxidants.

However, the free radicals that deplete our antioxidant supply are environmental (for example, cigarette smoke) and result from our lifestyles (for example, eating junk food). Here are the big offenders:

Consuming a “bad” diet: As referenced in the “diet section,” it’s essential to eat as if your health depends on it (because it does!). Eating too many calories, sugars, refined or starchy carbohydrates, processed and fast foods, and lectins do indeed cause oxidative stress and inflammation. Unhealthy foods force our mitochondria to work harder and release more “exhaust,” creating higher levels of free radicals burning toxic foods for energy. Speaking of diet, let’s look at two other popular lifestyle choices.

Eating charcoal-broiled foods: These foods-not just meats-contain polycyclic aromatic hydrocarbons, which contribute to oxidative stress. And yes, char-broiled meats are indeed carcinogenic. Now, let’s move on to some other lifestyle factors in oxidative stress levels.

Excessive alcohol: Alcohol consumption increases your levels of inflammatory cytokines-inflammatory molecules linked to oxidative stress.

Exposure to tobacco smoke: Imagine this-tobacco smoke contains more than 4,000 toxic chemicals that can cause oxidative stress. One cigarette produces millions and millions of free radicals. How’s that for incentive to stop? We who use Raman Spec scanners have reviewed the data, which shows that smokers score in the lowest range, equivalent to those with active cancer cases!

Exposure to air pollutants: Air pollution, industrial pollution, and even airborne allergens increase oxidative stress.

Lack of sleep: Sleep deprivation increases oxidative stress through a complex series of chemical reactions. Yes, I’ll discuss sleep in more depth, too.

Excessive psychological stress: The stress hormone cortisol increases inflammation, which further increases free radical production. It also causes a leaky gut, an asymptomatic cause of chronic inflammation, and the root cause of autoimmune disease.

Exercising too much: Exercise is crucial for optimal health. However, too much of it can increase oxidative stress in our bodies. As a rule of thumb, more than 60 minutes per day is considered excessive. Therefore, all elite athletes need to supplement adequately.

Chronic infections: Hidden (asymptomatic) infections will contribute to oxidative stress. One example is a biofilm-secreting sinus organism called MARCoNS, found in people with mold and mycotoxin illness. Dental infections are another excellent example. If you have root canals, you will not feel apical abscesses-so get a panoramic X-ray annually.

Exposure to fungal toxins: Environmental molds (like those in basements and bathrooms) and internal fungi (such as those colonizing your gut in excess) can produce mycotoxins that increase oxidative stress.

Ionizing radiation and EMFs: Exposure to X-rays, excessive sun, radon, cellphones, hairdryers, airplanes, electric blankets, and heating pads can all contribute to oxidative stress.

Inadequate GI-tract detoxification: I saved this one for last because it is especially Germain to this topic of immunotoxicity due to all of the forever chemicals discussed earlier.

When the liver is overwhelmed by toxins from food (e.g. fructose) or the environment (e.g. forever chemicals), it becomes inflamed and produces more free radicals.

Now that you know what causes this problem, you can combat it by including antioxidant-rich foods, smoothies, and supplements in your diet.

Next, let’s look at the lesser-known phenomenon that is just as harmful to the immune system called “glycation.”


 Cellular glycation (also known as AGEs or advanced glycation end-products) is the stiffening and aging of all cells. It occurs at fasting blood sugar levels somewhere in the range of 75-89 ng/dL. Research continues to lower the bar at which we set the definitions of diabetes, glucose intolerance, and cellular glycation. It is directly related to the amount of body fat an individual carries.

High blood sugar levels are associated with immune system depression, increased risk of dementia and heart disease, cellular aging, and even cancer. Cancer is an immune-mediated disease that is largely preventable through diet and lifestyle modifications.

Studies have shown that certain cancers respond more effectively to treatment when blood sugar levels are lower, which can be achieved through ketosis or medication. Research also suggests that better blood glucose control leads to better sleep. Here’s what you should know about sleep:


Studies show that sleep loss can affect different parts of the immune system, leading to the development of a wide variety of disorders. Sleep deprivation can affect the thymus gland, bone marrow, and lymph nodes, as well as increasing susceptibility to infections and diseases. Here are a few interesting studies to consider before giving you my recommendations for adequate, restful sleep.

Researchers restricted the sleep of study group participants to 4 hours for only one night. The average NK cell activity of those who got 4 hours of sleep was 72% lower than that of those who slept for a full night.

Genetic mutations have been identified in some people who naturally sleep six or fewer hours a day and appear healthy and functional. While it is not yet known how common these mutations are, it may explain why some individuals can get by on less sleep than others.

Many people who say they do not need much sleep are just pushing themselves to sleep less. As a consequence, they then struggle to stay awake and tend to function sub-optimally during the daytime. They are putting themselves at risk for obesity and chronic illness.

What’s your ideal length of sleep? The average sleep times across 5 to 7 relaxed days can be used to determine an individual’s ideal sleeping time. Record the length of time you sleep during a 7-10 day vacation, when you are awakening spontaneously and going to bed only when you are tired.

During this time, limit your caffeine intake to no more than two cups of regular coffee a day (about 200 mg of caffeine). A relaxing vacation can be mimicked by doing an activity to reduce your stress levels at least a couple of times per day. Stress management is not simply about feeling better; it’s also a matter of your health. Now, more about proper stress management.

Stress Management

Stress depresses the immune system in several ways. First, sustained high levels of cortisol–a hormone produced in response to stress–causes gut hyper-permeability (i.e., “leaky gut”), which causes inflammation and subsequent disease. Cortisol also interferes with T-cell production and function, making your body more susceptible to pathogens; this is why you get more head colds when you’re under pressure. Finally, cortisol kills brain cells (neurons), further interrupting the gut-brain axis crucial for proper immune function.

The best way to manage your stress is to incorporate movement and exercise into your day. You can take a walk, dance, or sing for a few minutes every couple of hours. Exercise should be something you will do, not something you’d like to envision yourself doing. Deep breathing, meditation and singing are great habits to cultivate. Some people also benefit from liposomal GABA supplements and peptides with anti-anxiety benefits. The latest findings show that everyone needs more GABA and less cortisol so getting a vagal nerve stimulator to use for 2 minutes twice daily is a must.

I have touched on the importance of gut health, but now I’ll go deeper into that topic by discussing the microbiome:

Microbiome Health 

The human microbiome is a collection of between 10 and 100 trillion genetically unique (mostly) bacterial cells that live in our guts. The health of our gut microbiota influences our immune system, which is also (primarily) located in our guts. Unhealthy gut bacteria thrive on the things that create inflammation in our body, including refined carbs, sugar, unhealthy fats and processed foods. Conversely, the healthy foods and activities discussed previously all contribute to a healthy microbiome. To augment all of these healthy habits, we can add prebiotic fiber and probiotics into the mix. First of all, we need to eat good prebiotic foods as “fertilizers” for probiotics.

Prebiotic fiber 

Prebiotic fiber is non-digestible carbohydrates found in fibrous foods that assist in the growth of healthy bacteria in the gut. White and red onions, as well as asparagus, chicory, garlic, unripe bananas, and Jerusalem artichokes, are great “gut bug food” because they help healthy gut bacteria produce substances such as butyrate. Butyrate protects the lining of the gut and has anti-inflammatory properties in the gut. If you want to ingest more good gut bug food, you can supplement with this. And when your gut garden is ready with its prebiotic fertilizer, you can add back some good gut bugs. Here’s how.

Probiotics: High-quality kefir or yogurt (home-made) and fermented foods such as sauerkraut or kimchi can supply a fair amount of good bacteria, but I generally supplement everyone to ensure they get enough probiotics to augment immune function and combat immunotoxicity. We see some good evidence that sporulating probiotics are more immune-supporting and microbiome-diversity-supporting than the strains of probiotics we used to recommend only recently.

I currently have all patients use a microbiome-augmenting app to help optimize their microbiome with foods, activities, and supplements, including Akkermansia, if they have an insufficient amount in their gut or if they have a gastrointestinal issue.

Immune enhancement with hot and cold therapy

Heat shock proteins (HSP’s) are proteins that form in the body when it is subjected to cold temperatures or high heat, such as when you immerse your body in ice-cold water or a tub or sauna at 104 degrees F. These proteins help strengthen the immune system and aid in various positive immune modulation functions.

Cold therapy can lower cortisol levels when practiced repeatedly. As a reminder, reducing your cortisol level will help preserve the integrity of your gut lining and enhance the 70% portion of your immune system that resides there. In addition, studies show that cold therapy improves anti-tumor white blood cell activity as well as NK (natural killer T cell) activity.

HSP’s, which are induced by saunas (conventional and FIR), trigger positive effects in the immune system regarding infections, autoimmune disease, and even cancer therapy. For this article, suffice it to say that hot and cold treatments are great for your immune system health. Now let’s discuss immune booster supplements.

Supplements to help get rid of Immunotoxicity

(Links are to DFH-to receive my group discount, use my practitioner code:KimCrawford)

Vitamin D

You need vitamin D for an optimally functioning immune system. I actually believe most Americans are aware of this fact due to the COVID crisis.

Vitamin D inhibits harmful immune pathways and promotes beneficial ones, positively impacting the composition of the microbiome and enforcing the gut barrier. Clinical studies show low levels of vitamin D are associated with increased risk of coronavirus infection; previous studies indicate that low levels of vitamin D are linked to more “flu” in general.

Vitamin D dosing: You need a level of 75-80 ng/dL, which requires most of us (sun or no sun) to take doses of 5000-10,000 IU per day.

Vitamin C and Zinc 

During infection, the concentration of vitamin C in the blood plasma and white blood cells quickly declines. Likewise, zinc deficiency impairs cellular mediators of innate immunity, such as natural killer cell activity, phagocytosis of infectious organisms, and the generation of an oxidative burst.

Supplementation with vitamin C and zinc has been shown to improve various components of the immune system, including natural killer cell activity, migration of white blood cells (chemotaxis), the appropriate and proper proliferation of specific white cells called lymphocytes, and overall antimicrobial activity.

Vitamin C and zinc contribute to the antioxidant status of cells, protecting them against reactive oxygen species. Quercetin, a flavonoid found in fruits and vegetables that has antioxidant properties similar to those of vitamin C, can also benefit specific components of the immune system when supplemented along with zinc.

Both zinc and vitamin C are essential nutrients that play important roles in immune function and help attenuate the risk of infection when taken as dietary supplements. Research shows they reduce the risk, severity, and duration of many infectious diseases. When taking long-term zinc supplementation, make sure you are ingesting enough dietary or supplemental copper.

Zinc dosing: Ideal dosing is about 25-60 mg per day. I take two of these each evening at bedtime, as it can cause nausea when taken during the day.

Vitamin C dosing: Liposomal preparations can be taken in doses up to 3 grams (usually 1 TBSP) per dose without causing gastrointestinal distress. Multiple clinical studies use 1.5 grams 4 times per day (for a total of 6 grams), but this tends to be too inconvenient for most patients of mine. Therefore, I generally recommend 1 TBSP 2x/day during “flu season,” including during this year’s “tripledemic.”  And yes, for those wondering, quercetin is up next.


Quercetin reportedly exerts potent anti-inflammatory effects by inhibiting the production of cytokines, reducing the expression of cyclooxygenase and lipoxygenase enzymes, and maintaining the stability of mast cells, cells responsible for allergies.

In addition, it can reduce the production of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. And there’s more!

Quercetin has been shown to exhibit anti-inflammatory, antioxidant, neuroprotective, and anti-allergic activities. It is often combined with nettles for a more potent “concoction.”

Quercetin dosing: Dosing to suppress inflammatory markers of IL-6 and TNF-alpha are recommended.

A good prophylactic dose of this super immune booster is 500-600 mg per day, which is then doubled for infections.

Multivitamin supplements

Over 10,000 companies sell vitamin supplements. You want to choose GMP-certified and NSF-certified multivitamins that contain antioxidants such as carotenoids (forms of vitamin A), iodine, and selenium. Good MVI supplements also contain polyphenols, which you may recall are needed to “fertilize” your microbiome.

Reishi mushroom extract

Mushrooms contain polysaccharides called beta-glucans, which boost the immune system by enhancing the action of macrophages (a type of white blood cell that kills foreign invaders), activating the “complement” component of the immune system, and boosting natural killer (NK) cell function. The most potent immune-boosting mushroom is Ganoderma lucidum or reishi mushrooms. They are not especially tasty but are used to formulate potent immune-enhancing supplements.

Reishi dosing: Make sure to find a good brand that uses cracked reishi spores to make the powder put in capsules, and take 1000 mg per day.


Melatonin is a potent anti-inflammatory and antioxidant–not simply a sleep aid. The fact that it helps establish our circadian rhythm is a boon to our immune system, as it helps limit tissue damage during an infection. Melatonin does much more than this, but for this article, I’ll state that it’s good for your immune system and will indeed help you sleep more soundly. There’s a good reason that the “expanded” use of melatonin won its scientists the  2017 Nobel Prize in Physiology or Medicine.

Melatonin dosing: Studies have shown that the maximal efficacy (to work up to slowly) occurs at 10-20 mg per night, which would be two to three of these each night.

Nitric Oxide

Nitric oxide (NO) is bactericidal, meaning that it can act directly as an anti-microbial compound that destroys bacteria. Certain families of immune cells called dendritic cells produce NO, contributing to the resolution of both viral and bacterial infections.

The inference in many studies is that increased NO levels contribute to a more rapid and efficient clearing of these pathogens. It’s good for your vasculature and heart – is an immune booster, so it absolutely is on my list.

NO dosing: Find a product like this one with an equal amount of l-arginine and l-citrulline such that you take 1.5 grams of each 2x/day. Alternatively, you can eat a serving of both arugula and beets daily.


The hormone DHEA (dehydroepiandrosterone) is known to positively affect adrenal function, lowering cortisol levels. It has verifiable anti-inflammatory properties and likely supports the immune system via several complex hormonal pathways.

DHEA dosing: Important note: Women with PCOS or a history of breast cancer or men with a history of prostate cancer must take the keto form of this hormone, if at all since the keto form has not been proven to be an immune booster. For dosing of regular DHEA, men should take a daily dose of 50 mg; women-25 mg.

The Research Continues

Most of our organ systems function better when we restore both male hormones and female hormones to youthful levels. This includes identifying premenopausal women with a simple but immune-suppressing low progesterone level.

The alpha-thymosin one peptide is so effective at boosting the immune system (increased natural killer cell activity, increased antibody response to viruses, increased T cell function, and more) that the FDA pulled it off the market from compounding pharmacies so that they could give it to “Big Pharma” to turn into a pricey drug. (Yes, I know!) However, research is ongoing with other peptides.

But it’s not all about peptides. A number of other varieties of mushrooms are currently being investigated for their immune-enhancing properties, including lion’s mane mushrooms. Other medications, such as methylene blue look promising. And the most exciting research involves the use of stem cells and exosomes.


I’m aware that this article contains a great deal of information about not just forever chemicals but of ways you can boost your immune system. Obviously, this immune boosting is helpful “no matter what.” Regarding the chemicals, five big steps would be: cookware, water filtration, indoor air purification, avoidance of fast foods for a plethora of reasons, and consultation with the EWG website to check your personal goods, cosmetics, and so on. Until our government steps it up regarding consumer protections, we need to look out for ourselves.



Introduction to the Vagus Nerve

The vagus nerve is a significant component of the parasympathetic nervous system and plays many roles in the body. It is increasingly recognized as an essential driver of gut-brain axis communication, which may be involved in the pathogenesis of several disorders. This article reviews how this ” long and wandering” nerve works and how its activity can affect health. And yes, I’ll get to the discussion about vagus nerve stimulators after I get through the “why.”

I’ll cover everything from vagus nerve symptoms (from insufficient activity) to discussing how to augment vagal tone to going into actual vagus nerve stimulation. Can’t wait? Do you know why you need VNS but don’t know which device works best? It’s this one. And you can get a nice discount using my code (feel free!): DrKim25. And yes, as you’ll learn, this is the best vagus nerve stimulator currently available without surgery and/or a prescription. First, let me cover the following topics.

  • Basic anatomy and function of the vagus nerve
  • The Autonomic nervous system
  • Specific roles of the vagus nerve in our bodies
  • Heart rate variability
  • Immune and inflammatory mediation
  • The gut-brain-microbiome connection via the vagus
  • The vagal connection to chronic diseases
  • Oxidative stress, inflammation, sympathetic overdrive, and the vagus nerve
  • Methods of improving your vagal tone
  • What you came for: VNS without the work: using a vagus nerve stimulator

The Basic Anatomy and Function of the Vagus Nerve

The vagus nerve, also known as cranial nerve X (10), is the largest nerve in your body. It runs from your brain stem through your neck, chest, and abdomen. The nerve is nicknamed “the Wanderer” (Latin for vagus) because it wanders so far through different organs.

The vagus is a bundle of nerves connecting the brain to several vital organs, including the heart and stomach. It helps regulate several bodily functions and brings stress under control. When its tone (or activity level) is dampened, it impacts vast activities in your body that lead to a decline in health. Supporting and protecting this great “Wanderer” is vital for optimal health. I’ll get into how to do that later in this article.

The vagus nerve is a nerve that maintains homeostasis of the neuro-endocrine-immune systems and controls the parasympathetic (rest, relax, repair) autonomic nervous system. The following section will cover more specifics of the entire autonomic nervous system.

The vagus nerve originates in your brainstem as a pair of nerves, one traveling down the left side of your neck and the other down the right. It then travels down into the trunk of your body, where it innervates (stimulates) your throat and esophagus (the tube that carries food from your mouth to your stomach).

It then wanders downward to innervate your heart (the organ that pumps blood throughout the body), lungs (organs that extract oxygen from the air), liver (the inner organ that removes toxins from the blood), and spleen (the organ that produces immune cells).

Next, it stimulates your pancreas (the organ that produces insulin), stomach (holding chamber for food), gallbladder (small organ next to the liver that stores bile), urinary bladder (vessel holding urine before disposal) and kidneys (the inner organ that filters excess water from blood).

Its last stop is in your small intestine (the tube connecting the stomach to the large intestine) and the first part of the colon (the large intestinal tube storing waste before disposal).

This master nerve is a two-way communication system that relays information from your brain to your internal organs and back again. This nerve accounts for about 80 percent of the fibers that carry information upward to the brain and 20 percent of those that carry information downward from the brain to your internal organs.

The vagus nerve helps control heartbeat, heart rate, and respiration. It affects blood pressure by modulating vasodilation. It is a vital part of the parasympathetic nervous system (PSNS) and other nerves that support “rest-and-digest” activities such as digestion, sexual arousal, and reproduction. It helps balance against sympathetic (fight, flight, stress) nervous system tone.

Consequently, it buffers against stress-related hormones and inflammatory compounds. Now, I’d like to give you a general idea of the autonomic nervous system.

How Does the Autonomic Nervous System Work?

To understand the workings of the vagus nerve, it is first essential to know how the entire autonomic nervous system works. The ANS is comprised of two sides that usually work in opposition. (We are not including the recently described enteric system in this article).

These two sides are the sympathetic and the parasympathetic arms. The autonomic features of the stress response are mediated by the sympathetic arm, which is sometimes called the fight, flight, or freeze response due to the bodily changes needed to enable you to defend yourself physically, run away from danger, or even freeze in total panic.

The other arm of the ANS, the parasympathetic, is the rest, digest, relax, and restore mode. If that sounds more fun, it is in the sense that it’s what is dominant when relaxing on a couch, meditating in your favorite chair, or socializing with friends.

In this state, your body slows down, heals, and returns to homeostasis. Your organs, including your brain, stick to their maintenance schedules, and everything feels fine.

It is often helpful to think of the sympathetic and parasympathetic nervous systems as gears in a car. The sympathetic gear is responsible for speeding up a car when it is in danger or when the driver wants to overtake, but it also leads to wear and tear over time if used too much. The parasympathetic gear keeps the car running smoothly by slowing down when necessary and stopping other parts from overworking themselves.

In response to danger, the sympathetic arm of the autonomic nervous system activates the body’s inflammatory response–a process that usually causes immune cells to produce cytokines and other chemicals that trigger inflammation. Clinical studies have shown that stress and other stimuli can cause flare-ups in autoimmune diseases, accelerate neurodegenerative disorders, exacerbate atherosclerotic plaque formation, worsen asthma symptoms, and even lead to cancer recurrences.

The many roles of the Vagus Nerve

The vagus nerve stimulates organs throughout the body. Scientific research has focused on its connection to the gut, brain, and immune system–areas where vagus nerve stimulation has been shown to provide benefits. We’ll discuss those three areas in detail, but first, let’s look at some other systems that can be affected by low vagus nerve activity, which produces what some people call vagus nerve symptoms.

Mouth and Ears

The vagus nerve helps control taste and saliva in the tongue, tears in the eyes, and hearing in the ear. Scientists are studying whether ear stimulation can activate the vagus nerve while affecting tinnitus. Thus far, auricular vagal stimulators are considerably less effective than externally applied stimulating devices.

Kidney and Bladder

Some research suggests that the vagus nerve promotes general kidney function by helping to control blood glucose and increasing blood flow, which improves blood filtration. Vagus activation likely also releases dopamine in the kidneys, which helps excrete sodium and, therefore, lower blood pressure. However, the mechanism is not fully clear in humans; more studies are needed.

The vagus nerve innervates the bladder. A potential side effect of its stimulation is urinary retention. On the other hand, less vagus stimulation may make people urinate more frequently.

Although there are no good clinical studies on this topic, some practitioners hypothesize that their patients who complain about frequent urination may have a vagus nerve issue in combination with other factors such as low vasopressin (ADH) and low aldosterone as well as high cortisol.


In the spleen, vagal activation can reduce inflammation. It is thought that vagal activation may affect various organs by releasing acetylcholine. However, when it activates in the spleen, its response is believed to be via reduced inflammatory cytokine production.

Liver, Pancreas, and Gallbladder

Glucagon is a pancreatic hormone released via vagal stimulation that acts as a counter-regulatory hormone to insulin. It opposes insulin by stimulating the breakdown of glycogen and triglycerides.

Glucagon also stimulates the release of bile from the gallbladder, which helps break down fat and absorb fat-soluble vitamins.

Female Reproductive Organs

The vagus nerve may affect a woman’s fertility and orgasms by connecting to the cervix, uterus, and vagina. However, since most of what we know about the effects of the vagus nerve on women comes from animal studies, many questions about its impact on male and female reproductive human health remain unanswered.


In the heart, it controls blood pressure, and something you may have heard about as an app-driven buzzword: heart rate variability. Recent studies reveal that an overactive sympathetic nervous system will lessen heart rate variability (HRV).

HRV and Sympathetic Overdrive

Most studies have found that heart rate variability (HRV) is affected by stressful situations. Low parasympathetic activity, a decrease in the vagus nerve activity, has been reported as a factor related to changes in HRV variables. Neuroimaging studies suggest that HRV may be linked to brain regions that evaluate or appraise stressful situations (e.g., the ventromedial prefrontal cortex).

The current neurobiological evidence suggests that stress impacts heart rate variability and supports its use for objectively assessing psychological health and so-called “stress levels.”

Heart rate variability can be measured using an app. This provides insight into the connection between vagal nerve tone and heart rhythm. The bottom line: high levels of heart rate variability are associated with good health and low levels are linked with poorer health.

Some people call these vagus nerve symptoms, even though the symptoms are due to a reduction in vagal activity. Next, let’s revisit some areas where high vagal tone and high HRV are beneficial.

Epidemiological evidence indicates inverse associations between vagal nerve activity, HRV, and metabolic syndrome.

High HRV is associated with a reduced risk of overall mortality and reduced risk of cancer death.

A meta-analysis of 21 studies found that myocardial infarction patients with low HRV­ had approximately four times the mortality risk compared to those with high HRV.

A 2012 meta-analysis of studies on high heart rate variability (HRV) and survival in cancer patients revealed a statistically significant association between HRV and more prolonged survival, particularly in pancreatic cancer patients. A separate study found that the association was mediated by reduced inflammation.

Low HRV is also associated with complications in COPD.

HRV is inversely related to insulin resistance and HbA1C levels, indicating diabetes severity and potential complications.

Its ease of measurement and independent prognostic role suggest that health policymakers should consider routinely implementing this biomarker to predict and prevent major diseases. More on this is coming, but first, let’s turn to the next important area where the research has borne out the benefits of increased vagal tone.

Immune System Function and Inflammation Management

The vagus nerve directs immune activity, suppressing pro-inflammatory cytokines (chemical messengers) produced by immune cells in the spleen. This helps manage inflammation from the respiratory tract and throughout the body’s immune system. We’ll get deeper into the inflammation part later in this article.

The following section will discuss a different mechanism for reducing inflammation by stimulating the gut. Regular vagal nerve activity dampens pain signals in the brain and spine and reduces pain-related behavior. We will expand on this concept later when we discuss vagus nerve stimulation.

Gut-brain-microbiome communication via the vagus nerve

The brain, gut, and microbiota communicate through the microbiota-gut-brain axis in a bidirectional way that involves the autonomic nervous system. The vagus nerve (V.N.), which transmits information from the brain to many organs, is a mixed nerve composed of 80% afferent and 20% efferent fibers.

The V.N., because of its role in interoceptive awareness, can sense the microbiota metabolites through its afferents and transfer this information to the central nervous system, where it is integrated into the leading autonomic network.

A cholinergic anti-inflammatory pathway has been described through vagal fibers, which can dampen peripheral inflammation and decrease intestinal permeability. This may very well modulate the composition of microbiota and aid in healing “leaky gut.”

In contrast, stress (and its accompanying high cortisol) inhibits the vagus nerve, which can harm the gastrointestinal tract and the microbiota. Stress is involved in the pathophysiology of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), both characterized by dysbiosis and gut hyperpermeability.

Next up: how the vagus nerve protects my favorite organ: the brain.

The Vagus-Gut-Brain Connection

 The vagal nerve regulates the communication between the brain and the gut microbiome, which is affected by gut flora. The vagus nerve can distinguish between beneficial and potentially pathogenic bacteria in the gut, which modulate immune-inflammatory activity.

Research has shown that the healthy balance of gut flora and probiotics influences the brain-gut axis. A healthy gut microbiome promotes positive mood and cognitive functions via the vagus nerve cholinergic anti-inflammatory pathway. An imbalanced gut flora stresses vagal activity, which enables negative mood stress and cognitive challenges, including symptoms resembling ADHD.

Vagus Nerve Symptoms= Chronic Diseases

Symptoms and disorders listed below have been associated with vagus nerve dysfunction in various and sometimes limited studies. These are the ones worth listing and watching closely.

  • IBS and IBD
  • Seizures
  • Chronic Pain
  • Depression
  • Sleep disturbances and insomnia
  • Chronic fatigue
  • Cognitive impairment
  • High or low heart rate (and, of course, HRV)
  • Gastroparesis, also known as delayed gastric emptying
  • Chronic inflammation
  • Immune dysfunction
  • Obesity and weight gain
  • Anxiety
  • Chronic degenerative diseases associated with inflammation and oxidative stress are two of the root causes of all chronic diseases. I’ll explain the vagus connection below.

Chronic Disease and the Vagus Nerve

Unlike during the centuries that have preceded us, chronic, degenerative diseases now claim more lives than infectious diseases. Shifting our focus to addressing the root causes of these chronic diseases would save countless lives and alleviate significant suffering. Examples of this include the following:

Major non-communicable causes of death include stroke, cancer, coronary heart disease and its risk factors, and pulmonary conditions. Many risk factors (standard American diets, smoking, lack of exercise, and surprisingly, pollution!) account for many of them. Further, many of these diseases have common underlying biological causes, as shown below. The following discussions include a deep dive into inflammation, oxidative stress, and the role of the autonomic nervous system. Let’s start with oxidative stress.

Oxidative Stress and Chronic Diseases

Oxidation is a chemical reaction in which one or more electrons are added to or removed from an atom. Oxidative stress occurs when the body has more pro-oxidants than antioxidants, leading to DNA damage and diseases.

Oxidative stress is essentially the lack of sufficient antioxidant vitamins (e.g., carotenoids, active forms of vitamin E, vitamin C, and so on). So, you can think of oxidative stress as a lack of sufficient antioxidants, corrected by ingesting enough. Not to be confused with oxidative stress is psychological stress. But, yes, you guessed it, enough psychological stress can deplete antioxidants and cause oxidative stress!

Studies show a correlation between job-related psychological stress and levels of oxidative stress. Furthermore, chronic stress was related to shorter telomeres, which predict disease onset and earlier death. More specifically related to oxidative stress, higher effort-reward imbalance at work–a marker of chronic work stress–was associated with even higher levels of oxidative stress in several clinical studies.

Inflammation and Chronic Diseases

Inflammation is a complex process triggered by various danger signals, including cell damage and infection. Chronic inflammation helps cancer cells escape from apoptosis (programmed cell death) and proliferate, which can lead to metastasis.

Inflammation contributes to the development of atherosclerosis by recruiting macrophages from the bloodstream to form plaques, creating instability in atherosclerotic plaques by stimulating smooth muscle cells to grow within the lesions and promoting plaque rupture with resultant thrombosis.

Inflammation significantly contributes to insulin resistance, one of the main factors underlying diabetes.

Finally, psychosocial stress contributes to elevated pro-inflammatory cytokines and reduced anti-inflammatory cytokines in certain individuals. This imbalance can lead to chronic inflammation, which underlies multiple non-communicable chronic diseases. Now, let’s turn back to the part of the autonomic nervous system we discussed earlier that can cause problems when it’s in the “on position” for too long.

Excessive Sympathetic Nervous System Activity and Chronic Diseases

Excessive activity of the sympathetic nervous system is related to cardiovascular disease by increasing the heart’s oxygen demand, causing vasoconstriction, which can lead to ischemia. High SNS activity also affects the direction in which cancer cells will metastasize.

In addition, studies have found that excessive sympathetic activity is associated with an increased risk of cerebral and cardiovascular events in diabetic patients. Additionally, job stress is associated with higher SNS activity among bus drivers. A study on job stress in bus drivers found that driving in peak traffic was associated with elevated catecholamines–neurohormones secreted by the sympathetic nervous system.

Worth mentioning here is that excessive sympathetic activity worsens sleep, lowers hormone levels such as progesterone, and reduces feelings of well-being and the ability to concentrate, all of which are associated with excess mortality. This sympathetic nervous system over-activity translates to feelings of being stressed. But can “stress” cause all of these problems? Turns out, yes, it can.

Let’s talk about stress.

You know by now that “stress” means overactivity of the sympathetic nervous system. Most of us know how that feels, and it’s not pleasant. Acute stress causes symptoms such as a tight, dry throat and stomach, rapid heartbeat, and shallow breaths. It also induces metabolic changes, immune system reactions, and more.

Stress is not a disease or medical condition in and of itself, but it can exacerbate existing conditions or make predispositions to them worse. Whether you experience stress from constantly having to deal with emergent situations at home or work or (for example)- you’re a doctor who treats patients suffering from the consequences of stress, we have all experienced feelings of stress.

Short periods of stress, like strenuous exercise, doing the NYT crossword puzzle, or taking care of a seriously ill patient, can be good for us. Your brain and body work best when the autonomic nervous system cycles easily and rapidly from sympathetic to parasympathetic control.

However, the problem becomes more serious when chronic stress becomes a constant in your life. When this happens, your body never has a chance to switch back to its normal state of homeostasis entirely. This leads to dysregulation of your organs (primarily caused by innate immune cells), which disrupts all the tasks associated with maintaining proper bodily function.

Instead, these cells remain inflamed for too long and, as a result, lose their ability to return to their original state of homeostasis. This then sets the stage for the short-term (and long-term) effects of “too much sympathetic activity”-or simply too much prolonged stress.

That’s when we initially see insomnia, headaches, anxiety, and depression. Eventually, we see autoimmunity, heart attacks, strokes, dementia, and cancer if our stress becomes chronic. It’s obvious: we need to “manage” our stress and address our oxidative stress and inflammation to escape the ravages of chronic degenerative disease.

A Quick Word about Sleep

Although public health experts have been telling us we need a nightly 7-8 hours of quality sleep, this is achieved by only slightly more than half of the U.S. population. We get into bed and turn on phones, tablets, or (horrors!) television. We revisit the events of the day. We have LED’s in the bedroom. We have pets in the bedroom who can interrupt (or enhance, as in my case) our sleep. We know sleep is essential, but why?

There are plenty of reasons, but I’ll focus on what I believe to be the most essential functions of sleep. It’s when the brain does its repair work, using its unique glymphatic system to clean up damaged (and then inherently inflammatory) brain cells. This is also the optimal time for neurogenesis- when we convert our neural stem cells to neurons and create new neuronal connections.

Sleep is also the time when memories get consolidated in the hippocampus. Deep sleep (check that Oura ring!) boosts the immune system, helps weight loss due to several biochemical pathways, and aids in post-workout muscular recovery.

If you’re not sleeping well, chances are that your sympathetic nervous system is involved (and acting up), which means (obviously) that sleeping pills are not “the answer.” What is? You can now answer that question yourself-it’s stimulation of the parasympathetic nervous system. And yes, we’ll get to that, but first, let’s revisit the concept of taking care of a fair amount of oxidative stress, inflammation, and excess sympathetic activity in one fell swoop.

The Vagus Nerve Inhibits Oxidative Stress, Inflammation, and Sympathetic Activity

Now that we’ve covered the basics of sleep and stress (both worsened by the three things that are associated with all chronic diseases (including insomnia and anxiety), let’s talk about how we can get at least some levels of oxidative stress, inflammation, and excess sympathetic activity under a bit of control.

Research has shown that the vagus nerve inhibits all three major disease-promoting biological factors. For example, a study found that vagus nerve stimulation (VNS) reduces oxidative stress. More recently, scientists found that VNS reduced protein oxidation after myocardial infarction, thus limiting heart damage.

Second, the vagus nerve plays a crucial role in neuroimmune communication. It informs the brain about low-level inflammation through its receptors for interleukin-1 (IL-1), a cytokine involved in inflammatory immune responses.

Notably, the vagus nerve inhibits inflammation by activating the hypothalamic pituitary adrenal axis and the splenic nerve. The first mechanism reduces inflammation by secreting cortisol into the bloodstream, while the second works via cholinergic and noradrenergic signals that trigger specific splenic T-cells.

T-cells secrete acetylcholine, which then binds to the alpha-7 nicotinic acetylcholine receptor on monocytes. This causes an inhibition of inflammatory cytokine synthesis. These two routes constitute the vagal anti-inflammatory reflex.

Third, the vagus nerve plays a significant role in the parasympathetic nervous system, which inhibits sympathetic activity. The vagus nerve specifically increases coronary blood flow by stimulating vasoactive intestinal peptide production, which increases vasodilation.

Anti-hypoxic factors are vital in reducing the risk of cardiovascular disease, stroke, and even cancer since many tumors flourish in hypoxic conditions, and hypoxia is prognostic in cancer.

There is evidence that hypoxia (related to excessive sympathetic vasoconstrictive activity), oxidative stress, and inflammation are causally related to a vicious circle. The vagus nerve inhibits all three promoters of the major chronic diseases mentioned above, and empirical evidence supports this relationship.

All this being said, most highly inflammatory diseases such as mold and mycotoxin illness or CIRS, autoimmune diseases, cancer, and most neurodegenerative diseases require more than VNS to get O.S. and inflammation under control.

Now that you know you should learn how to stimulate your parasympathetic nervous system, specifically your vagus nerve, let’s look at how to do this daily.

Vagus Nerve Stimulation


Research suggests that at least three types of meditation may stimulate the vagus nerve indirectly. Loving-kindness meditation, mindfulness meditation, and Om chanting (T.M.) have all been linked to increased heart rate variability (HRV), which is associated with vagal tone, as you now know.


According to one study on ten healthy people, when the body adjusts to cold temperatures, your fight-or-flight (sympathetic) system declines, and your rest-and-digest (parasympathetic) system increases, which is mediated by the vagus nerve. In this study, temperatures of 50°F were considered cold.

Other studies have shown the benefits of living in Finland, where ice swimming and cold plunges keep everyone slightly healthier.

Cold water showers, ice baths (brrrrrr!), cold plunges, and even cold water or ice packs to the face activate the vagus nerve. To get started on this practice, which is incidentally great for your mitochondrial health, finish your daily shower with 30-60 seconds of cold water on the back of your neck. Even I can do this!

Positive Thoughts and Social Connections

Research suggests that positive emotions and social connections improve overall physical health.

In a study published in 2014, 65 participants were divided into two groups: one group was instructed to sit quietly and think compassionately about others by silently repeating phrases like “May you feel safe” and “May you feel healthy,” while the other group did not receive any special instruction.

After participating in the mindfulness meditation course, active participants reported overall improvements in positive emotions. These emotional and psychological changes were correlated with a greater sense of connectedness to others and an improvement in vagal function as measured by heart-rate variability.


I’ve always bought into the adage that “laughter is the best medicine,” even before knowing the physiology of why that is. That said, studies are not numerous nor conclusive. But somehow, we all know this, right?

Several studies suggest that laughter does indeed stimulate the vagus nerve. One study done in a yoga class where participants were allowed to laugh demonstrated that the “laughter group” experienced increased HRV compared to the control group. I have a powerful urge to tell you a funny joke, but I will resist for now.

Singing or Chanting

Heart rate variability has many beneficial effects, including stress resilience and adaptation, relaxation, and increased parasympathetic activity.

One intriguing study on healthy 18-year-olds shows that singing increases Heart Rate Variability (HRV).

The study’s authors found that humming, hymn singing, mantra chanting, and upbeat, energetic singing all increase heart rate variability slightly differently while still involving the vagus nerve.

Finally, singing in unison, often done in synagogues, mosques, and churches, also increased heart rate variability (HRV) and vagus function in this study.

Deep and Slow Breathing

First, let me define what is meant by deep belly breathing. You can do it immediately when you feel the lump in your throat or the rapid ticking of your heart.

Here’s how: Inhale through your nose for 5 seconds. Hold for 5 seconds. Then exhale for 5 seconds out through your mouth. Do this ten times.

Breathing deeply activates the vagus nerve and parasympathetic nervous system. Shallow breaths through the chest and upper body do not activate these systems.


Studies have found that yoga increases the vagus nerve and parasympathetic system activity.

A 12-week yoga intervention was more strongly associated with improvements in mood and anxiety than walking exercises, which served as the control group. The study found increased thalamic GABA levels in participants who underwent yoga, which is associated with improved mood and decreased anxiety.

Yoga appears to have a positive effect on mental and physical health. However, further research is needed to determine the impact of yoga on vagus nerve tone.


Emerging evidence suggests that the gut microbiota may affect brain function. The gut’s nervous system connects to the brain via the vagus nerve, a pathway known as “the interface of the microbiota-gut-brain axis.”

In a study on mice, supplementation with the probiotic Lactobacillus rhamnosus resulted in positive changes in GABA receptors mediated by the vagus nerve.

Research has shown that the vagus nerve, which (as you recall) connects the brain and the digestive tract, might be stimulated by Lactobacillus rhamnosus (a probiotic). This potential link between L. rhamnosus and enhanced GABA activity adds to emerging evidence about probiotics’ potential health benefits.

  A deeper dive into Probiotics and GABA

GABA is the primary inhibitory neurotransmitter in the central nervous system and regulates many physiological and psychological processes. Yes, it is the “anxiety neurotransmitter” (if its levels get too low), but it’s much more than simply that.

Studies have found that altered GABA receptor expression may play a role in the development of anxiety and depression, which are highly comorbid with both functional and inflammatory bowel disorders such as Ulcerative Colitis.

In one well-done study, scientists demonstrated that treatment with L. rhamnosus induced brain-region-dependent increases in GABA mRNA in the brains of mice compared with control-fed mice.

Notably, the probiotic L. rhamnosus reduced stress-induced levels of cortisol, as well as anxiety- and depression-related behavior in mice. Moreover, these changes were not found in vagotomized mice, identifying the vagus nerve as a significant modulatory communication pathway between gut bacteria and the brain.

The findings suggest that bacteria play an essential role in the bidirectional communication of the gut–brain axis and could prove helpful in treating stress-related disorders such as anxiety and depression.


A moderate-to-deep pressure massage may activate the vagus nerve. In one study, infants received regular and full massages. These massages helped infants gain weight by stimulating the gut, attributed mainly to vagus nerve activation.

While the evidence is scant, the anecdotal reports are astounding for good old foot massages. In particular, Reflexology foot massages are also thought to increase heart rate variability (and hence vagal tone) while lowering heart rate and blood pressure. This is according to a tiny study on healthy people and another on patients with heart disease.


The vagus nerve activates the muscles in the back of the throat that allow you to gargle. The cranial nerve involved is called the hypoglossal nerve, which runs adjacent to the vagus in the back of the throat.

Gargling contracts these throat muscles, which may activate the vagus nerve.

Sleeping or Lying on Your Right Side

Limited studies suggest that laying on your right side increases heart rate variability and vagus activation more than on your left side. One study found that lying on one’s back led to the lowest vagus activation. If all of this sounds a bit exhausting, you’re in luck! I’m not telling you to avoid healthy foods, activities, stress management, and proper sleep, but I am telling you that you can avoid being fixated on your vagal tone all day. Here’s how.

VNS health benefits

If you don’t have time to do deep breathing, meditation, or any of the things listed above to deal with your vagus nerve symptoms, read on; I’ve got “just the thing” for you coming up soon. Yes, I’ll pre-empt myself: it’s the best vagus nerve stimulator that “has everything” going for it. It works, it’s inexpensive, and it’s a quick usage session. First, let’s see how this device even came to be.

Vagus nerve stimulation (VNS) was developed in the 19th century. Although it did not work well initially, it led to many VNS-related animal studies for seizure control.

Since the 1990s, several early clinical trials have proven the effectiveness of vagus nerve stimulation (VNS) in treating refractory epilepsy and depression. Implantable devices are designed to automate seizure control and for use in heart failure.

Noninvasive transcutaneous vagus nerve stimulators, which stimulate a branch of the auricular vagus nerve, or externally applied devices that work by holding them near the carotid artery-vagus intersection are also undergoing clinical trials for the treatment of epilepsy, pain, inflammation, headache, and much more. These noninvasive VNS devices exhibit greater safety profiles than their invasive counterparts. Speaking of inflammation and brains, let’s take a closer look.

Vagus nerve stimulation for Inflammation and Brain Health

Vagus nerve stimulation (VNS), a stimulating electrode placed on the vagus nerve (in the neck) to deliver low-frequency, intermittent electrical pulses, is approved for refractory depression by the FDA.

VNS affects many brain regions, including those involved in depressive pathology and neurotransmitters such as serotonin and norepinephrine. Research shows that VNS may affect signal transduction mechanisms, including brain-derived neurotrophic factor (BDNF). The exact mechanism of action is unclear at this time.

VNS reduces inflammation by activating the parasympathetic anti-inflammatory pathway, which occurs peripherally (cytokine alterations) and centrally (reduced microglial activation). Stress increases sympathetic excitation, stimulates catecholamine release, and increases brain and peripheral cytokine expression.

The parasympathetic nervous system and acetylcholine release have been shown to have anti-inflammatory effects, which may be responsible for the approximately 50% two-year remission rate for refractory depression with continual, daily use of a vagus nerve stimulator.

Many studies have found that noninvasive vagus nerve stimulation is as effective as direct electrical stimulation for treating refractory epilepsy, pain, Alzheimer’s disease, pain, depression, anxiety, and more.

Autoimmune Disease Potential

Because this is the main focus of my clinical practice, I’d like to give a shout-out to treating autoimmune disorders.

The autonomic nervous system is commonly out of balance in many chronic autoimmune diseases, including rheumatoid arthritis (R.A.), a prototypical immune-mediated inflammatory disease.

Scientists have recently discovered that autonomic dysfunction precedes and predicts the development of symptomatic and seropositive rheumatoid arthritis (R.A.) in people at risk for developing R.A. In addition, R.A. patients with relatively high vagus nerve tone (measured by heart rate variability) respond better to antirheumatic therapies.

These data suggest that a vagus nerve stimulator may help control human inflammation. Experimental studies in animal models of R.A. support this notion by showing that stimulation of the cholinergic anti-inflammatory pathway by efferent electrical vagus nerve stimulation improves clinical signs and symptoms of arthritis, reduces cytokine production, and protects against progressive joint destruction.

The results of these studies, along with previous research in animal models of inflammation, provided the rationale for experimental clinical trials in patients with rheumatoid arthritis. A vagus nerve stimulator has been demonstrated to inhibit human peripheral blood cytokine production.

These studies show that a vagus nerve stimulation device can reduce the production of inflammatory cytokines and improve disease severity in patients with rheumatoid arthritis- even those resistant to other forms of treatment. This work supports further studies using a bioelectronic approach to help treat perhaps all autoimmune disorders.

Takeaway Advice

 Let’s talk about how we all “live” for the most part. We try to eat healthfully, get enough sleep, and exercise, but few of us take the time to lower our stress levels. If you look at national statistics on what foods are consumed, what we collectively weigh, how much we sleep (thank you, Oura rings), and exercise, we’re a bit pathetic. Studies hint that most of us live in a stressed, sympathetic nervous system-driven state most of the time.

Ideally, we’d get all these healthy activities and meditation done daily. We’d also regularly have fun with oxytocin-enhancing friend-and-family bonding. And we’d go back to the list in the middle of this article, choosing vagus-stimulating activities to do daily. Yeah, right, you’re busy enough, you are all thinking. Agreed! So what do we do?

Whatever we all do, you now know we need to ensure that our autonomic nervous system is driven by the parasympathetic, not the sympathetic side.

Twenty years ago, getting VNS required an implantable device=surgery. As little as five years ago, it would have required a prescription. Now, we can purchase a VNS health device because we are informed and want one. The best vagus nerve stimulator is small, easy to use, and it just takes two minutes, twice daily, to get the fantastic results described in this article. And no, it won’t cure cancer, but it sure can make you feel much more “chill.” And, of course, lots more than that.

Emerging research suggests that optimizing the vagus nerve’s functioning can help with various health issues, including digestion, mental health, cognitive health, metabolic health, autoimmune disease, and inflammatory disease. And yes, since fat cells are inflammatory, this does indeed help augment weight loss.

More human research is needed to verify and better understand these connections and how the “wandering” vagus nerve impacts overall health, but make no mistake: your health depends on where you “live” regarding your autonomic nervous system. Not just any vagus nerve stimulator is going to cut it. The auricular devices only capture a tiny branch of the vagus nerve. Only one non-prescription item on the market works externally: this particular vagus nerve stimulation device.

Use my discount code: DrKim25, and then use your chosen (and inexpensive!) vagus nerve stimulation device twice daily, in good health!


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