Akash Goel, MD

From Ayurveda to the teachings of Hippocrates, medicine’s earliest traditions advanced a belief that the gut was the foundation of all health and disease. It wasn’t until recently, however, that Western medicine has adopted the notion of gut-barrier dysfunction as a pathologic phenomenon critical to not only digestive health but also chronic allergic, inflammatory, and autoimmune disease.

To learn more, Medscape contributor Akash Goel, MD, interviewed Elena Ivanina, DO, MPH, an integrative gastroenterologist, on the role of the gut barrier. Dr. Ivanina is the founder of the Center for Integrative Gut Health and the former director of Neurogastroenterology and Motility at Lenox Hill Hospital in New York. She runs the educational platform for all things gut health, gutlove.com.

What is the role of the gut barrier in overall health and disease?

The gut contains the human body’s largest interface between a person and their external environment. The actual interface is at the gut barrier, where there needs to be an ideal homeostasis and selectivity mechanism to allow the absorption of healthy nutrients, but on the other hand prevent the penetration of harmful microbes, food antigens, and other proinflammatory factors and toxins.

The gut barrier is made up of the mucus layer, gut microbiome, epithelial cells, and immune cells in the lamina propria. When this apparatus is disrupted by factors such as infection, low-fiber diet, antibiotics, and alcohol, then it cannot function normally to selectively keep out the harmful intraluminal substances.

Gut-barrier disruption leads to translocation of dangerous intraluminal components, such as bacteria and their components, into the gut wall and, most importantly, exposes the immune system to them. This causes improper immune activation and dysregulation, which has been shown to lead to various diseases, including gastrointestinal inflammatory disorders such as inflammatory bowel disease (IBD) and celiac disease, systemic autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, and metabolic diseases such as obesity and diabetes.



Is disruption of this barrier what is usually referred to as “leaky gut”?

Leaky gut is a colloquial term for increased intestinal permeability or intestinal hyperpermeability. In a 2019 review article, Dr. Michael Camilleri exposes leaky gut as a term that can be misleading and confusing to the general population. It calls upon clinicians to have an increased awareness of the potential of barrier dysfunction in diseases, and to consider the barrier as a target for treatment.



Is leaky gut more of a mechanism of underlying chronic disease or is it a disease of its own?

Intestinal permeability is a pathophysiologic process in the gut with certain risk factors that in some conditions has been shown to precede chronic disease. There has not been any convincing evidence that it can be diagnosed and treated as its own entity, but research is ongoing.

In IBD, the Crohn’s and Colitis Canada Genetic, Environmental, Microbial Project research consortium has been studying individuals at increased risk for Crohn’s disease because of a first-degree family member with Crohn’s disease. They found an increased abundance of Ruminococcus torques in the microbiomes of at-risk individuals who went on to develop the disease. R. torques are mucin degraders that induce an increase in other mucin-using bacteria, which can contribute to gut-barrier compromise.

In other studies, patients have been found to have asymptomatic intestinal hyperpermeability years before their diagnosis of Crohn’s disease. This supports understanding more about the potential of intestinal hyperpermeability as its own diagnosis that, if addressed, could possibly prevent disease development.
 

The many possible sources of gut-barrier disruption

What causes leaky gut, and when should physicians and patients be suspicious if they have it?

There are many risk factors that have been associated with leaky gut in both human studies and animal studies, including acrolein (food toxin), aging, alcohol, antacid drugs, antibiotics, burn injury, chemotherapy, circadian rhythm disruption, corticosteroids, emulsifiers (food additives), strenuous exercise (≥ 2 hours) at 60% VO₂ max, starvation, fructose, fructans, gliadin (wheat protein), high-fat diet, high-salt diet, high-sugar diet, hyperglycemia, low-fiber diet, nonsteroidal anti-inflammatory drugs, pesticide, proinflammatory cytokines, psychological stress, radiation, sleep deprivation, smoking, and sweeteners.

Patients may be completely asymptomatic with leaky gut. Physicians should be suspicious if there is a genetic predisposition to chronic disease or if any risk factors are unveiled after assessing diet and lifestyle exposures.



What is the role of the Western diet and processed food consumption in driving disruptions of the gut barrier?

The Western diet reduces gut-barrier mucus thickness, leading to increased gut permeability. People who consume a Western diet typically eat less than 15 grams of fiber per day, which is significantly less than many other cultures, including the hunter-gatherers of Tanzania (Hadza), who get 100 or more grams of fiber a day in their food.

With a fiber-depleted diet, gut microbiota that normally feed on fiber gradually disappear and other commensals shift their metabolism to degrade the gut-barrier mucus layer.

A low-fiber diet also decreases short-chain fatty acid production, which reduces production of mucus and affects tight junction regulation.
 

Emerging evidence on causality

New evidence is demonstrating that previous functional conditions of the gastrointestinal tract, like functional dyspepsia, are associated with abnormalities to the intestinal barrier. What is the association between conditions like functional dyspepsia and irritable bowel syndrome (IBS) with gut-barrier disruption?

Conditions such as functional dyspepsia and IBS are similar in that their pathophysiology is incompletely understood and likely attributable to contributions from many different underlying mechanisms. This makes it difficult for clinicians to explain the condition to patients and often to treat without specific therapeutic targets.

Emerging evidence with new diagnostic tools, such as confocal laser endomicroscopy, has demonstrated altered mucosal barrier function in both conditions.

In patients with IBS who have a suspected food intolerance, studies looking at exposure to the food antigens found that the food caused immediate breaks, increased intervillous spaces, and increased inflammatory cells in the gut mucosa. These changes were associated with patient responses to exclusion diets.

In functional dyspepsia, another study, using confocal laser endomicroscopy, has shown that affected patients have significantly greater epithelial gap density in the duodenum, compared with healthy controls. There was also impaired duodenal-epithelial barrier integrity and evidence of increased cellular pyroptosis in the duodenal mucosa.

These findings suggest that while IBS and functional dyspepsia are still likely multifactorial, there may be a common preclinical state that can be further investigated as far as preventing its development and using it as a therapeutic target.



What diagnostic testing are you using to determine whether patients have disruptions to the gut barrier? Are they validated or more experimental?

There are various testing strategies that have been used in research to diagnose intestinal hyperpermeability. In a 2021 analysis, Dr. Michael Camilleri found that the optimal probes for measuring small intestinal and colonic permeability are the mass excreted of 13C-mannitol at 0-2 hours and lactulose during 2-8 hours or sucralose during 8-24 hours. Studies looking at postinfectious IBS have incorporated elevated urinary lactulose/mannitol ratios. Dr. Alessio Fasano and others have looked at using zonulin as a biomarker of impaired gut-barrier function. These tests are still considered experimental.



Is there an association between alterations in the gut microbiome and gut-barrier disruption?

There is an integral relationship between the gut microbiome and gut-barrier function, and dysbiosis can disrupt gut-barrier functionality.

The microbiota produce a variety of metabolites in close proximity to the gut epithelium, impacting gut-barrier function and immune response. For example, short-chain fatty acids produced by Bifidobacterium, Bacteroides, Enterobacter, Faecalibacterium, and Roseburia species impact host immune cell differentiation and metabolism as well as influence susceptibility to pathogens.

Studies have shown that sodium butyrate significantly improves epithelial-barrier function. Other experiments have used transplantation of the intestinal microbiota to show that introduction of certain microbial phenotypes can significantly increase gut permeability.
 

Practical advice for clinicians and patients

How do you advise patients to avoid gut-barrier disruption?

It is important to educate and counsel patients about the long list of risk factors, many of which are closely related to a Western diet and lifestyle, which can increase their risk for leaky gut.

Once one has it, can it be repaired? Can you share a bit about your protocols in general terms?

Many interventions have been shown to improve intestinal permeability. They include berberine, butyrate, caloric restriction and fasting, curcumin, dietary fiber (prebiotics), moderate exercise, fermented food, fish oil, glutamine, quercetin, probiotics, vagus nerve stimulation, vitamin D, and zinc.

Protocols have to be tailored to patients and their risk factors, diet, and lifestyle.

What are some tips from a nutrition and lifestyle standpoint that patients can follow to ensure a robust gut barrier?

It is important to emphasize a high-fiber diet with naturally fermented food, incorporating time-restricted eating, such as eating an early dinner and nothing else before bedtime, a moderate exercise routine, and gut-brain modulation with techniques such as acupuncture that can incorporate vagus nerve stimulation. Limited safe precision supplementation can be discussed on an individual basis based on the patient’s interest, additional testing, and other existing health conditions.
 

Dr. Akash Goel is a clinical assistant professor of medicine at Weill Cornell in gastroenterology and hepatology. He has disclosed no relevant financial relationships. His work has appeared on networks and publications such as CNN, The New York Times, Time Magazine, and Financial Times. He has a deep interest in nutrition, food as medicine, and the intersection between the gut microbiome and human health.

A version of this article appeared on Medscape.com.

From Ayurveda to the teachings of Hippocrates, medicine’s earliest traditions advanced a belief that the gut was the foundation of all health and disease. It wasn’t until recently, however, that Western medicine has adopted the notion of gut-barrier dysfunction as a pathologic phenomenon critical to not only digestive health but also chronic allergic, inflammatory, and autoimmune disease.

To learn more, Medscape contributor Akash Goel, MD, interviewed Elena Ivanina, DO, MPH, an integrative gastroenterologist, on the role of the gut barrier. Dr. Ivanina is the founder of the Center for Integrative Gut Health and the former director of Neurogastroenterology and Motility at Lenox Hill Hospital in New York. She runs the educational platform for all things gut health, gutlove.com.

What is the role of the gut barrier in overall health and disease?

The gut contains the human body’s largest interface between a person and their external environment. The actual interface is at the gut barrier, where there needs to be an ideal homeostasis and selectivity mechanism to allow the absorption of healthy nutrients, but on the other hand prevent the penetration of harmful microbes, food antigens, and other proinflammatory factors and toxins.

The gut barrier is made up of the mucus layer, gut microbiome, epithelial cells, and immune cells in the lamina propria. When this apparatus is disrupted by factors such as infection, low-fiber diet, antibiotics, and alcohol, then it cannot function normally to selectively keep out the harmful intraluminal substances.

Gut-barrier disruption leads to translocation of dangerous intraluminal components, such as bacteria and their components, into the gut wall and, most importantly, exposes the immune system to them. This causes improper immune activation and dysregulation, which has been shown to lead to various diseases, including gastrointestinal inflammatory disorders such as inflammatory bowel disease (IBD) and celiac disease, systemic autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, and metabolic diseases such as obesity and diabetes.



Is disruption of this barrier what is usually referred to as “leaky gut”?

Leaky gut is a colloquial term for increased intestinal permeability or intestinal hyperpermeability. In a 2019 review article, Dr. Michael Camilleri exposes leaky gut as a term that can be misleading and confusing to the general population. It calls upon clinicians to have an increased awareness of the potential of barrier dysfunction in diseases, and to consider the barrier as a target for treatment.



Is leaky gut more of a mechanism of underlying chronic disease or is it a disease of its own?

Intestinal permeability is a pathophysiologic process in the gut with certain risk factors that in some conditions has been shown to precede chronic disease. There has not been any convincing evidence that it can be diagnosed and treated as its own entity, but research is ongoing.

In IBD, the Crohn’s and Colitis Canada Genetic, Environmental, Microbial Project research consortium has been studying individuals at increased risk for Crohn’s disease because of a first-degree family member with Crohn’s disease. They found an increased abundance of Ruminococcus torques in the microbiomes of at-risk individuals who went on to develop the disease. R. torques are mucin degraders that induce an increase in other mucin-using bacteria, which can contribute to gut-barrier compromise.

In other studies, patients have been found to have asymptomatic intestinal hyperpermeability years before their diagnosis of Crohn’s disease. This supports understanding more about the potential of intestinal hyperpermeability as its own diagnosis that, if addressed, could possibly prevent disease development.
 

The many possible sources of gut-barrier disruption

What causes leaky gut, and when should physicians and patients be suspicious if they have it?

There are many risk factors that have been associated with leaky gut in both human studies and animal studies, including acrolein (food toxin), aging, alcohol, antacid drugs, antibiotics, burn injury, chemotherapy, circadian rhythm disruption, corticosteroids, emulsifiers (food additives), strenuous exercise (≥ 2 hours) at 60% VO₂ max, starvation, fructose, fructans, gliadin (wheat protein), high-fat diet, high-salt diet, high-sugar diet, hyperglycemia, low-fiber diet, nonsteroidal anti-inflammatory drugs, pesticide, proinflammatory cytokines, psychological stress, radiation, sleep deprivation, smoking, and sweeteners.

Patients may be completely asymptomatic with leaky gut. Physicians should be suspicious if there is a genetic predisposition to chronic disease or if any risk factors are unveiled after assessing diet and lifestyle exposures.



What is the role of the Western diet and processed food consumption in driving disruptions of the gut barrier?

The Western diet reduces gut-barrier mucus thickness, leading to increased gut permeability. People who consume a Western diet typically eat less than 15 grams of fiber per day, which is significantly less than many other cultures, including the hunter-gatherers of Tanzania (Hadza), who get 100 or more grams of fiber a day in their food.

With a fiber-depleted diet, gut microbiota that normally feed on fiber gradually disappear and other commensals shift their metabolism to degrade the gut-barrier mucus layer.

A low-fiber diet also decreases short-chain fatty acid production, which reduces production of mucus and affects tight junction regulation.
 

Emerging evidence on causality

New evidence is demonstrating that previous functional conditions of the gastrointestinal tract, like functional dyspepsia, are associated with abnormalities to the intestinal barrier. What is the association between conditions like functional dyspepsia and irritable bowel syndrome (IBS) with gut-barrier disruption?

Conditions such as functional dyspepsia and IBS are similar in that their pathophysiology is incompletely understood and likely attributable to contributions from many different underlying mechanisms. This makes it difficult for clinicians to explain the condition to patients and often to treat without specific therapeutic targets.

Emerging evidence with new diagnostic tools, such as confocal laser endomicroscopy, has demonstrated altered mucosal barrier function in both conditions.

In patients with IBS who have a suspected food intolerance, studies looking at exposure to the food antigens found that the food caused immediate breaks, increased intervillous spaces, and increased inflammatory cells in the gut mucosa. These changes were associated with patient responses to exclusion diets.

In functional dyspepsia, another study, using confocal laser endomicroscopy, has shown that affected patients have significantly greater epithelial gap density in the duodenum, compared with healthy controls. There was also impaired duodenal-epithelial barrier integrity and evidence of increased cellular pyroptosis in the duodenal mucosa.

These findings suggest that while IBS and functional dyspepsia are still likely multifactorial, there may be a common preclinical state that can be further investigated as far as preventing its development and using it as a therapeutic target.



What diagnostic testing are you using to determine whether patients have disruptions to the gut barrier? Are they validated or more experimental?

There are various testing strategies that have been used in research to diagnose intestinal hyperpermeability. In a 2021 analysis, Dr. Michael Camilleri found that the optimal probes for measuring small intestinal and colonic permeability are the mass excreted of 13C-mannitol at 0-2 hours and lactulose during 2-8 hours or sucralose during 8-24 hours. Studies looking at postinfectious IBS have incorporated elevated urinary lactulose/mannitol ratios. Dr. Alessio Fasano and others have looked at using zonulin as a biomarker of impaired gut-barrier function. These tests are still considered experimental.



Is there an association between alterations in the gut microbiome and gut-barrier disruption?

There is an integral relationship between the gut microbiome and gut-barrier function, and dysbiosis can disrupt gut-barrier functionality.

The microbiota produce a variety of metabolites in close proximity to the gut epithelium, impacting gut-barrier function and immune response. For example, short-chain fatty acids produced by Bifidobacterium, Bacteroides, Enterobacter, Faecalibacterium, and Roseburia species impact host immune cell differentiation and metabolism as well as influence susceptibility to pathogens.

Studies have shown that sodium butyrate significantly improves epithelial-barrier function. Other experiments have used transplantation of the intestinal microbiota to show that introduction of certain microbial phenotypes can significantly increase gut permeability.
 

Practical advice for clinicians and patients

How do you advise patients to avoid gut-barrier disruption?

It is important to educate and counsel patients about the long list of risk factors, many of which are closely related to a Western diet and lifestyle, which can increase their risk for leaky gut.

Once one has it, can it be repaired? Can you share a bit about your protocols in general terms?

Many interventions have been shown to improve intestinal permeability. They include berberine, butyrate, caloric restriction and fasting, curcumin, dietary fiber (prebiotics), moderate exercise, fermented food, fish oil, glutamine, quercetin, probiotics, vagus nerve stimulation, vitamin D, and zinc.

Protocols have to be tailored to patients and their risk factors, diet, and lifestyle.

What are some tips from a nutrition and lifestyle standpoint that patients can follow to ensure a robust gut barrier?

It is important to emphasize a high-fiber diet with naturally fermented food, incorporating time-restricted eating, such as eating an early dinner and nothing else before bedtime, a moderate exercise routine, and gut-brain modulation with techniques such as acupuncture that can incorporate vagus nerve stimulation. Limited safe precision supplementation can be discussed on an individual basis based on the patient’s interest, additional testing, and other existing health conditions.
 

Dr. Akash Goel is a clinical assistant professor of medicine at Weill Cornell in gastroenterology and hepatology. He has disclosed no relevant financial relationships. His work has appeared on networks and publications such as CNN, The New York Times, Time Magazine, and Financial Times. He has a deep interest in nutrition, food as medicine, and the intersection between the gut microbiome and human health.

A version of this article appeared on Medscape.com.

From Ayurveda to the teachings of Hippocrates, medicine’s earliest traditions advanced a belief that the gut was the foundation of all health and disease. It wasn’t until recently, however, that Western medicine has adopted the notion of gut-barrier dysfunction as a pathologic phenomenon critical to not only digestive health but also chronic allergic, inflammatory, and autoimmune disease.

To learn more, Medscape contributor Akash Goel, MD, interviewed Elena Ivanina, DO, MPH, an integrative gastroenterologist, on the role of the gut barrier. Dr. Ivanina is the founder of the Center for Integrative Gut Health and the former director of Neurogastroenterology and Motility at Lenox Hill Hospital in New York. She runs the educational platform for all things gut health, gutlove.com.

What is the role of the gut barrier in overall health and disease?

The gut contains the human body’s largest interface between a person and their external environment. The actual interface is at the gut barrier, where there needs to be an ideal homeostasis and selectivity mechanism to allow the absorption of healthy nutrients, but on the other hand prevent the penetration of harmful microbes, food antigens, and other proinflammatory factors and toxins.

The gut barrier is made up of the mucus layer, gut microbiome, epithelial cells, and immune cells in the lamina propria. When this apparatus is disrupted by factors such as infection, low-fiber diet, antibiotics, and alcohol, then it cannot function normally to selectively keep out the harmful intraluminal substances.

Gut-barrier disruption leads to translocation of dangerous intraluminal components, such as bacteria and their components, into the gut wall and, most importantly, exposes the immune system to them. This causes improper immune activation and dysregulation, which has been shown to lead to various diseases, including gastrointestinal inflammatory disorders such as inflammatory bowel disease (IBD) and celiac disease, systemic autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, and metabolic diseases such as obesity and diabetes.



Is disruption of this barrier what is usually referred to as “leaky gut”?

Leaky gut is a colloquial term for increased intestinal permeability or intestinal hyperpermeability. In a 2019 review article, Dr. Michael Camilleri exposes leaky gut as a term that can be misleading and confusing to the general population. It calls upon clinicians to have an increased awareness of the potential of barrier dysfunction in diseases, and to consider the barrier as a target for treatment.



Is leaky gut more of a mechanism of underlying chronic disease or is it a disease of its own?

Intestinal permeability is a pathophysiologic process in the gut with certain risk factors that in some conditions has been shown to precede chronic disease. There has not been any convincing evidence that it can be diagnosed and treated as its own entity, but research is ongoing.

In IBD, the Crohn’s and Colitis Canada Genetic, Environmental, Microbial Project research consortium has been studying individuals at increased risk for Crohn’s disease because of a first-degree family member with Crohn’s disease. They found an increased abundance of Ruminococcus torques in the microbiomes of at-risk individuals who went on to develop the disease. R. torques are mucin degraders that induce an increase in other mucin-using bacteria, which can contribute to gut-barrier compromise.

In other studies, patients have been found to have asymptomatic intestinal hyperpermeability years before their diagnosis of Crohn’s disease. This supports understanding more about the potential of intestinal hyperpermeability as its own diagnosis that, if addressed, could possibly prevent disease development.
 

The many possible sources of gut-barrier disruption

What causes leaky gut, and when should physicians and patients be suspicious if they have it?

There are many risk factors that have been associated with leaky gut in both human studies and animal studies, including acrolein (food toxin), aging, alcohol, antacid drugs, antibiotics, burn injury, chemotherapy, circadian rhythm disruption, corticosteroids, emulsifiers (food additives), strenuous exercise (≥ 2 hours) at 60% VO₂ max, starvation, fructose, fructans, gliadin (wheat protein), high-fat diet, high-salt diet, high-sugar diet, hyperglycemia, low-fiber diet, nonsteroidal anti-inflammatory drugs, pesticide, proinflammatory cytokines, psychological stress, radiation, sleep deprivation, smoking, and sweeteners.

Patients may be completely asymptomatic with leaky gut. Physicians should be suspicious if there is a genetic predisposition to chronic disease or if any risk factors are unveiled after assessing diet and lifestyle exposures.



What is the role of the Western diet and processed food consumption in driving disruptions of the gut barrier?

The Western diet reduces gut-barrier mucus thickness, leading to increased gut permeability. People who consume a Western diet typically eat less than 15 grams of fiber per day, which is significantly less than many other cultures, including the hunter-gatherers of Tanzania (Hadza), who get 100 or more grams of fiber a day in their food.

With a fiber-depleted diet, gut microbiota that normally feed on fiber gradually disappear and other commensals shift their metabolism to degrade the gut-barrier mucus layer.

A low-fiber diet also decreases short-chain fatty acid production, which reduces production of mucus and affects tight junction regulation.
 

Emerging evidence on causality

New evidence is demonstrating that previous functional conditions of the gastrointestinal tract, like functional dyspepsia, are associated with abnormalities to the intestinal barrier. What is the association between conditions like functional dyspepsia and irritable bowel syndrome (IBS) with gut-barrier disruption?

Conditions such as functional dyspepsia and IBS are similar in that their pathophysiology is incompletely understood and likely attributable to contributions from many different underlying mechanisms. This makes it difficult for clinicians to explain the condition to patients and often to treat without specific therapeutic targets.

Emerging evidence with new diagnostic tools, such as confocal laser endomicroscopy, has demonstrated altered mucosal barrier function in both conditions.

In patients with IBS who have a suspected food intolerance, studies looking at exposure to the food antigens found that the food caused immediate breaks, increased intervillous spaces, and increased inflammatory cells in the gut mucosa. These changes were associated with patient responses to exclusion diets.

In functional dyspepsia, another study, using confocal laser endomicroscopy, has shown that affected patients have significantly greater epithelial gap density in the duodenum, compared with healthy controls. There was also impaired duodenal-epithelial barrier integrity and evidence of increased cellular pyroptosis in the duodenal mucosa.

These findings suggest that while IBS and functional dyspepsia are still likely multifactorial, there may be a common preclinical state that can be further investigated as far as preventing its development and using it as a therapeutic target.



What diagnostic testing are you using to determine whether patients have disruptions to the gut barrier? Are they validated or more experimental?

There are various testing strategies that have been used in research to diagnose intestinal hyperpermeability. In a 2021 analysis, Dr. Michael Camilleri found that the optimal probes for measuring small intestinal and colonic permeability are the mass excreted of 13C-mannitol at 0-2 hours and lactulose during 2-8 hours or sucralose during 8-24 hours. Studies looking at postinfectious IBS have incorporated elevated urinary lactulose/mannitol ratios. Dr. Alessio Fasano and others have looked at using zonulin as a biomarker of impaired gut-barrier function. These tests are still considered experimental.



Is there an association between alterations in the gut microbiome and gut-barrier disruption?

There is an integral relationship between the gut microbiome and gut-barrier function, and dysbiosis can disrupt gut-barrier functionality.

The microbiota produce a variety of metabolites in close proximity to the gut epithelium, impacting gut-barrier function and immune response. For example, short-chain fatty acids produced by Bifidobacterium, Bacteroides, Enterobacter, Faecalibacterium, and Roseburia species impact host immune cell differentiation and metabolism as well as influence susceptibility to pathogens.

Studies have shown that sodium butyrate significantly improves epithelial-barrier function. Other experiments have used transplantation of the intestinal microbiota to show that introduction of certain microbial phenotypes can significantly increase gut permeability.
 

Practical advice for clinicians and patients

How do you advise patients to avoid gut-barrier disruption?

It is important to educate and counsel patients about the long list of risk factors, many of which are closely related to a Western diet and lifestyle, which can increase their risk for leaky gut.

Once one has it, can it be repaired? Can you share a bit about your protocols in general terms?

Many interventions have been shown to improve intestinal permeability. They include berberine, butyrate, caloric restriction and fasting, curcumin, dietary fiber (prebiotics), moderate exercise, fermented food, fish oil, glutamine, quercetin, probiotics, vagus nerve stimulation, vitamin D, and zinc.

Protocols have to be tailored to patients and their risk factors, diet, and lifestyle.

What are some tips from a nutrition and lifestyle standpoint that patients can follow to ensure a robust gut barrier?

It is important to emphasize a high-fiber diet with naturally fermented food, incorporating time-restricted eating, such as eating an early dinner and nothing else before bedtime, a moderate exercise routine, and gut-brain modulation with techniques such as acupuncture that can incorporate vagus nerve stimulation. Limited safe precision supplementation can be discussed on an individual basis based on the patient’s interest, additional testing, and other existing health conditions.
 

Dr. Akash Goel is a clinical assistant professor of medicine at Weill Cornell in gastroenterology and hepatology. He has disclosed no relevant financial relationships. His work has appeared on networks and publications such as CNN, The New York Times, Time Magazine, and Financial Times. He has a deep interest in nutrition, food as medicine, and the intersection between the gut microbiome and human health.

A version of this article appeared on Medscape.com.

If the pandemic served as a window into our health, what it revealed was a U.S. population that is not only sick but also seemingly only getting sicker. Life expectancy is falling precipitously. Three-fourths of Americans are overweight or obese, half have diabetes or prediabetes, and a majority are metabolically unhealthy. Furthermore, the rates of allergic, inflammatory, and autoimmune diseases are rising at rates of 3%-9% per year in the West, far faster than the speed of genetic change in this population.

Of course, diet and lifestyle are major factors behind such trends, but a grossly underappreciated driver in what ails us is the role of environmental toxins and endocrine-disrupting chemicals. In years past, these factors have largely evaded the traditional Western medical establishment; however, mounting evidence now supports their significance in fertility, metabolic health, and cancer.

Although several industrial chemicals and toxins have been identified as carcinogens and have subsequently been regulated, many more remain persistent in the environment and continue to be freely used. It is therefore incumbent upon both the general public and clinicians to be knowledgeable about these exposures. Here, we review some of the most common exposures and the substantial health risks associated with them, along with some general guidance around best practices for how to minimize exposure.
 

Microplastics

“Microplastics” is a term used to describe small fragments or particles of plastic breakdown or microbeads from household or personal care products, measuring less than 5 mm in length.

Plastic waste is accumulating at alarming and devastating proportions – by 2050, it is estimated that by weight, there will be more plastic than fish in the oceans. That translates into 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, plastic exposure has been shown to promote tumorigenesis in animal studies, and in vitro studies have demonstrated the toxicity of microplastics at the cellular level. However, it is not well known whether the plastic itself is toxic or if it simply serves as a carrier for other environmental toxins to bioaccumulate.

According to Tasha Stoiber, a senior scientist at the Environmental Working Group, “Microplastics have been widely detected in fish and seafood, as well as other products like bottled water, beer, honey, and tap water.” The EWG states there are no formal advisories on fish consumption to avoid exposure to microplastics at the moment.

Pressure also is mounting for a ban on microbeads in personal care products.

Until such bans are put in place, it is advised to avoid single-use plastics, favor reusable tote bags for grocery shopping rather than plastic bags, and opt for loose leaf tea or paper tea bags rather than mesh-based alternatives.
 

Phthalates

Phthalates are chemicals used to make plastics soft and durable, as well as to bind fragrances. They are commonly found in household items such as vinyl (for example, flooring, shower curtains) and fragrances, air fresheners, and perfumes.

Phthalates are known hormone-disrupting chemicals, exposure to which has been associated with abnormal sexual and brain development in children, as well as lower levels of testosterone in men. Exposures are thought to occur via inhalation, ingestion, and skin contact; however, fasting studies demonstrate that a majority of exposure is probably food related.

To avoid phthalate exposures, recommendations include avoiding polyvinyl chloride plastics (particularly food containers, plastic wrap, and children’s toys), which are identifiable by the recycle code number 3, as well as air fresheners and fragranced products.

The EWG’s Skin Deep database provides an important resource on phthalate-free personal care products.

Despite pressure from consumer advocacy groups, the U.S. Food and Drug Administration has not yet banned phthalates in food packaging.
 

Bisphenol A (BPA)

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

Structurally, BPA acts as an estrogen mimetic and has 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 and bisphenol F) are any safer; they appear to have similar hormonal effects as BPA.

As with phthalates, the majority of ingestion is thought to be food related. BPA has been found in more than 90% of a representative study population in the United States.

Guidance advises avoiding polycarbonate plastics (identifiable with the recycling code number 7), as well as avoiding handling thermal papers such as tickets and receipts, if possible. Food and beverages should be stored in glass or stainless steel. If plastic must be used, opt for polycarbonate- and polyvinyl chloride–free plastics, and food and beverages should never be reheated in plastic containers or wrapping. Canned foods should ideally be avoided, particularly canned tunas and condensed soups. If canned products are bought, they should ideally be BPA free.
 

Dioxins and polychlorinated biphenyls (PCBs)

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

Tetrachlorodibenzodioxin, perhaps the best-known dioxin, is a known carcinogen. Dioxins also have been associated with a host of health implications in development, immunity, and reproductive and endocrine systems. Higher levels of PCB exposure have also been associated with an increased risk for mortality from cardiovascular disease.

Notably, dioxin emissions have been reduced by 90% since the 1980s, and the U.S. Environmental Protection Agency has banned the use of PCBs in industrial manufacturing since 1979. However, environmental dioxins and PCBs still enter the food chain and accumulate in fat.

The best ways to avoid exposures are through limiting meat, fish, and dairy consumption and trimming the skin and fat from meats. The level of dioxins and PCBs found in meat, eggs, fish, and dairy are approximately 5-10 times higher than they are in plant-based foods. Research has shown that farmed salmon is likely to be the most PCB-contaminated protein source in the U.S. diet; however, newer forms of land-based and sustainable aquaculture probably avoid this exposure.
 

Pesticides

The growth of modern monoculture agriculture in the United States over the past century has coincided with a dramatic surge in the use of industrial pesticides. In fact, over 90% of the U.S. population have pesticides in their urine and blood, regardless of where they live. Exposures are thought to be food related.

Approximately 1 billion pounds of pesticides are used annually in the United States, including nearly 300 million pounds of glyphosate, which has been identified as a probable carcinogen by European agencies. The EPA has not yet reached this conclusion, although the matter is currently being litigated.

A large European prospective cohort trial demonstrated a lower risk for cancer in those with a greater frequency of self-reported organic food consumption. In addition to cancer risk, relatively elevated blood levels of a pesticide known as beta-hexachlorocyclohexane (B-HCH) are associated with higher all-cause mortality. Also, exposure to DDE – a metabolite of DDT, a chlorinated 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 these chlorinated pesticides are often fat soluble, they seem to accumulate in animal products. Therefore, people consuming a vegetarian diet have been found to have lower levels of B-HCH. This has led to the recommendation that consumers of produce should favor organic over conventional, if possible. Here too, the EWG provides an important resource to consumers in the form of shopper guides regarding pesticides in produce.
 

Per- and polyfluoroalkyl substances (PFAS)

PFAS are a group of fluorinated compounds discovered in the 1930s. Their chemical composition includes a durable carbon-fluoride bond, giving them a persistence within the environment that has led to their being referred to as “forever chemicals.”

PFAS have been detected in the blood of 98% of Americans, and in the rainwater of locations as far afield as Tibet and Antarctica. Even low levels of exposure have been associated with an increased risk for cancer, liver disease, low birth weight, and hormonal disruption.

The properties of PFAS also make them both durable at very high heat and water repellent. Notoriously, the chemical was used by 3M to make Scotchgard for carpets and fabrics and by Dupont to make Teflon for nonstick coating of pots and pans. Although perfluorooctanoic acid (PFOA) was removed from nonstick cookware in 2013, PFAS – a family of thousands of synthetic compounds – remain common in fast-food packaging, water- and stain-repellent clothing, firefighting foam, and personal care products. PFAS are released into the environment during the breakdown of these consumer and industrial products, as well as from dumping from waste facilities.

Alarmingly, the EWG notes that up to 200 million Americans may be exposed to PFAS in their drinking water. In March 2021, the EPA announced that they will be regulating PFAS in drinking water; however, the regulations have not 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.

To avoid or prevent exposures from PFAS, recommendations include filtering tap water with either reverse osmosis or activated carbon filters, as well as avoiding fast food and carry-out food, if possible, and consumer products labeled as “water resistant,” “stain-resistant,” and “nonstick.”

In a testament to how harmful these chemicals are, the EPA recently revised their lifetime health advisories for PFAS, such as PFOA, to 0.004 parts per trillion, which is more than 10,000 times smaller than the previous limit of 70 parts per trillion. The EPA also has proposed formally designating certain PFAS chemicals as “hazardous substances.”

Dr. Goel, clinical assistant professor of medicine at Weill Cornell Medicine, New York, has disclosed no relevant financial relationships. A version of this article originally appeared on Medscape.com.

If the pandemic served as a window into our health, what it revealed was a U.S. population that is not only sick but also seemingly only getting sicker. Life expectancy is falling precipitously. Three-fourths of Americans are overweight or obese, half have diabetes or prediabetes, and a majority are metabolically unhealthy. Furthermore, the rates of allergic, inflammatory, and autoimmune diseases are rising at rates of 3%-9% per year in the West, far faster than the speed of genetic change in this population.

Of course, diet and lifestyle are major factors behind such trends, but a grossly underappreciated driver in what ails us is the role of environmental toxins and endocrine-disrupting chemicals. In years past, these factors have largely evaded the traditional Western medical establishment; however, mounting evidence now supports their significance in fertility, metabolic health, and cancer.

Although several industrial chemicals and toxins have been identified as carcinogens and have subsequently been regulated, many more remain persistent in the environment and continue to be freely used. It is therefore incumbent upon both the general public and clinicians to be knowledgeable about these exposures. Here, we review some of the most common exposures and the substantial health risks associated with them, along with some general guidance around best practices for how to minimize exposure.
 

Microplastics

“Microplastics” is a term used to describe small fragments or particles of plastic breakdown or microbeads from household or personal care products, measuring less than 5 mm in length.

Plastic waste is accumulating at alarming and devastating proportions – by 2050, it is estimated that by weight, there will be more plastic than fish in the oceans. That translates into 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, plastic exposure has been shown to promote tumorigenesis in animal studies, and in vitro studies have demonstrated the toxicity of microplastics at the cellular level. However, it is not well known whether the plastic itself is toxic or if it simply serves as a carrier for other environmental toxins to bioaccumulate.

According to Tasha Stoiber, a senior scientist at the Environmental Working Group, “Microplastics have been widely detected in fish and seafood, as well as other products like bottled water, beer, honey, and tap water.” The EWG states there are no formal advisories on fish consumption to avoid exposure to microplastics at the moment.

Pressure also is mounting for a ban on microbeads in personal care products.

Until such bans are put in place, it is advised to avoid single-use plastics, favor reusable tote bags for grocery shopping rather than plastic bags, and opt for loose leaf tea or paper tea bags rather than mesh-based alternatives.
 

Phthalates

Phthalates are chemicals used to make plastics soft and durable, as well as to bind fragrances. They are commonly found in household items such as vinyl (for example, flooring, shower curtains) and fragrances, air fresheners, and perfumes.

Phthalates are known hormone-disrupting chemicals, exposure to which has been associated with abnormal sexual and brain development in children, as well as lower levels of testosterone in men. Exposures are thought to occur via inhalation, ingestion, and skin contact; however, fasting studies demonstrate that a majority of exposure is probably food related.

To avoid phthalate exposures, recommendations include avoiding polyvinyl chloride plastics (particularly food containers, plastic wrap, and children’s toys), which are identifiable by the recycle code number 3, as well as air fresheners and fragranced products.

The EWG’s Skin Deep database provides an important resource on phthalate-free personal care products.

Despite pressure from consumer advocacy groups, the U.S. Food and Drug Administration has not yet banned phthalates in food packaging.
 

Bisphenol A (BPA)

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

Structurally, BPA acts as an estrogen mimetic and has 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 and bisphenol F) are any safer; they appear to have similar hormonal effects as BPA.

As with phthalates, the majority of ingestion is thought to be food related. BPA has been found in more than 90% of a representative study population in the United States.

Guidance advises avoiding polycarbonate plastics (identifiable with the recycling code number 7), as well as avoiding handling thermal papers such as tickets and receipts, if possible. Food and beverages should be stored in glass or stainless steel. If plastic must be used, opt for polycarbonate- and polyvinyl chloride–free plastics, and food and beverages should never be reheated in plastic containers or wrapping. Canned foods should ideally be avoided, particularly canned tunas and condensed soups. If canned products are bought, they should ideally be BPA free.
 

Dioxins and polychlorinated biphenyls (PCBs)

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

Tetrachlorodibenzodioxin, perhaps the best-known dioxin, is a known carcinogen. Dioxins also have been associated with a host of health implications in development, immunity, and reproductive and endocrine systems. Higher levels of PCB exposure have also been associated with an increased risk for mortality from cardiovascular disease.

Notably, dioxin emissions have been reduced by 90% since the 1980s, and the U.S. Environmental Protection Agency has banned the use of PCBs in industrial manufacturing since 1979. However, environmental dioxins and PCBs still enter the food chain and accumulate in fat.

The best ways to avoid exposures are through limiting meat, fish, and dairy consumption and trimming the skin and fat from meats. The level of dioxins and PCBs found in meat, eggs, fish, and dairy are approximately 5-10 times higher than they are in plant-based foods. Research has shown that farmed salmon is likely to be the most PCB-contaminated protein source in the U.S. diet; however, newer forms of land-based and sustainable aquaculture probably avoid this exposure.
 

Pesticides

The growth of modern monoculture agriculture in the United States over the past century has coincided with a dramatic surge in the use of industrial pesticides. In fact, over 90% of the U.S. population have pesticides in their urine and blood, regardless of where they live. Exposures are thought to be food related.

Approximately 1 billion pounds of pesticides are used annually in the United States, including nearly 300 million pounds of glyphosate, which has been identified as a probable carcinogen by European agencies. The EPA has not yet reached this conclusion, although the matter is currently being litigated.

A large European prospective cohort trial demonstrated a lower risk for cancer in those with a greater frequency of self-reported organic food consumption. In addition to cancer risk, relatively elevated blood levels of a pesticide known as beta-hexachlorocyclohexane (B-HCH) are associated with higher all-cause mortality. Also, exposure to DDE – a metabolite of DDT, a chlorinated 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 these chlorinated pesticides are often fat soluble, they seem to accumulate in animal products. Therefore, people consuming a vegetarian diet have been found to have lower levels of B-HCH. This has led to the recommendation that consumers of produce should favor organic over conventional, if possible. Here too, the EWG provides an important resource to consumers in the form of shopper guides regarding pesticides in produce.
 

Per- and polyfluoroalkyl substances (PFAS)

PFAS are a group of fluorinated compounds discovered in the 1930s. Their chemical composition includes a durable carbon-fluoride bond, giving them a persistence within the environment that has led to their being referred to as “forever chemicals.”

PFAS have been detected in the blood of 98% of Americans, and in the rainwater of locations as far afield as Tibet and Antarctica. Even low levels of exposure have been associated with an increased risk for cancer, liver disease, low birth weight, and hormonal disruption.

The properties of PFAS also make them both durable at very high heat and water repellent. Notoriously, the chemical was used by 3M to make Scotchgard for carpets and fabrics and by Dupont to make Teflon for nonstick coating of pots and pans. Although perfluorooctanoic acid (PFOA) was removed from nonstick cookware in 2013, PFAS – a family of thousands of synthetic compounds – remain common in fast-food packaging, water- and stain-repellent clothing, firefighting foam, and personal care products. PFAS are released into the environment during the breakdown of these consumer and industrial products, as well as from dumping from waste facilities.

Alarmingly, the EWG notes that up to 200 million Americans may be exposed to PFAS in their drinking water. In March 2021, the EPA announced that they will be regulating PFAS in drinking water; however, the regulations have not 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.

To avoid or prevent exposures from PFAS, recommendations include filtering tap water with either reverse osmosis or activated carbon filters, as well as avoiding fast food and carry-out food, if possible, and consumer products labeled as “water resistant,” “stain-resistant,” and “nonstick.”

In a testament to how harmful these chemicals are, the EPA recently revised their lifetime health advisories for PFAS, such as PFOA, to 0.004 parts per trillion, which is more than 10,000 times smaller than the previous limit of 70 parts per trillion. The EPA also has proposed formally designating certain PFAS chemicals as “hazardous substances.”

Dr. Goel, clinical assistant professor of medicine at Weill Cornell Medicine, New York, has disclosed no relevant financial relationships. A version of this article originally appeared on Medscape.com.

If the pandemic served as a window into our health, what it revealed was a U.S. population that is not only sick but also seemingly only getting sicker. Life expectancy is falling precipitously. Three-fourths of Americans are overweight or obese, half have diabetes or prediabetes, and a majority are metabolically unhealthy. Furthermore, the rates of allergic, inflammatory, and autoimmune diseases are rising at rates of 3%-9% per year in the West, far faster than the speed of genetic change in this population.

Of course, diet and lifestyle are major factors behind such trends, but a grossly underappreciated driver in what ails us is the role of environmental toxins and endocrine-disrupting chemicals. In years past, these factors have largely evaded the traditional Western medical establishment; however, mounting evidence now supports their significance in fertility, metabolic health, and cancer.

Although several industrial chemicals and toxins have been identified as carcinogens and have subsequently been regulated, many more remain persistent in the environment and continue to be freely used. It is therefore incumbent upon both the general public and clinicians to be knowledgeable about these exposures. Here, we review some of the most common exposures and the substantial health risks associated with them, along with some general guidance around best practices for how to minimize exposure.
 

Microplastics

“Microplastics” is a term used to describe small fragments or particles of plastic breakdown or microbeads from household or personal care products, measuring less than 5 mm in length.

Plastic waste is accumulating at alarming and devastating proportions – by 2050, it is estimated that by weight, there will be more plastic than fish in the oceans. That translates into 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, plastic exposure has been shown to promote tumorigenesis in animal studies, and in vitro studies have demonstrated the toxicity of microplastics at the cellular level. However, it is not well known whether the plastic itself is toxic or if it simply serves as a carrier for other environmental toxins to bioaccumulate.

According to Tasha Stoiber, a senior scientist at the Environmental Working Group, “Microplastics have been widely detected in fish and seafood, as well as other products like bottled water, beer, honey, and tap water.” The EWG states there are no formal advisories on fish consumption to avoid exposure to microplastics at the moment.

Pressure also is mounting for a ban on microbeads in personal care products.

Until such bans are put in place, it is advised to avoid single-use plastics, favor reusable tote bags for grocery shopping rather than plastic bags, and opt for loose leaf tea or paper tea bags rather than mesh-based alternatives.
 

Phthalates

Phthalates are chemicals used to make plastics soft and durable, as well as to bind fragrances. They are commonly found in household items such as vinyl (for example, flooring, shower curtains) and fragrances, air fresheners, and perfumes.

Phthalates are known hormone-disrupting chemicals, exposure to which has been associated with abnormal sexual and brain development in children, as well as lower levels of testosterone in men. Exposures are thought to occur via inhalation, ingestion, and skin contact; however, fasting studies demonstrate that a majority of exposure is probably food related.

To avoid phthalate exposures, recommendations include avoiding polyvinyl chloride plastics (particularly food containers, plastic wrap, and children’s toys), which are identifiable by the recycle code number 3, as well as air fresheners and fragranced products.

The EWG’s Skin Deep database provides an important resource on phthalate-free personal care products.

Despite pressure from consumer advocacy groups, the U.S. Food and Drug Administration has not yet banned phthalates in food packaging.
 

Bisphenol A (BPA)

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

Structurally, BPA acts as an estrogen mimetic and has 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 and bisphenol F) are any safer; they appear to have similar hormonal effects as BPA.

As with phthalates, the majority of ingestion is thought to be food related. BPA has been found in more than 90% of a representative study population in the United States.

Guidance advises avoiding polycarbonate plastics (identifiable with the recycling code number 7), as well as avoiding handling thermal papers such as tickets and receipts, if possible. Food and beverages should be stored in glass or stainless steel. If plastic must be used, opt for polycarbonate- and polyvinyl chloride–free plastics, and food and beverages should never be reheated in plastic containers or wrapping. Canned foods should ideally be avoided, particularly canned tunas and condensed soups. If canned products are bought, they should ideally be BPA free.
 

Dioxins and polychlorinated biphenyls (PCBs)

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

Tetrachlorodibenzodioxin, perhaps the best-known dioxin, is a known carcinogen. Dioxins also have been associated with a host of health implications in development, immunity, and reproductive and endocrine systems. Higher levels of PCB exposure have also been associated with an increased risk for mortality from cardiovascular disease.

Notably, dioxin emissions have been reduced by 90% since the 1980s, and the U.S. Environmental Protection Agency has banned the use of PCBs in industrial manufacturing since 1979. However, environmental dioxins and PCBs still enter the food chain and accumulate in fat.

The best ways to avoid exposures are through limiting meat, fish, and dairy consumption and trimming the skin and fat from meats. The level of dioxins and PCBs found in meat, eggs, fish, and dairy are approximately 5-10 times higher than they are in plant-based foods. Research has shown that farmed salmon is likely to be the most PCB-contaminated protein source in the U.S. diet; however, newer forms of land-based and sustainable aquaculture probably avoid this exposure.
 

Pesticides

The growth of modern monoculture agriculture in the United States over the past century has coincided with a dramatic surge in the use of industrial pesticides. In fact, over 90% of the U.S. population have pesticides in their urine and blood, regardless of where they live. Exposures are thought to be food related.

Approximately 1 billion pounds of pesticides are used annually in the United States, including nearly 300 million pounds of glyphosate, which has been identified as a probable carcinogen by European agencies. The EPA has not yet reached this conclusion, although the matter is currently being litigated.

A large European prospective cohort trial demonstrated a lower risk for cancer in those with a greater frequency of self-reported organic food consumption. In addition to cancer risk, relatively elevated blood levels of a pesticide known as beta-hexachlorocyclohexane (B-HCH) are associated with higher all-cause mortality. Also, exposure to DDE – a metabolite of DDT, a chlorinated 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 these chlorinated pesticides are often fat soluble, they seem to accumulate in animal products. Therefore, people consuming a vegetarian diet have been found to have lower levels of B-HCH. This has led to the recommendation that consumers of produce should favor organic over conventional, if possible. Here too, the EWG provides an important resource to consumers in the form of shopper guides regarding pesticides in produce.
 

Per- and polyfluoroalkyl substances (PFAS)

PFAS are a group of fluorinated compounds discovered in the 1930s. Their chemical composition includes a durable carbon-fluoride bond, giving them a persistence within the environment that has led to their being referred to as “forever chemicals.”

PFAS have been detected in the blood of 98% of Americans, and in the rainwater of locations as far afield as Tibet and Antarctica. Even low levels of exposure have been associated with an increased risk for cancer, liver disease, low birth weight, and hormonal disruption.

The properties of PFAS also make them both durable at very high heat and water repellent. Notoriously, the chemical was used by 3M to make Scotchgard for carpets and fabrics and by Dupont to make Teflon for nonstick coating of pots and pans. Although perfluorooctanoic acid (PFOA) was removed from nonstick cookware in 2013, PFAS – a family of thousands of synthetic compounds – remain common in fast-food packaging, water- and stain-repellent clothing, firefighting foam, and personal care products. PFAS are released into the environment during the breakdown of these consumer and industrial products, as well as from dumping from waste facilities.

Alarmingly, the EWG notes that up to 200 million Americans may be exposed to PFAS in their drinking water. In March 2021, the EPA announced that they will be regulating PFAS in drinking water; however, the regulations have not 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.

To avoid or prevent exposures from PFAS, recommendations include filtering tap water with either reverse osmosis or activated carbon filters, as well as avoiding fast food and carry-out food, if possible, and consumer products labeled as “water resistant,” “stain-resistant,” and “nonstick.”

In a testament to how harmful these chemicals are, the EPA recently revised their lifetime health advisories for PFAS, such as PFOA, to 0.004 parts per trillion, which is more than 10,000 times smaller than the previous limit of 70 parts per trillion. The EPA also has proposed formally designating certain PFAS chemicals as “hazardous substances.”

Dr. Goel, clinical assistant professor of medicine at Weill Cornell Medicine, New York, has disclosed no relevant financial relationships. A version of this article originally appeared on Medscape.com.