Somewhere In Between: Leaky Gut

As an MD and fellowship-trained Integrative Physician, I am often asked about “health conditions” that are not recognized by the medical community and do not qualify as medical diagnoses for a number of reasons: (a) there may be an evolving theory that has not been thoroughly researched, and/or (b) there may be an oversimplified physiologic process or finding that, while having some science, lacks consistent connections to the disease process or outcomes. Some theories, when fully investigated, may in time come to be recognized while others will not–the scientific method is a lengthy process. When approached with these “conditions,” I often find myself “somewhere in between” and I continually pour over new research outcomes in an effort to treat patients who are feeling unwell. While I am sympathetic to those who are frustrated with the pace of medicine and the lack of answers pertaining to their health, we must remember that little truths that are strung together produce interesting headlines, but do not make for sound medical practices. This is the first in a three-part series.  

“Leaky Gut”

We often read about “leaky gut” and “leaky gut syndrome,” but we need to think sensibly about how this described physiologic process quickly transformed from a physiologic finding to a syndrome that is continuously linked with a lengthy list of disorders. The intestinal barrier is extremely complex and is poorly–often wrongly–depicted in many articles that are directed at the general public and health enthusiasts, often by holistic, alternative practitioners, many of whom have made a career out of treating “leaky gut.” However, while there is no data thus far to support “leaky gut syndrome,” changes in permeability and barrier function do exist and have been found to be correlated with a number of diseases. A quick search of PubMed shows us that there are many ongoing clinical trials looking into the gastrointestinal barrier function, the microbiome and permeability changes, and there has, in fact, been exciting research in this field. Much of the research is still early and much of what has been discovered is largely based on bench research and animal studies. Physicians like to see more human studies, validated ways to measure, and treatment that provides meaningful and measurable outcomes. 

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Photo by Artem Podrez from Pexels

What We Do Know  

  • The intestinal barrier is complex and dynamic, is certainly more than the often touted “one cell layer,” and we are still early in our understanding of it.
  • Only extremely small molecules “leak” and this is not directly into the bloodstream – not actually whole bacteria and food commonly implied in lay articles.
  • Changes in permeability have been found in those with certain diseases but have also been noted in healthy people and at different times in the lifespan.

What We Don’t Know

  • Are changes in barrier function and permeability the cause or effect of diseases with which they are correlated? 
  •  What changes in intestinal permeability might be considered normal and even beneficial ?
  • Does it make sense to test for intestinal permeability and barrier dysfunction? And does this have an impact on disease outcome? (Currently there are no consistent reliable tests for public use, as most of the testing is aimed at research.)
  • Can we repair or treat damage to the intestinal barrier and, if so, does this provide significant benefits to disease prevention, development and management?

What We Can Do

Manage stress

Our GI tracts are sensitive to stress and I often wonder if “gut reactions” are emotions felt by the nervous system in our guts. Research on the impact of stress on the GI tract has been evolving for decades, and there are a few books that I recommend on this subject:

The Second Brain: A Groundbreaking New Understanding Of Nervous Disorders Of The Stomach And Intestine by Michael Gershon

 Why Zebras Don’t Get Ulcers by Robert Sapolsky 

The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health by Emeran Mayer.

Work on Diet and Lifestyle

  • Eat at least the minimum amount of recommended dietary fiber. This is currently believed to be essential for maintenance of the very important mucus layer in the gastrointestinal tract and is also associated with production of beneficial short chain fatty acids. Check out the work of Erica and Justin Sonnenburg, PhDs, leading researchers in the intestinal microbiome field. Their book is an outstanding resource. 
  • Adopt a diet that is mostly plants and limit saturated fats, as they have been demonstrated to cause inflammation in the gastrointestinal tract.
  • Keep sugar intake to a minimum and avoid emulsifiers (additives that appear in processed foods such as mayonnaise, ice cream and baked goods to create a smooth texture and prevent separation). There is emerging evidence that these may be damaging to the mucus layer. 
  • Drink alcohol only in moderation and maintain a healthy weight. 
  • Keep non-steroidal, anti-inflammatory drugs (such as Ibuprofen) to a minimum and avoid unnecessary antibiotics.
  • Maintain a common sense approach until we know more.

Lastly, please avoid or use caution with: 

  • Gut repair protocols (glutamate, bone broth, zinc, etc.). Most are based on cellular, bench and animal research and have not proved to impact barrier function in human clinical trials.
  • Testing for “leaky gut” and food sensitivity. Current testing on the market remains inconsistent with little clinical value.
  • Microbiome analysis. An optimal or healthy microbiome has not yet been well defined, nor do we really know how well we can change it. Projects such as the American Gut Project are helping us learn what “normal” and “healthy” microbiomes look like, as currently there is not a consensus.
  • Prolonged restrictive diets in the hopes to fix “leaky gut” and autoimmune disorders. In the long run these can lead to malnutrition and, in some cases, eating disorders. Better options would be short trials (4-6 weeks) of an elimination diet or even a low FODMAP diet, with reintroductions (adding food back) under the supervision of a medical provider. 

It’s important to keep in mind that although intestinal permeability changes are increasingly showing up in medical literature, we must have patience with the scientific process. Please consult with your physician before giving credence to methods and therapies that are overarching and jump to overrated conclusions which, unfortunately, are commonplace. 

Worth Reading

Ahmad, R., Batra, S.K., Dhawan, P., et al., Gut permeability and mucosal inflammation: bad, good or context dependent, Mucosal Immunology/2017

Barbara, Giovanni, Bischoff, Stephan C., Buurman, Wim, et al., Intestinal permeability – a new target for disease prevention and therapy, BMC Gastroenterol/2014

Bowen, Richard, The Gastrointestinal Barrier, VIVO Pathophysiology/2018

Odenwald, Matthew A., Debunking the Myth of ‘Leaky Gut Syndrome,’

Odenwald, Matthew A., Turner, Jerrold R., Intestinal Permeability Defects: Is It Time to Treat?,