About Functional GI Disorders, Microbes, and Brain-Gut Interactions

This article was adapted from an interview conducted with Emeran Mayer Professor of Medicine at UCLA at the 2016 Gut Microbiota for Health World Summit

There are many exciting developments and discoveries being made about the connection between our gut (digestive system) and our brain and how it affects our health, as well as how vital our gut microbiota are. 

Gut microbiota helps with digestion, maintaining the immune system, and protecting pathogens.  When disturbed, our bodies may start developing symptoms; for example, taking antibiotics can lead to diarrhea. 

The Brain and the gut talk to each other

A connection occurs between what gut microbes produce and brain activity, function and structure.  This connection begins during fetal developement and is established by about three years of age.  If there is an imbalance of bacteria in our gut, a person can be vulnerable to developing a functional gastrointestinal (GI) disorder. 

Diets can affect types of metabolites gut microbes make.  These microbial metabolites may influence the nervous system in the gut (the enteric nervous system) and the brain. Diet becomes an essential factor, not only for its direct effect on health, but also for what it does to the microbes, what they produce, and how these metabolites affect the nervous system. 

Microbial metabolites are substances produced by gut microbes by fermenting food that the human GI system cannot  process or absorb. Hundreds of thousands of these metabolites are made in the gut.

The Low FODMAP diet and IBS

FODMAPs are types of carbohydrates found in foods like wheat and beans.  Followers of the low FODMAP diet eat less of the fiber that supports beneficial microbes in the gut.  In the short term, a diet like this can lesson symptoms for some IBS patients.  Still, these diets can be difficult to maintain for a long time, and may have adverse side effects on your gut microbiota.  Moreover, it appears that a healthy, balanced microbiota can alleviate symptoms. Som a low FODMAP diet may not be the best choice for managing IBS. 

Learn more about the low FODMAP Diet and the affects on the gut

Mediterranean style diet

Eating a mix of complex carbohydrates, protein, and fats is essential to growing healthy gut microbes. The Mediterranean diet or similar diets probably come closest to this, with a high proportion of complex carbohydrates from plant-based foods, minimal animal fat, a relatively small amount of protein mainly from fish and chicken, and few refined sugars.

Stress can affect the GI tract

We know that feeling anxious or sad while eating can affect how the gut contracts or secretes enzymes to digest food.  In addition, we know that stress can affect the behavior of the gut microbiota directly.  An an acutely stressed person or one chronically affected by sad emotions will have a different set of microbes. It seems that a balanced mind and a proper diet go hand in hand.  If a person is constantly feeling stressed, even if they incorporate a healthy diet, will not gain the same benefits as a less stressed person. 

Gut Microbes helps maintain a balance between the brain and the gut

A person can take care of what, when, and how they eat to promote healthy balance in the gut microbiome. Maintaining a positive emotional state and, as much as possible, relaxing, and enjoying mealtime will help support the gut microbes. Many simple forms of stress reduction, such as exercise, abdominal breathing, or progressive muscle relaxation, can reduce pain. Eating a sensible diet, reducing stress, and working toward a balanced body and mind are steps to improving well-being.

Emeran Mayer, MD and Cole Norton
Emeran Mayer, MD and Cole Norton

*The 2016 Gut Microbiota for Health World Summit, organized by the American Gastroenterological Association (AGA) and the European Society of Neurogastroenterology & Motility (ESNM), took place in Miami, FL from March 5–6, 2016.

Emeran Mayer, MD is Professor of Medicine and Executive Director of the G. Oppenheimer Center for Neurobiology of Stress and Resilience at UCLA in Los Angeles, CA. Dr. Mayer is a member of the Board of Directors of IFFGD. His book, The Mind-Gut Connetion: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choice, and Our Overall Health, is available at Amazon.


Adapted from IFFGD Publication #273 “Functional GI Disorders, Microbes, and Brain-Gut Interactions” by Cole W. Norton and Aki S. Norton, IFFGD, in collaboration with Emeran Mayer Adapted by Abigale Miller. 

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