Dr. Victor S. Sierpina
By now, you have heard about probiotics, the healthy bacteria in our system that help maintain our health. This six pound mass of microscopic organisms are essential to digestion as they help us break down cellulose and other plant and animal matter that our bodies’ can’t digest on their own.
One surprising area of the impact of bacteria and the microbiome that has been recently discovered are the effects of gut bacteria on the brain and on behavior.
Dr. Mark Lyte faced strong headwinds in the research community when he proposed that gut bacteria could affect our moods. Though he was one of the first to advocate the concept of “psychobiotics,” he still advises caution in rushing to overly broad conclusions and therapies until more science is done in the area.
A recent New York Times Magazine synopsized several recent studies done primarily on mice found correlations between their gut bacteria and behavior such as markers of anxiety. Mice are not men but the physiology suggested by these studies was fascinating.
Stressed mice whose gut was infused with certain probiotics acted more relaxed compared to those with usual gut bacterial profiles. They behaved “as if they were on Prozac” according to the researcher, Dr. John Cryan.
Did you ever have a “gut feeling” about something? This is just a simple reflection on how our gut contains so many psychoactive chemicals that affect our moods and behavior.
Serotonin, which is the neurotransmitter involved in treatment of depression, anxiety, and other psychiatric conditions, is found in very high levels in our gut. It can be affected by how we eat, our stress levels, and now it appears by the array of bacteria in our gut. Another gut neurotransmitter is gamma-aminobutyric acid (GABA) which is affected by drugs like Valium and Xanax.
If a primary actor in our gut is our microbiome, it isn’t a great stretch to see how their metabolic activity including neurotransmitter release may have a significant effect on our brains, mood, and behavior.
It turns out we can affect the kinds and numbers of various bacteria in our gut.
1) Eat more PREbiotics. These are largely plant-based fibers and carbohydrates that cannot be digested by the human body. they are food for PRObiotics. Prebiotics include foods like whole grains, bananas, onions, garlic, honey, and artichokes
2) A plant based diet, in general, fosters healthier species of gut probiotics
3) It turns out that being vaginally birthed and breast fed improves the healthy profile of gut bacteria in children
4) Eating probiotics like yogurt or other fermented foods should be a regular part of our diet
5) Replace our gut bacteria with healthy probiotics after they have been altered by antibiotics, chemotherapy, steroids, and other medical interventions. Probiotic supplements can be useful here.
Could altering our gut bacteria replace some of our psychiatric drugs? Are some psychological conditions brain problems or gut problems? Studies on the microbiome for anxiety, depression, autism, ADHD, and even schizophrenia are showing promise.
While much of this research is still preliminary, I predict that the studies of probiotics and their role as psychobiotics will eventually have as big an impact on human health as the discovery of antibiotics.
Dr. Victor S. Sierpina is the WD and Laura Nell Nicholson Family Professor of Integrative Medicine and Professor of Family Medicine at UTMB.