Evidence that Exercise Increases Good Gut Bacteria

Tips for Staying Active in Winter Months

By Ross Pelton, RPh, PhD, CCN
Scientific Director, Essential Formulas

There is increasing evidence that regular exercise promotes the growth of beneficial bacteria in the colon. This is important because over 99.9% of the probiotic bacteria in the human gut microbiome reside in the colon’s anaerobic (non-oxygen) environment. This is where most of your all-important postbiotic metabolites are created when your probiotic bacteria ferment the fibers and polyphenols in your foods.

An increasing body of scientific evidence indicates that postbiotic metabolites function in multiple ways to promote and regulate your health. Conversely, poor diet and lifestyle factors encourage the growth of harmful bacteria in the microbiome, increasing the risk of heart attacks, strokes, diabetes, autoimmune diseases, and colon cancer.

Two new studies, one in mice and one in humans, report that exercise promotes the growth of beneficial bacteria in your colon and reduces the number of bad ones.

Exercise & Gut Bacteria in Mice

Researchers transplanted material from a group of exercising and sedentary mice into the colons of germ-free mice (mice with no bacteria in their gastrointestinal tract). The germ-free mice developed the same species of colon bacteria that they received from each donor group. Recipient mice that received fecal samples from the exercising mice developed much higher levels of beneficial bacteria that produce high levels of short-chain fatty acids, known to provide anti-inflammatory activity and help reduce cholesterol levels.i

The recipient mice were then given a chemical that causes inflammation, damages their colons, and causes colitis. Mice that received bacteria from the exercising mice had far less inflammation, far less damage to cells lining the colon, and exhibited much faster recovery times than those who had received bacteria from the sedentary mice.

Exercise & Gut Bacteria in Humans

Investigators monitored 18 lean and 14 obese female subjects in a supervised, endurance-based exercise program for 30 to 60 minutes, three days/week for six weeks. They were then instructed not to exercise for six weeks. After six weeks of exercise, both the lean and obese subjects increased the number of beneficial colon bacteria that produce short-chain fatty acids known to suppress inflammation.

The lean subjects had the most significant increase in good bacteria after exercising, while the obese subjects had a more modest increase. Also, it was revealed that the exercise-induced changes in the microbiota were reversed once exercise training was discontinued.ii

These studies add to the body of scientific studies that indicate that regular exercise is a vital lifestyle factor contributing to maintaining a healthy microbiome.

i Allen JM. The effects of exercise training on the gut microbiota, microbial metabolites, and microbial-host interactions in mice and humans. 2017. https://www.ideals.illinois.edu/handle/2142/97726
ii Allen JM, et al. Exercise Alters Gut Microbiota Composition and Function in Lean and Obese Humans. Med Sci Sports Exerc. 2018 Apr;50(4):747-757.