Two recent studies have shown the first evidence that exercise on its own can change our microbe composition. One study involved mice, while the other involved humans. Both studies isolated exercise-induced changes from other factors that could affect the microbiota. The full story can be found at Science Daily, but here are bullets of the article:
- In one study, scientists transplanted fecal material from exercised and sedentary mice into the colons of sedentary mice with no microbiota of their own.
- In the other study, the team tracked changes in the composition of gut microbiota in human participants as they transitioned from a sedentary lifestyle to a more active one, and back again.
- Both studies were conducted at the University of Illinois, while the mouse study involved scientists at the Mayo Clinic in Rochester, Minnesota.
- Recipients of the exercised mouse microbiota had more microbes that produce butyrate, a short-chain fatty acid that promotes healthy intestinal cells, reduces inflammation and generates energy for the host.
- They also appeared to be more resistant to inflammatory bowel disease.
- In the human study, the team recruited 18 lean and 14 obese sedentary adults, sampled their gut microbiomes, and started them on an exercise program during which they performed supervised cardiovascular exercise for 30-60 minutes three times a week for six weeks.
- The researchers sampled participants’ gut microbiomes again at the end of the exercise program and after another six weeks of sedentary behavior.
- Participants maintained their usual diets throughout the course of the study.
- Fecal concentrations of SCFAs, in particular butyrate, went up in the human gut as a result of exercise. These levels declined again after the participants reverted to a sedentary lifestyle.
- The most dramatic increases were seen in lean participants, who had significantly lower levels of SCFA-producing microbes in their guts to begin with.
- Obese participants saw only modest increases in the proportion of SCFA-producing microbes.
There’s much more work to be done in studying how exercise affects the human microbiome, and why we see different changes in lean versus obese adults. That said, this study proves that exercise, independent of food, has a definitive impact on the health and prosperity of the human microbiome.