RESEARCH--Exercise Improves Gut Bacteria

Many studies show that exercise helps to prevent heart attacks, and it may do so by changing the bacteria in your colon. A recent study from Finland shows that exercising for just six weeks, without any additional change in diet or lifestyle, can increase healthful anti-inflammatory bacteria (Akkermansia) and reduce harmful inflammation-promoting Proteobacteria in your colon (Front Microbiol, October 3, 2018).

In this study, 17 sedentary and overweight women started a heart-rate-regulated exercise program on stationary bicycles for three training sessions per week. After six weeks, stool cultures showed healthful colon bacteria changes, even though the subjects did not lose any weight. There was also a significant reduction in phospholipids and cholesterol in VLDL cholesterol, which is believed to help prevent heart attacks because VLDL cholesterol is converted into the harmful LDL cholesterol that helps to form plaques in your arteries. Exercise also decreased Vascular Adhesion Protein-1, a measure of inflammation that causes plaques to form in arteries and break off to cause heart attacks.

Exercise Promotes Good Gut Bacteria
Two previous studies, one in
humans and one in mice, also show that exercise alone leads to beneficial changes of colon bacteria. In the human study, researchers had 18 lean and 14 obese subjects exercise for 30 to 60 minutes, three days per week for six weeks (Med & Sci in Sports & Ex, Nov 11, 2017). Then they were told not to exercise for six weeks. All subjects were told not to change their diets.

After the six weeks of exercise, all of the subjects, both obese and lean, had an increase in the good colon bacteria that make short chain fatty acids (butyrate) and suppress inflammation. The lean subjects had the greatest increase in the good bacteria after exercising and the obese subjects had a more modest increase in the good bacteria. When the same subjects were checked after six weeks of not exercising, all had a marked reduction of these good colon bacteria. This study shows that exercise appears to increase the number of good colon bacteria without any dietary change whatever, that lean people have a greater increase than obese people, and that the potential benefit does not last if exercise is stopped.

In the mouse study, researchers took fecal material from groups of exercising mice and non-exercising mice and transplanted it into the colons of bacteria-free mice (Gut Microbes, published online Sep 1, 2017). The bacteria-free mice developed the same types of colon bacteria that they received from each donor group. Fecal samples taken from exercising mice gave the recipient mice much higher levels of the beneficial bacteria that produce high levels of short chain fatty acids (butyrate) that are anti-inflammatory and help to lower cholesterol. Then the researchers gave the recipient mice chemicals that cause inflammation, which damaged their colons to cause colitis. The mice that had received bacteria from the exercising mice had far less inflammation, far less colon damage and much quicker recovery times than the mice who had received bacteria from the sedentary mice.

Importance of Colon Bacteria
More than 100 trillion microorganisms live in your body (FEMS Microbiol Rev, 2014;38:996-1047), which means that only about ten percent of the total number of cells in your body are human cells, while the rest are symbiotic bacterial cells (Nature, Jun 17, 2010;465(7300):879-80). Over the last few years, a very large number of studies have increased our understanding of the many functions of gut bacteria. For example, see:

My Recommendations
These recent experiments provide yet another reason for exercising every day: exercise, by itself, encourages the growth of good colon bacteria that reduce inflammation, keep the gut healthy and reduce your chances of suffering a heart attack, stroke, diabetes, certain cancers and autoimmune diseases.

Many of my recent reports explain how your diet influences the balance of good and bad bacteria in your colon, so I continue to recommend a high-plant diet that includes a wide variety of vegetables, fruits, beans, whole grains, nuts and any other edible plant parts. Among their many benefits, plants help to prevent diseases and prolong lives by increasing colonic bacterial production of SCFAs (short chain fatty acids) that reduce inflammation.
Dr. Mirkin is a lifelong runner and cyclist. A graduate of Harvard University and Baylor University College of Medicine, he has written many widely-read sportsmedicine books, and has generously granted us use of excerpts from his outstanding website,