Exercise has a beneficial effect on the health of your gut microbiome.

Recent research shows that exercise and physical activity increase the numbers and types of good bacteria that live in the gut, and decrease harmful bacteria.

The gut microbiome is the trillions of microbes (bacteria, viruses, fungi) that live in our intestines. This microbial community plays an important role in proper immune system function, for getting nutrients from foods, protecting us from harmful microbes (pathogens), and for metabolic health. Some bacterial species living in the gut are associated with good health (health-promoting), while certain other bacteria species are associated with inflammation and diseases, such as heart disease and diabetes.

Exercise and a Good Diet Go Hand in Hand

It is wonderful that exercise is another way one can improve the gut microbiome besides eating a good diet. In fact, the two go hand in hand, with exercise and diet interacting and promoting a healthy microbiome.

It has only been in the last decade, with the development of modern methods such as genetic sequencing, that researchers could finally see the hundreds of different microbial species living in the gut. Only now could they study the gut bacteria of people living different lifestyles.

Comparing the Gut Microbiome - Athletes vs Nonathletes

In 2014, the first study looking at the effects of exercise on gut bacteria compared professional rugby players to nonathletes. Researchers from the University College Cork found that the athletes had more diversity (variety of species) in the gut microbiome – which is considered a sign of health, and that their levels of inflammation (as measured by inflammatory markers) were lower than in nonathletes. The main conclusion was that exercise increases gut bacterial diversity in humans, especially of beneficial bacteria such as Akkermansia muciniphila. They also concluded that the combination of exercise and diet (especially the high protein diet of athletes) has a beneficial impact on the gut bacteria.

What about the gut microbiome of ordinary people who exercised every week compared to nonactive couch potato types?

More importantly, could someone change and improve their personal gut microbiome by exercising?

Researchers started comparing the gut bacteria of different groups of ordinary people. They found differences in the types and numbers of bacteria among physically active persons compared to those who led a non-active (sedentary) lifestyle. Exercisers had a healthier gut microbiome, with more types and numbers of beneficial bacteria, and nonactive persons had more bacteria species linked to poor health and diseases. Active persons tended to eat more fruits, vegetables, and fiber than sedentary persons, but studies in both humans and animals confirmed that exercise alone also alters gut bacteria.

Health Promoting Beneficial Bacteria

A study by Dr.Bressa and colleagues found differences in gut bacteria between active women (they exercised at least 3 hours per week) and those that were not active. They found that the active women had more of the health promoting beneficial bacteria such as Faecalibacterium prausnitzii, Roseburia hominis, and Akkermansia muciniphila than the sedentary women. The sedentary women also had some bacterial species not seen in the active women. The researchers said that exercise "modifies the composition of gut microbiota" (the pattern of gut microbes) in a way beneficial for health.

Other studies actually followed people over time as they exercised and looked at their gut bacteria changes. They confirmed that exercise alters gut bacterial communities in a good way, and that the longer the exercise or physical activity goes on, the bigger the changes. When people exercise for at least 6 to 8 weeks, there is an increase in the variety or diversity of bacterial species (which is good), more beneficial bacterial species, as well as increased cardiovascular fitness.

Positive Changes in the Composition of Gut Bacteria That Produce Butyrate

University of Illinois researchers found that in both mice and humans, exercise programs lasting for weeks (3 times per week for 6 weeks in humans) resulted in positive changes in the composition of gut bacteria, including bacteria that produce butyrate. Butyrate is a short-chain fatty acid that promotes healthy intestinal cells, reduces inflammation, and generates energy for the host. The changes in gut bacteria from exercise was bigger in lean persons than in obese persons. However, 6 weeks after stopping exercising and going back to a sedentary (non-active) lifestyle, the positive changes had disappeared.

By the way, all the good bacteria species (e.g. Faecalibacterium prausnitzii, Roseburia hominis, and Akkermansia muciniphila) that increase from exercise and being physically active, as well as from a good diet high in fiber, are not available in probiotics that one can buy.

What is the minimal amount of exercise that results in beneficial changes?

The minimum exercise that health organization guidelines recommend for health benefits is at least 2 1/2 hours (or 150 minutes) a week. But all guidelines stress that some exercise is better than none.

The Physical Activity Guidelines (PAG) from the American Heart Association recommends that adults do at least 150 to 300 minutes of moderate-intensity aerobic physical activity a week, or 75 to 150 minutes of vigorous-intensity activity, or an equivalent combination of moderate- and vigorous-intensity activity.

What counts as exercise?

Exercise generally means any physical activity that gets the heart rate up. It can be exercises at home or in an exercise class, in a gym using equipment, or it can mean any physical activity that gets you moving for a minimum of 10 minutes at a stretch.

Brisk walking is a great moderate-intensity exercise, as is gardening, relaxed bicycling, playing tennis, and active chores around the home. Vigorous intensity exercise examples are hiking uphill, swimming laps, running, heavy yardwork, jumping rope, and shoveling snow.

But remember - you have to continue with the exercises and physical activity or beneficial gut bacteria changes will disappear. So get active and move, move, move!