Exercise and the Gut Microbiome

Have you ever been curious to know how exercise might affect your gut? Specifically how it affects the gut microbiome?

It has been well established that the development of the gut microbiome begins at birth and develops over life- with influences such as diet and medication/antibiotic use shaping the gut microbiome.  

A recent review by Mailing et al. looked at studies regarding exercise and gut microbiome (Exerc Sport Sci Rev., 2019). They specifically wanted to address if exercise independently affected the gut microbiome, what mechanisms impact this, and the implications for the gut. They also looked at how exercise affected the gut microbiome in states of disease.

They noted that animal studies suggest exercise training independently alters the composition and functional capacity of the gut microbiome- more specifically, butyrate (a short-chain fatty acid) that is produced from the fermentation of dietary fiber which acts as food for intestinal cells, increases cell growth, promotes a strong gut and can improve immunity.

In human studies, exercise was found to have a mixed impact on the gut microbiome. Some studies suggest exercise increases the firmicutes to bacteroidetes ratio while others suggest it decreases or does not change. Other studies suggest that changes in the gut microbiome are transient meaning it changes during periods of exercise and then does not change or have a positive impact during periods of a sedentary lifestyle. 

There may be other confounding factors affecting how exercise might influence the gut: type and duration of exercise, the BMI status of the person exercising as well as their diet. More research is needed to figure out these questions. However, collectively, research has overall shown a positive benefit of exercise on the gut microbiome thus improving human health.

Potential mechanisms where exercise might impact the gut:

• Altered gene expression of immune cells leading to less inflammation by the production of antimicrobial properties that lead to stability between the body and the gut microbiome
• Improved integrity of the gut mucous layer- preventing bacterial translocation or bacterial infections in the bloodstream
• Long-term resilience of the gut barrier through regular exercise, improving the immune system
• Improved vagal tone - impacting GI motility/transit (how fast nutrients move through the GI tract)
• Impact on bile acid regulation- low bile acid secretion is linked to gut dysbiosis and significant change in the gut microbiome
• Altered metabolic flux or how fast molecules are metabolized - myokines, metabolites, and neuroendocrine hormones are released from muscle during exercise and all interact with the gut through the immune system- this can impact the gut environment thus impacting the microbiome

Overall, exercise seems beneficial in regards to how it influences the gut. It could help decrease IBS symptoms, improve bowel habits and increase your immune system. There is also research that suggests exercise affects the gut via the brain (exercise reduces stress/anxiety) which could lead to a more healthy variety of microbes in the gut.

So what do you do next?

If you love exercising, keep doing it regularly. If you would like to start exercising make sure to talk with your doctor to make sure it is appropriate for you. Start with some realistic goals (i.e. walking the dog for 30 minutes 3 times a week), find something you enjoy/try something new. 

Your gut microbiome will appreciate it!

Try this easy 9-minute workout!

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