Our gut covers a large surface area that is in direct contact with potential pathogens at all times. It contains about 70% of our immune cells and plays essential roles in the development and function of our immune system.

Strenuous endurance sports reduce the blood flow, oxygen, and nutrients in the gut while increasing permeability of the gastrointestinal epithelial wall and the destruction of gut mucous thickness (sometimes called “leaky gut”). Leaky gut increases endotoxicity, in which pathogens or endotoxins are able to cross the intestinal barrier into the bloodstream, causing a disruption of the immune system and stimulating excess inflammatory immune response.

Reduced blood flow to the gut can occur within ten minutes of strenuous, high-intensity exercise. One hour after a long-distance triathlon event, 68% of athletes were found to have endotoxemia.

A healthy gut and balanced gut microbiome protect us against leaky gut. To counteract the excess inflammatory responses brought on by intense exercise, our gut microbiome and its short-chain fatty acid (SCFA) metabolites can reduce mucosa permeability in the gut and inhibit inflammatory cytokines.

Gut microbial-derived SCFAs can activate signals for gene expressions to influence immune cell differentiation and reinforce the anti-inflammatory properties of dendritic cells to attenuate inflammation in the gut. These anti-inflammatory effects reduce the risk of exercise-induced gut symptoms and delay fatigue symptoms in endurance performances.

On the other hand, the pro-inflammatory compound lipopolysaccharide (LPS), is also gut microbial-derived and can increase gut permeability. Increased LPS levels, known as metabolic endotoxemia, triggers chronic low-grade inflammation and is a major driver of metabolic diseases.

Maintaining a balanced, healthy gut microbiome is therefore key to maintaining healthy metabolism and preventing excess or chronic inflammation.

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