Gastrointestinal complaints such as nausea, cramps, vomiting, and diarrhea are common among athletes. This is thought to be due to the change in blood flow during intense exercise—blood is diverted from digestion to the heart and muscles where it is needed. The decrease in blood flow to the intestines during intense exercise is known to increase intestinal permeability, or leaky gut. This, in turn, can lead to increased susceptibility to infection or autoimmune disease.

A recent study published in the Journal of the International Society of Sports Nutrition tried to address this increased leaky gut by using a multi-strain probiotic formula in people undergoing intense exercise. Twenty-three trained men, average age 38 were given either 10 billion cultures of a six-strain probiotic formula (two Bifidobacterium and Lactobacillus strains and one Enterococcus and Lactococcus strain) or placebo daily for 14 weeks.

The researchers tested levels of inflammation, protein oxidation, oxidative stress, and leaky gut. In those people taking the probiotic, they found decreased inflammation and protein oxidation, as well as a decrease in Zonulin, a marker of leaky gut when compared to those taking the placebo. “These results demonstrate promising benefits for probiotic use in trained men,” stated the authors, “Our data support the hypothesis that an adequate probiotic supplementation can improve intestinal barrier function, redox hemostasis, and low-grade inflammation in men under sustained exercise stress.”

This study builds on previous studies that have found probiotics to help reduce respiratory tract infections in sports and exercise, and to shorten the duration of digestive symptoms in trained athletes. Probiotics have also been found to decrease inflammation and increase antioxidant levels after exercise. Athletes are yet one more group of people who are discovering that digestive health is the foundation of total-body health.