Evidence suggests that physical exercise may help support certain aspects of the gut microbiome. Physical exercise has been shown in studies to help promote microbial diversity and the proliferation of some microbes that may help support certain aspects of mucosal immunity. It has also been shown to help support a healthy Bacteroidetes-Firmicutes ratio. It is suggested through research that the gut microbiome may, in turn, also help support certain aspects of athletic performance and the body’s response to high-intensity exercise. 

A recently published systematic review by Di Dio and colleagues explored the potential efficacy of probiotic administration on certain aspects of athletic performance. There were 13 studies included in this review, and the majority were double-blind, placebo-controlled trials. Another 7 of the included studies focused on endurance athletes. High-intensity exercise has been reported to potentially decrease the function of certain immune cells and temporarily increase the burden of oxidative stress, along with a potential increase in intestinal permeability. Di Dio and colleagues suggest that probiotic administration may help support these changes due to strenuous exercise.

One placebo-controlled clinical study involved supplementation with 30 billion colony-forming units (CFUs) of Lactobacillus plantarum PS128 twice daily for 4 weeks in triathletes. Improvements in endurance running performance were observed in the treatment group as compared with the placebo group.

Another study involving supplementation with L. plantarum PS128 in triathletes reported improvements in biomarkers related to antioxidative status after a triathlon. The treatment group also experienced decreases in certain pro-inflammatory cytokines, including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-8. Increases in IL-10, a cytokine associated with anti-inflammatory characteristics, was also observed after intense exercise in the L. plantarum group.

A clinical study in elite rugby players involved supplementation with 60 billion CFUs of a blend of Lactobacilli, Bifidobacterium, and Streptococcus daily for 17 weeks. Muscle soreness and leg heaviness were shown to be lower in the treatment group when compared to a placebo. Improvements in salivary C-reactive protein and sleep quality were also observed in the treatment group.

Another randomized, placebo-controlled study included in the review by Di Dio and colleagues reported improvements in the aerobic capacity of athletes in the presence of 30 billion CFUs of Lactobacillus casei daily for 6 weeks. Significant increases in ”‘run time to fatigue” measurements were observed in a 4-week-long study involving runners who received 45 billion CFUs of a combination of L. acidophilus, L. rhamnosus, L. casei, L. plantarum, B. lactis, B. Bifidum, and S. thermophilus. Increases in maximum oxygen uptake VO₂max and exercise capacity were observed in a 3 month-long study involving long-distance runners who received a probiotic supplement containing B. lactis, L. brevis, L. lactis, L. acidophilus, and B. bifidum.

Study limitations include relatively small sample sizes and a lack of heterogeneity regarding evaluated indices, administered amounts of probiotics, or types of species used in the supplements. There was also a lack of representation of certain demographic groups. Clinical conclusions cannot be made at this time and evidence indicates that further research is warranted.

Probiotics have been shown in literature to help support immune health and gastrointestinal function. They may also help support antioxidative status, athletic performance, and the body’s response to strenuous exercise.

By Dr. C. Ambrose, ND, MAT