Across 3 studies (all reviews), all reported beneficial effects on gastrointestinal symptoms. Effect sizes were predominantly small (2 studies) with one moderate. The evidence is limited to reviews without primary data, and no statistically significant findings were reported.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. All studies are reviews, not primary clinical trials, limiting the strength of the evidence. No statistically significant findings were reported across studies. Only one study specifically focused on athletes; the remaining studies included general adult populations. No dose, duration, or form information was extracted, preventing specific recommendations. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed).
Only slight evidence was found for a positive effect of probiotics on GI symptoms in athletes during training, exercise, and competition
probiotics have a beneficial effect on mental health, cognitive functions, sleep, gastrointestinal, and upper respiratory symptoms in adult humans.
studies that demonstrated the probiotic potential of enterococcal consumption (e.g., gastrointestinal and respiratory disease, hyperlipidemia alleviation, as well as infection prevention)