Educational Resources

Quick literature review on probiotics and sports performance

The best recent evidence that meets PRISMA criteria for systematic reviews and meta-analyses suggests that probiotics may produce a small to moderate improvement in overall sports performance. However, the effect appears to be concentrated mainly in endurance tests, some recovery markers, and, with considerably greater consistency, indirect outcomes such as gastrointestinal symptoms and infectious/immune burden. The 2026 Bayesian review included 21 RCTs and 685 participants and estimated an overall effect of μSMD 0.38, with a clearer signal in endurance performance (μSMD 0.74) and in VO₂max based on cycle ergometer testing (μSMD 2.21). The 2025 meta-analysis found improvements in VO₂max (WMD +1.55 mL/kg/min) and a reduction in post-exercise creatine kinase (WMD −45.57 IU/L), although with moderate to low certainty of evidence. The 2022 meta-analysis focused on trained populations also found a small positive effect in predominantly aerobic tests (SMD 0.29).

When the analysis is restricted to earlier and more conservative systematic reviews, the conclusion remains cautious: direct ergogenic evidence is heterogeneous and often inconsistent, but probiotics appear to help more often with GI symptoms, URTI, inflammation/oxidative stress, and training continuity than with large increases in pure performance. In 2021, a review of endurance athletes found that only 3 out of 9 studies showed a direct performance benefit; the 2022 and 2023 reviews reiterated that much of the positive signal is indirect and dependent on strain, dose, duration, and type of athlete.

The most defensible pattern for practical use is the following: not all “probiotics” are equivalent, effects are strain-specific, the best current fit appears to be in endurance sports, and the dose range with the most consistent signal is around 10⁹–10¹¹ CFU/day or, in highly trained populations, ≥30 × 10⁹ CFU/day, generally for 4–8 weeks. The central problem is not so much a total absence of effect, but rather methodological heterogeneity and the small sample size of most trials.