The Effects of Multi-Strain Probiotic SLAB51 Intake on Aerobic Performance and Oxidative Stress Responses in Elite Athletes: A Randomized Crossover Trial.
These null findings suggest SLAB51's benefits may be more specific to exercise duration and antioxidant enzyme activity than broader aerobic capacity or oxidative damage markers
Methods
The study used a randomized, double-blind, placebo-controlled crossover design with assessments at baseline, after a single intake, and after one week of intake.
Participants received SLAB51 and placebo for one week each, separated by a two-week washout period
Assessments were performed at three time points: baseline, after a single intake, and after one week of intake
Data were analyzed using two-way repeated-measures ANOVA supplemented by post hoc linear mixed-effects models accounting for the crossover design
The study population consisted of elite athletes
What This Means
This research suggests that taking a specific multi-strain probiotic called SLAB51 for one week may help elite athletes exercise for longer. In this carefully designed study where athletes took both the probiotic and a placebo at different times (so each person acted as their own comparison), those taking SLAB51 were able to exercise for about 33 seconds longer on a treadmill fitness test than when taking the placebo. While this may sound small, in competitive sports even small improvements in endurance can be meaningful. The researchers also found that athletes on SLAB51 spent more time exercising at high intensity (above a threshold called RER 1.0) and showed higher levels of a protective antioxidant enzyme called superoxide dismutase before exercise.
However, not everything improved. The probiotic did not appear to affect maximum oxygen uptake (a key measure of aerobic fitness), how quickly lactic acid cleared from the blood after exercise, or markers of oxidative damage in the body. This suggests SLAB51 may have a more targeted effect on exercise endurance and the body's antioxidant defenses rather than broadly changing cardiovascular fitness.
This research matters because athletes are always looking for safe, legal ways to improve performance and recovery, and probiotics are increasingly being studied in this area. The study's rigorous crossover design — where each athlete served as their own control — adds confidence to the findings. However, the supplementation period was only one week, and longer studies with larger groups would be needed to fully understand whether these benefits persist and whether they apply to non-elite or recreational athletes as well.
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Lee S, Kim S, Park J, Yun H, Yoon J. (2026). The Effects of Multi-Strain Probiotic SLAB51 Intake on Aerobic Performance and Oxidative Stress Responses in Elite Athletes: A Randomized Crossover Trial.. Nutrients. https://doi.org/10.3390/nu18193299