Pooled data from 35 studies examining the potential effects of probiotics on body composition, including 1,336 participants actively involved in exercise, indicated “notable impacts of probiotic supplementation on body composition, exercise damage recovery and exercise performance.
However, there were no effects on body mass index, lean body mass, lactate dehydrogenase and myoglobin levels, reported researchers at Tehran University of Medical Sciences in Iran and Hawler Medical University in Iraq in Physiological Reports.
Giving athletes an edge
Despite the potential beneficial effects of probiotics on exercise performance and body composition, the researchers noted a relatively limited number of studies.
“Probiotics play a crucial role in regulating gut microbiota balance by inhibiting harmful bacteria growth, suppressing the production of detrimental metabolic byproducts and pro‐inflammatory cytokines, enhancing carbohydrate metabolism and modulating the immune system,” they wrote.
Exercise-induced muscle discomfort (EIMD) is a common occurrence in athletes, resulting in pain, inflammation and impaired performance. Elevated creatine kinase levels post-exercise is an indicator of muscle damage; hence, the decreased levels seen with probiotic supplementation in the study are encouraging.
Although the exact mechanisms are yet to be identified, “elevation of short‐chain fatty acids (SCFA) in the gut due to probiotics could be a contributing factor,” the researchers noted.
They added that elevated SCFAs may raise glycogen levels and enhance protein absorption, promoting muscle recovery and repair. Additionally, lactic acid bacteria possess antioxidant properties, inhibiting reactive oxygen species (ROS) production and inflammation and reducing circulating endotoxins.
“Probiotics have the potential to enhance exercise capacity by bolstering the host’s immune system function, intestinal barrier integrity, energy metabolism, mental resilience and antioxidant capability,” they concluded.
Study details
After pooling the data from 35 clinical trials with parallel or crossover designs, the results revealed a significant effect of probiotics on body weight (BW) with a weighted mean difference (WMD) of −0.55 kg, and on percentage body fat with a WMD of −0.46.
There was a “remarkable reduction effect on creatine kinase (CK) concentration overall,” and “a beneficial impact of probiotic supplementation on maximal oxygen consumption (VO2max),” the researchers wrote.
Subgroup analysis found that using probiotics for six weeks had a positive impact on BW in overweight or obese participants over the age of 30. Additionally, there was a post-exercise decrease in creatine kinase in males with normal BMI who used single-strain probiotics.
“Interestingly, taking probiotics for less than 6 weeks in trained individuals improved performance by enhancing VO2 max,” the researchers noted.
There was no significant effect on BMI, lean body mass, lactate dehydrogenase or myoglobin levels.
Due to the restricted certainty of the evidence, the researchers recommended “additional extensive and meticulously designed trials” to substantiate their findings.
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Source: Physiological Reports, 2025;13(8):e70288, doi: 10.14814/phy2.70288. “The effects of probiotic supplementation on body composition, recovery following exercise‐induced muscle damage, and exercise performance: A systematic review and meta‐analysis of clinical trials”. Authors: N.M. Shirkoohi et al.