The Effects of probiotic supplementation in athletes

This study is investigating whether a four-week course of daily probiotic supplementation can improve performance and immune function in male runners who train and compete in the heat. The gut microbiome — the community of bacteria living in our digestive tract — plays an important role in immune function, and probiotics may support immunity and help athletes handle the physical stress of exercising in hot conditions. Participants in this crossover trial take either a probiotic or a placebo for four weeks, then swap groups. After each four-week period, they complete a running time trial in the heat, and their immune markers (including IgA levels in saliva) are measured. This design means every participant experiences both the probiotic and placebo, making the comparison more accurate. This trial is open to healthy, fit men aged 18 to 45 who include running as part of their regular exercise routine. To ensure the results are meaningful, participants must be non-smokers and must not have used antibiotics, probiotic supplements, or select fermented dairy products in the three weeks prior to the study.