Plain language summary
Gastrointestinal (GI) symptoms are common in athletes participating in marathon running. The purpose of this study was to evaluate the effects of probiotic supplementation on GI symptoms and markers of GI permeability and damage during marathon training and racing. 24 runners took part in this double-blind, randomised trial. Participants took a probiotic supplement containing 25 billion organisms (Lactobacilli and bifidobacterial) or placebo for 4 weeks prior to the marathon race. Blood samples were taken before supplementation, pre and post marathon. Participants also completed a questionnaires regarding GI symptoms. All runners experienced GI symptoms during the marathon. Runners supplementing with probiotics reported fewer and less severe GI symptoms, both in training and during the race, and also showed increased performance during the race compared to the placebo group. There was no association between GI symptoms and markers of GI permeability and damage, although both were increased post-race in all participants. The authors conclude that athletes participating in endurance events, where GI symptoms are common and likely to affect performance, could consider probiotic supplementation in the weeks prior to competition.
Abstract
PURPOSE To evaluate the effects of probiotic supplementation on gastrointestinal (GI) symptoms, circulatory markers of GI permeability, damage, and markers of immune response during a marathon race. METHODS Twenty-four recreational runners were randomly assigned to either supplement with a probiotic (PRO) capsule [25 billion CFU Lactobacillus acidophilus (CUL60 and CUL21), Bifidobacterium bifidum (CUL20), and Bifidobacterium animalis subs p. Lactis (CUL34)] or placebo (PLC) for 28 days prior to a marathon race. GI symptoms were recorded during the supplement period and during the race. Serum lactulose:rhamnose ratio, and plasma intestinal-fatty acid binding protein, sCD14, and cytokines were measured pre- and post-races. RESULTS Prevalence of moderate GI symptoms reported were lower during the third and fourth weeks of the supplement period compared to the first and second weeks in PRO (p < 0.05) but not PLC (p > 0.05). During the marathon, GI symptom severity during the final third was significantly lower in PRO compared to PLC (p = 0.010). The lower symptom severity was associated with a significant difference in reduction of average speed from the first to the last third of the race between PLC (- 14.2 ± 5.8%) and PRO (- 7.9 ± 7.5%) (p = 0.04), although there was no difference in finish times between groups (p > 0.05). Circulatory measures increased to a similar extent between PRO and PLC (p > 0.05). CONCLUSION Probiotics supplementation was associated with a lower incidence and severity of GI symptoms in marathon runners, although the exact mechanisms are yet to be elucidated. Reducing GI symptoms during marathon running may help maintain running pace during the latter stages of racing.
Methodological quality
Jadad score
:
5
Allocation concealment
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Yes
