The effect of short-term probiotic supplementation on gut flora of elite athletes

Optimal immune function is emerging as a key contributor tosporting performance (Berg et al. Exerc Immunol Rev,1999,5, 78–95). There is increasing scientific interest in the preventionand management of gastrointestinal (GI) illness inathletes travelling to countries with varied diet and sanitationconditions. This study aims to examine the effectiveness ofprobiotic supplementation in altering gut flora and preventingtravelers’ diarrhea (TD) in elite athletes traveling to a highriskcountry. Eight athletes were supplemented for 8 weekswith Lactobacillus acidophilus, Bifidobacteria lactis, andLactobacillus rhamnosus (1/day). Stool samples were takenat baseline, directly before traveling (~2 weeks later), and atreturn. Fluorescent in situ hybridization was used to assessbacterial concentrations of total eubacteria, bifidobacteria, andbacteroides (log10 bacteria/g fresh feces), and gas chromatographyto assess short-chain fatty acid (SCFA) concentrations(mmol/g fresh feces), of three fecal samples taken at baseline,precompetition, and postcompetition. Participants used a dailylog to record symptoms of TD, classified using the WorldHealth Organization (WHO) definition of ≥3 loose or waterystools in a 24-hr period (Allen et al., Cochrane Review, 2009,1, 1–72). There were no statistical changes to total eubacteria,bifidobacteria, bacteroides, or SCFA concentrations, but therewas a trend towards an increase for all bacterial groups frombaseline to precompetition. Statistically significant relationships(p ≤ .05) were also detected between average bifidobacteria andn-valeric concentration (r = .520) and average bacteroide andn-butyrate concentration (r = –.557). Fifty percent of athletesreported TD symptoms. Probiotic supplementation led to smallmodulations in athlete gut flora that may be clinically relevantto health and indirectly to performance. Supplementation wasunable to prevent episodes of TD in 50% of athletes.