Research appearing in the International Journal of Sports Nutrition, Exercise and Metabolism (2011 Feb; 21(1): 55-64) looked at the use of probiotics and their effect on the immune systems of 58 athletes. The 58 subjects of the study were randomly assigned to receive either a probiotic supplement (Lactobacillus casei Shirota) for a period of 16 weeks. The placebo group had 36% higher incidence of upper respiratory infections (URTI) compared to the group receiving the supplement. According to the authors, “Regular ingestion of LcS appears to be beneficial in reducing the frequency of URTI in an athletic cohort, which may be related to better maintenance of saliva IgA levels during a winter period of training and competition.”