The athletes were staff and students at the university who were involved in regular intensive sports training, such as cycling, triathlon, middle-long distance running or swimming.
The results confirmed that daily consumption of Yakult was effective in reducing the incidence of common colds (i.e., upper respiratory tract infections, URTIs) in the athletes. In an earlier study it has been demonstrated that as a group, athletes are susceptible to infections due to a depression of their immune system.
The study was fully described and published online in the scientific peer-reviewed journal International Journal of Sport Nutrition & Exercise Metabolism.
The double-blind trial was conducted in 84 endurance athletes. Subjects were divided into two groups: 42 received Yakult (6.5 x 109 live cells of a probiotic strain LcS in each bottle) and 42 received a placebo. After subjects consumed the given drink twice daily for 16 weeks, the drinking effect on incidence of URTI and immune parameters was examined.
The summary of the results is as follows:
The proportion of subjects from the Yakult group who experienced one or more weeks with URTI symptoms was 66%, which was significantly lower than that from the placebo group (90%).
Saliva IgA concentration, which can be lowered by prolonged hard sports, was higher in the Yakult group than in the placebo group.
Based on these findings, the researchers concluded that daily consumption of fermented milk drink containing LcS lowers the incidence of URTI in athletes who are engaged in prolonged hard sports. The amount of sIgA antibodies was kept in an optimal condition, which can be considered as one of the factors for the effect.
Professor Michael Gleeson (Professor of Exercise Biochemistry in the School of Sport, Exercise and Health Sciences) who led the study at Loughborough University commented: “There is relatively little evidence for the effectiveness of so-called dietary immunostimulants in the athletic population but this study suggests that a probiotic product may help to reduce the risk of infection. Athletes hate the thought of picking up colds as even minor ailments can impair their training and performance or even stop them from competing.”
Yakult Honsha Co., Ltd. participated in this study as sponsor by providing funding and test samples.
Dr. Haruji Sawada, PhD, the director of the Yakult Central Institute for Microbiological Research (YCIMR) said, “It is a valuable result that the daily consumption of our product, Yakult, is proven to contribute to the maintenance of a good state of upper respiratory tract in healthy sports persons. This study has resulted in important data that are further evidence of immune benefits associated with drinking Yakult.”