Effects of yeast ß-glucans for the prevention and treatment of upper respiratory tract infection in healthy subjects: a systematic review and meta-analysis.

PURPOSE: Yeast ß-glucans are known for their immune-modulating effects; however, their effects on human upper respiratory tract infections (URTIs) remain unclear. The aim of the present study was to use a systematic review and meta-analysis approach to investigate the effects of yeast ß-glucans for the prevention and treatment of URTIs in healthy subjects. METHODS: Databases including Pubmed, Web of Science, EMBASE and the Cochrane Library were searched and 13 RCTs investigating the effects of yeast ß-glucans on the incidence, duration, and severity of URTIs in healthy subjects were included. RESULTS: The results showed that compared to the placebo group, yeast ß-glucan could significantly reduce the incidence of URTIs (OR = 0.345, 95% CI = 0.192 to 0.620, p < 0.001), decrease the average number of URTI episodes (SMD = - 0.315, 95% CI = - 0.500 to - 0.130, p < 0.05), and decrease the duration of URTIs (SMD = - 0.312, 95% CI = - 0.561 to - 0.064, p < 0.001). Improved severity of symptoms was found in yeast ß-glucan group compared to the placebo group in the majority of included studies. In addition, yeast ß-glucan was well tolerated and safe in general. CONCLUSION: These findings suggest a positive effect of yeast ß-glucans on human URTIs. However, due to the high heterogeneity and small number of included studies, more high-quality research and clinical trials are warranted.