This meta-analysis compiled data from 13 randomized and controlled trials assessing the effects of yeast beta-glucans on upper respiratory tract infections (URTI) in healthy subjects. Results showed that yeast beta-glucan could reduce the incidence of URTI (OR = 0.345, 95% CI: 0.192-0.620, p < 0.0001). It also reduced the average number of URTI (p < 0.05) and the duration of URTI (p < 0.001). Finally, severity of symptoms was also lower in the majority of studies following the beta-glucan supplementation. Based on these results, it is possible to conclude on the beneficial effects of yeast beta-glucan on URTI in healthy subjects.

Zhong K, Liu Z, Lu Y, Xu X. Effects of yeast β-glucans for the prevention and treatment of upper respiratory tract infection in healthy subjects: a systematic review and meta-analysis. Eur J Nutr. 2021 Apr 26.