# \(\beta\)-Glucans from Yeast--Immunomodulators from Novel Waste Resources
## 6 Yeast \(\beta\)-Glucan Administration to Humans
### Immune-Modulatory Effects of Yeast \(\beta\)-Glucan  
Clinical trials, including baker's yeast \(\beta\)-glucan, indicated favourable benefits for upper respiratory tract infections [71; 72]. Administration of \(\beta\)-glucan from brewer's yeast in two randomised, double-blind, placebo-controlled clinical trials reduced the incidence of common cold episodes in healthy subjects. Some studies have also demonstrated that \(\beta\)-glucan positively enhances the immune system after exercise [73; 74]. When yeast \(\beta\)-glucan was provided prophylactically before cycling activity, it affected the production of cytokines in response to heat and exercise [75]. In another study, when Yestimun, a commercial \(\beta\)-glucan from yeast, was administered in winter, upper respiratory tract infection (URTI) was significantly reduced during the first seven days of an episode. In this study, the incidence of URTI, severity, and duration were measured. Results demonstrated that supplementation with \(\beta\)-glucan over 16 weeks reduced the severity of physical URTI symptoms during the first week of an episode [4]. When yeast \(\beta\)-glucans were distributed to the older population to observe their effects on upper respiratory tract infections, fewer illness episodes in treatment groups than in the control were observed [71; 76]. After intensive exercise, physiological reactions can inhibit innate immune function, putting people at an increased risk of getting upper respiratory tract infections. Athletes must be able to perform, tolerate, and recover from strenuous physical activity [77; 78]. Supplementing indigestible carbohydrates such as \(\beta\)-glucan can help maintain a healthy immune system. This is because they access the large intestine rather than the small intestine. They are then presented to macrophages at this location. When macrophages are exposed to certain \(\beta\)-glucan, they exhibit increased phagocytic activity and a more anti-inflammatory pattern or phenotype [51; 79]. Thus, yeast \(\beta\)-glucan may enhance athletes' resistance to infection during training. In a study by [PERSON] et al. (2020), the effects of yeast \(\beta\)-glucan on exercise-induced immunosuppression, muscle injury, muscular function, and mood after a long treadmill session were measured. Compared to placebo, supplementation significantly lowered the degree of response and shortened the time course rise in cytokine expression and myoglobin concentrations. In this study, yeast \(\beta\)-glucan influenced muscular function, muscle injury, and mood. MCP-1 is a chemokine that affects monocyte and macrophage motility and infiltration. MCP-1 production affects insulin signalling and muscle-adipose tissue cross talk. MCP-1b down-regulation signals that regeneration has started the second stage of healing. The therapy also reduced M.I.P., MCP-1, and IL-8 levels. TNF-\(\alpha\) was similarly reduced following heated treadmill activity. Lower IL-8 levels may also indicate recovery after exercise stress [1; 80]. The molecular structure of \(\beta\)-glucan appears to play a role in their efficacy. Yeast \(\beta\)-glucan have a more branched-like network than other glucans, responsible for a more significant increase in biological activity [75]. This has been demonstrated when oat \(\beta\)-glucan did not achieve the same effects as its yeast counterparts. However, oat \(\beta\)-glucan