Beta-glucans are non-starch polysaccharides made of D-glucose molecules connected by beta-glycosidic bonds. They have the potential to impart health benefits including immunomodulation. Found in mushrooms, seaweed, yeast, and cereal grains, these polysaccharides may have slightly different functions depending on their origin. The beta-glucans in cereals such as oats and barley have been found to provide benefits to cholesterol levels, obesity, and metabolic disorders, and those found in mushrooms and yeast have been found to act on the immune system.
Beta-glucans may stimulate the innate immune system. Soluble and insoluble beta-glucans act differently on the immune system to trigger an immune response, with soluble beta-glucan binding to the complement receptor 3 (CR3) and insoluble beta-glucans binding to dectin-1. CR3, found mainly in neutrophils, monocytes, and natural killer cells, interacts with toll-like receptor-2 and also mediates tumor necrosis factor-alpha through nuclear factor-kappa B (NF-kB) activation. The dectin-1 receptor is an innate immune response receptor found mainly on macrophages and dendritic cells that activates tyrosine kinase Syk and NF-kB to induce proinflammatory cytokines. The activation of macrophages also initiates cellular and humoral immune response including an inflammatory response. Additionally, beta-glucans support the T helper (Th) cells (Th1/Th2) balance by mediating Th1 and Th17 cells, which may suppress Th2 cells. This may provide benefits in allergies.
Beta-glucans may also support a healthy immune response. They may help build a protective innate immune memory that supports the immune system to work better when exposed to certain pathogenic microorganisms, especially those that have beta-glucans in their cell walls. In addition to acting directly on the immune system, beta-glucans may also be fermented by beneficial bacteria in the gut to support a healthy microbiome and synthesize short-chain fatty acids (SCFA). The SCFAs may also impart immunomodulatory and anti-inflammatory properties and support a healthy microbiome. Additionally, beta-glucans may also directly exert antioxidant activity to support redox balance.
Clinical studies support the immunomodulating benefits of beta-glucans. In one study on marathon runners, consuming insoluble beta-glucan from yeast led to a significantly reduced severity of upper respiratory tract infection and fewer symptomatic days. Beta-glucan supplements derived from mushrooms have been found to help prevent respiratory disease in children and significantly decrease the frequency of flu and flu-like disease, and they also impart anti-allergenic effects. Studies have also found that consuming mushroom products rich in beta-glucans may improve overall well-being in healthy adults, especially in those with lower well-being before supplementation, as well as reducing upper respiratory tract infections in athletes.
As a complex system, the immune system is supported by a variety of nutrients, phytochemicals, and other beneficial molecules derived from food, such as beta-glucans. Consuming foods rich in beta-glucans, such as cereals and mushrooms, may impart some of the immunomodulating benefits. Supplementing may also support a healthy immune response.*
By Kendra Whitmire, MS, CNS