Beta-glucans are a type of fiber found in the cell walls of cereals, algae, bacteria, and fungi. Their natural functions range from glucose storage to cellular and whole-plant structural integrity and to cell protection. Beta-glucans can be taken as a supplement or consumed as part of the diet, with the richest dietary sources being oats, barley, oyster mushrooms, and shiitake mushrooms.[1]
All beta-glucans consist of chains of glucose molecules linked via β-glycosidic bonds, but the chain length, branching, and types of β-linkages can vary, leading to differences in biological activity and physical characteristics. For example, cereal beta-glucans are soluble, consisting of unbranched chains of glucose units linked with a mixture of β-(1,3) and β-(1,4) bonds. On the other hand, fungal beta-glucans can be soluble or insoluble, and their glucose units are linked with β-(1,3) bonds, with or without branches attached via β-(1,6) bonds. While beta-glucans from oats and barley demonstrate some favorable effects on metabolic health, beta-glucans from yeasts and mushrooms are better known for their immune-modulating properties.[2]