The term “beta-glucan” refers to a class of soluble fibers found in many plant sources. The best documented use of beta-glucan involves improving heart health; the evidence for benefit is strong enough that the FDA has allowed a “heart healthy” label claim for food products containing substantial amounts of beta-glucan.1 Much weaker evidence supports the potential use of certain beta-glucan products for modifying the activity of the immune system.

Beta-glucan is not an essential nutrient. It is found in whole grains (especially oats, wheat, and barley) and fungi such as baker’s yeast, Coriolus versicolor, and the medicinal mushrooms maitake and reishi.

Different food sources contain differing amounts of the various chemical constituents collectively called beta-glucan. Grains primarily contain beta-1,3-glucan and beta-1,4-glucan. Fungal sources contain a mixture of beta-1,3-glucan and beta-1,6-glucan. Purified products containing only the 1,3 form are also available.