Beta-Glucans are natural bioactive carbohydrates, with those derived from certain yeasts and fungi being known for their ability to support the immune system. Jarrow Formulas Beta Glucan is a high purity extract from the cell walls of a proprietary Baker's yeast (Saccharomyces cerevisiae) strain with a unique molecular structure comprised primarily of (1,3)- -linked glucose chains (andgt75%) and a relatively small number of (1,6)- -linked side chains.