Dietary Supplement Purified Beta-1,3/1,6 GlucanBeta-glucan is a complex polysaccharide composed of glucose molecules extracted and purified from the cell wall of common barker's yeast, Saccharomyces cerevisiae. Beta-glucan is used to maintain or stimulates the effectiveness of the immune system. Animal and human cell culture studies have shown that beta-glucan can stimulate several aspects of immune function, such as phagocytosis and interleukin production. Source Naturals Beta Glucan uses a purification process that removes the mannoproteins and yeast residues that may reduce the effectiveness of beta-glucan.