NOW Beta-1,3/1,6-D-Glucan (Beta-Glucan) is a bioactive carbohydrate derived from the cell wall of Saccharomyces cerevisiae, commonly known as Bakers' yeast. Scientific studies have shown that Beta-Glucan promotes immune health through its ability to support the body's natural macrophage response. NOW Beta-Glucan is blended into a synergistic base of Maitake Mushrooms for added power.