ÃŸ-Glucans (beta-glucans) are polysaccharides of D-glucose monomers linked by glycosidic bonds. They occur most commonly as cellulose in plants, the bran of cereal grains, the cell wall of baker's yeast, certain fungi, mushrooms and bacteria. Some forms of beta glucans are useful in human nutrition as texturing agents and as soluble fiber supplements, but can be problematic in the process of brewing. Yeast and medicinal mushroom derived beta glucans are notable for their ability to modulate the immune system. Research has shown that insoluble (1,3/1,6) beta glucan, has greater biological activity than that of its soluble (1,3/1,4) beta glucan counterparts. The differences between beta glucan linkages and chemical structure, are significant in regards to solubility, mode of action, and overall biological activity.