Beta glucans are found in the cell walls of bacteria, yeasts, algae, fungi and various plants. Yeast-derived beta glucans are of great medical interest and have received much attention and study.
Beta glucan is a polysaccharide, or complex sugar, comprised of D-glucose monomers. As many as 250,000 glucose molecules may be contained in each beta glucan.
The linkage pattern in beta glucan consists of primarily beta-1,4 linkages. Unlike other glucose polysaccharides, like cellulose, beta glucan has a beta-1,3 linkage occurring in between approximately every three or four beta-1,4 linkages.
The beta-1,3 linkage breaks up the linear chain and makes it flexible, leading to a long cylindrical molecule.
The structure of beta glucan allows it to bind to a lectin site on leukocytes, leading to a nonspecific immune activator.