 β-glucans found in the cell walls of yeast contain a 1,3 carbon backbone with elongated 1,6 carbon branches.Other sources include seaweed, and various mushrooms, such as lingzhi, shiitake, chaga, and maitake, which are under preliminary research for their potential immune effects.In the diet, β-glucans are a source of soluble, fermentable fiber – also called "prebiotic fiber" – which provides a substrate for microbiota within the large intestine, increasing fecal bulk and producing short-chain fatty acids as byproducts with wide-ranging physiological activities.