β-glucan is a generic term for insoluble dietary fibers exerting various effects on the immune system. As a group, β-glucans are non-cellulose polysaccharides composed of a glucopyranose as the main constituent sugar with β configuration, having a β- (1,3)-linked glucopyranose main chain as a common feature. β-glucans are absorbed through the intestine. Since the 1980s, there have been many studies reporting various effects of β-glucans on the immune system, including reports on receptors that have slowly clarified their recognition system and action mechanisms. However, these studies focused mostly on treatments of infectious diseases and tumors; thus, the effects of β-glucans ingested in food as dietary fiber and their mechanisms of action remain largely unknown. The uptake of β-glucan into the body may be resemble that of proteins, which are soluble polymers, and insoluble material such as dietary fiber. Dietary fibers have varied structures, with wide-ranging solubility and physiological effects. Understanding whether these substances are actually taken up, how they exert their effects, and their metabolism after being taken up are important issues when considering the functionality and safety of dietary fibers.
Author(s): Shingo Hino, Naomichi Nishimura, Tsukasa Matsuda, and Tatsuya Morita