Variety of β-glucans: properties, adequate and clinically effective doses

Abstract

A review of the existing literature on the problem in recent years was carried out using the RSCI, CyberLeninka, Pubmed, and ReserchGate databases. Structurally, βglucans are complex natural polysaccharides consisting of monomeric βD-glucose units covalently linked by glycosidic bonds in various positions. βGlucans are found in bacteria, algae, edible fungi (bodies and cultivated mycelium) and cereals. According to the source of origin, βglucans are classified into cereal and non-cereal. Grain-derived βglucans (oats, barley, wheat, and rice) typically have 1,3–1,4 glycosidic linkages with no 1,6-linkages or branches, while non-grain-derived βglucans (baker’s yeast, edible mushrooms, bacteria) have linear (1,3) chains with long branching chains 1,6. The functional properties of βglucans are determined by the length of the backbone (degree of polymerization), the ratio of bonds 1.3:1.4 or bonds 1.3:1.6 (degree of branching), branching interval, side chain size and molecular weight. Grain βglucans are classified as dietary fiber in terms of their properties and mechanism of action. The effective dose of cereal βglucans, which provides efficacy in metabolic disorders (glucose, cholesterol levels) and gastrointestinal functions, as well as a probiotic effect, is from 3 to 8 g (most often 4.5 g) with a duration of intake of at least 3 weeks. Non-cereal (predominantly from fungi and yeast) βglucans have a 1,3 and 1,6 bond structure and are recognized by several receptors including dectin 1, complement receptor 3 (CR 3) and toll-like receptors (TLRs) and have more pronounced immunomodulatory functions. The main mechanisms of their action have been established in vivo experiments or animal models. Non-cereal βglucans are used as adjuvants in drug therapy at doses ranging from 20 mg for the common cold to 750 mg for cancer. In accordance with the domestic legal framework governing the use of food ingredients in the production of dietary supplements and specialized food products, βglucans are not separated by their source of origin. The currently established adequate level of intake of these polysaccharides, regardless of the source of their receipt, is 200 mg/day, and the upper acceptable level is 1000 mg/day. An analysis of literature data indicates the need to differentiate βglucans and increase the permitted doses of cereal βglucans to the level established for soluble dietary fibers.