Beta-glucans are polysaccharides consisting of D-glucose monomers connected via β-glycosidic linkages, predominantly β-1,3 and β-1,4 bonds in cereal sources such as oats and barley, or β-1,3 with β-1,6 branches in yeast and fungi. They function as structural components in cell walls and exhibit significant physiological effects including cholesterol-lowering via bile acid binding, immunomodulation through receptor interactions like Dectin-1, and prebiotic activity supporting gut microbiota. In food applications, oat beta-glucans form viscous gels that improve texture, stabilize emulsions, and contribute to satiety. Peer-reviewed studies confirm their efficacy in reducing LDL cholesterol and postprandial glucose spikes, with GRAS status supporting widespread use in functional foods and supplements.