Beta-glucan is a polysaccharide composed of D-glucose monomers linked by β-glycosidic bonds, commonly found in the cell walls of cereals like oats and barley, as well as in yeasts, fungi, and bacteria. It exists in various forms, such as (1→3)-β-D-glucan and (1→3)(1→4)-β-D-glucan, with the latter being prominent in cereals. This compound is renowned for its health benefits, including immune modulation, cholesterol reduction, and potential anti-cancer properties, due to its ability to activate macrophages and enhance gut health. Physically, beta-glucan is a white to off-white powder that can form viscous solutions or gels in water, depending on its molecular weight and branching. It plays a crucial role in food science as a soluble fiber, improving texture in products like bread and beverages, and is studied for its prebiotic effects on the microbiome. Chemically, it is a linear or branched polymer with varying degrees of polymerization, making it resistant to digestion in the upper gastrointestinal tract but fermentable by gut bacteria. Research from sources like the Journal of Agricultural and Food Chemistry highlights its solubility in hot water for certain types, while it remains stable under acidic conditions. Overall, beta-glucan's biological activities make it a valuable compound in nutrition and pharmaceuticals, with ongoing studies exploring its role in metabolic diseases and immune disorders.