Krishna Raja Muthuraman, Tatsuya Kato, Kisako Kusano, Yukiko Moriya, Enoch Y. Park
β-Glucans are non-starch polysaccharides derived from various natural sources, including cereals, fungi, yeast, algae, and bacteria. Their structures determine their functions: cereal-derived β-glucans from oats and barley have mixed β-(1,3) and β-(1,4) linkages for heart and blood sugar benefits, while fungal and yeast types have β-(1,3) backbones with β-(1,6) branches that confer potent immunomodulatory properties through their interaction with pattern recognition receptors on immune cells. This review comprehensively explores the various physiological effects of β-glucans, focusing on their mechanisms of action in metabolic health, anti-inflammatory, antioxidant, and immunotherapeutic applications. It examines how β-glucans improve glycemic control by increasing insulin sensitivity, modulating the gut microbiome, and reducing cholesterol levels through enhanced bile acid excretion. Additionally, it discusses their anti-inflammatory actions through the modulation of key signaling pathways, antioxidant effects via the Nrf2 activation, and their immunomodulatory role in neonatal and therapeutic contexts, showcasing their potential as biological response modifiers for a wide range of diseases, including chronic inflammation, metabolic disorders, and infections. The findings confirm that the specific source and structural properties of β-glucans are crucial for their efficacy, making them valuable components in the development of functional foods, nutraceuticals, and pharmaceuticals.