Advances in the preparation, bioactivities, and structure-activity relationship of β-glucans

β-Glucans, a group of polysaccharides composed of d-glucose units linked predominantly via β-(1 → 3), β-(1 → 4), and/or β-(1 → 6) glycosidic bonds, are widely distributed in cereals, fungi, and algae. Extensive studies have demonstrated that β-glucans possess diverse bioactivities both in vitro and in vivo, including antioxidant, neuroprotective, anti-inflammatory, and immunomodulatory effects. This review presents a comprehensive summary of recent advances in the preparation, purification, and structural characterization of β-glucans, with particular focus on their bioactive mechanisms and structure-activity relationships. In addition, it discusses chemical modifications that significantly enhance the biological functions of β-glucans. Overall, this review provides valuable insights into the functional properties of β-glucans and supports their potential applications in medicine, food, and cosmetics.