Fungal β-1,3-glucans: Cell Wall Constituents That Promote Gut Health Through Innate Immune Modulation.

Fungal β-1,3-glucans are structurally conserved polysaccharide components of the fungal cell wall that exhibit potent immunomodulatory activity. These molecules are recognized by pattern recognition receptors, Toll-like receptors, complement receptor 3, lactosylceramide, scavenger receptors, and EphA2. Binding of β-1,3-glucans through these receptors triggers coordinated innate and adaptive immune responses such as cytokine production, phagocytosis, and trained immunity. In addition to receptor-mediated immune activation, dietary β-1,3-glucans function as fermentable prebiotic fibers that modulate gut microbiota composition, increase short-chain fatty acid production, and strengthen epithelial barrier integrity. These combined immunological and microbiome-mediated effects position β-1,3-glucans as key regulators of gut homeostasis. Preclinical and emerging clinical evidence supports broad therapeutic potential across multiple disease domains, including inflammatory bowel disease, metabolic disorders, respiratory infections, and cancer. In oncology, β-1,3-glucans enhance anti-tumor immunity, improve responses to monoclonal antibodies and chemotherapy, and serve as promising adjuvants in vaccine-based strategies. Additionally, β-1,3-glucan is widely used as a biomarker for invasive fungal infections and represents a validated target of antifungal therapies such as echinocandins. Despite these advances, clinical translation remains limited by heterogeneity in glucan source, structure, and formulation, as well as a lack of appropriately powered, standardized human clinical trials. Future efforts should focus on clarifying mechanisms of action, as well as rigorous clinical evaluation, to fully define the therapeutic utility of fungal β-1,3-glucans.