Mushroom beta-glucans as anticancer and therapeutic agents: a focus on their mechanism of action

β-glucans are biologically active polysaccharides derived from natural sources, especially mushrooms, renowned for their immunomodulatory, antitumor, and anti-inflammatory properties. These compounds can be safely consumed as dietary supplements or as part of one's daily diet. Chemoprevention is a crucial approach in reducing cancer development and tumor progression including the use of natural substances to impede, arrest, or reverse carcinogenesis. β-glucans, especially those from mushrooms, have been recognized as effective chemopreventive and adjuvant agents when combined with standard chemotherapy. They appear to operate through various mechanisms and may exhibit additive or synergistic effects. While in vitro and animal studies have consistently demonstrated their medical potential, clinical investigations into the precise mechanisms of action remain limited. Therefore, understanding the specific molecular changes that drive cancer development and progression, and developing anticancer and adjuvant chemotherapeutic drugs, which improve cancer treatment is still a main challenge in this field. Therefore, this review aims to summarise recent research findings on the anticancer effects of selected mushroom β-glucans, covering a range of preclinical (in vitro and in vivo) and several clinical studies, with a focus on their chemopreventive and chemotherapeutic potential. We also discuss their potential molecular mechanisms of action and provide a brief overview of the classification, structural characteristics, sources, and origin of β-glucans derived from various edible mushrooms.