Beta glucans are polysaccharides found in the cell walls of cereals, bacteria, and fungi. Their use to support patients undergoing chemotherapy is primarily supported by scientific investigation, though the evidence is moderate and not yet conclusive. Several studies suggest that beta glucans can modulate the immune system by activating macrophages, neutrophils, and natural killer (NK) cells, which may help counteract the immunosuppressive effects of chemotherapy. Some clinical trials in cancer patients have shown that beta glucan supplementation can reduce the incidence and severity of infections, improve white blood cell counts, and enhance quality of life. For example, a few randomized controlled trials (RCTs) have reported decreased rates of febrile neutropenia and improved recovery of immune parameters in patients receiving beta glucans alongside chemotherapy.

However, while these findings are promising, the number of high-quality, large-scale human studies is limited, and not all studies have shown significant benefits. The mechanisms by which beta glucans may reduce chemotherapy side effects are still being elucidated, and variability in beta glucan sources and formulations complicates interpretation. Current evidence suggests that beta glucans may serve as a supportive adjunct to reduce some chemotherapy-related side effects, especially those related to immune suppression, but further research is needed before widespread recommendations can be made.