Mesima, derived from the mushroom Phellinus linteus, has been studied for its potential adjunctive benefits during chemotherapy, particularly in East Asian countries. Its traditional use in Asian medicine mainly revolves around general immune support and anti-tumor effects, but recent decades have seen a growing body of preclinical and some clinical research exploring its ability to modulate immune responses and potentially reduce chemotherapy-induced side effects.

Scientific studies have investigated Mesima's polysaccharides and other bioactive compounds, demonstrating immune-modulatory, anti-inflammatory, and antioxidant effects in vitro and in animal models. These properties could theoretically help mitigate certain side effects of chemotherapy, such as immunosuppression and inflammation. Some small-scale clinical trials and case reports, largely from Korea and Japan, suggest that Mesima extracts may improve quality of life, reduce fatigue, and enhance immune parameters in cancer patients undergoing chemotherapy. However, these studies are often limited by small sample sizes, lack of rigorous controls, and heterogeneous methodologies.

Overall, while there is emerging scientific interest and some preliminary evidence supporting Mesima’s use for reducing chemotherapy side effects, robust clinical validation is lacking. Larger, well-designed randomized controlled trials are necessary to confirm efficacy and safety. At present, the evidence is promising but limited, justifying a rating of 2 out of 5.