Reishi has been used in East Asian medicine for over two thousand years, earning the nickname "mushroom of immortality" in Chinese tradition, where it was historically so highly regarded that it was reserved for emperors and nobility rather than common use. Known as "lingzhi" in China and "reishi" in Japan, it appears frequently in classical Chinese medical texts and art, often depicted alongside deities and immortals as a symbol of health, longevity, and spiritual potency.
Unlike many remedies that grow abundantly, wild reishi was historically rare and difficult to cultivate, which contributed significantly to its elevated, almost mystical status — a genuinely scarce natural product commanding real value long before modern cultivation techniques made it widely available. Today it's one of the most heavily studied medicinal mushrooms in clinical research, with the modern science offering a more measured picture than the "mushroom of immortality" reputation suggests.
Reishi's clearest modern evidence relates to fatigue and general well-being, alongside measurable immune effects. An 8-week randomized, placebo-controlled trial in 132 patients with neurasthenia (a fatigue-related condition) found significant improvement in fatigue scores. A separate 2016 randomized trial in breast cancer survivors found reishi spore powder significantly reduced fatigue and improved quality of life after four weeks. On the immune side, more recent trials have found reishi beta-glucan significantly increases natural killer (NK) cell activity and T-lymphocyte counts — a real, measurable immune effect, though distinct from the vaguer popular claim of "boosting immunity" broadly.
Where reishi's evidence clearly falls short of its popular reputation: a rigorous 16-week randomized controlled trial found no meaningful improvement in blood glucose or lipids in people with type 2 diabetes and metabolic syndrome, directly contradicting cardiometabolic claims sometimes made for it. Reviewers also flag an important practical caveat — "reishi" isn't one standardized product; fruiting body, spores, and mycelium extracted different ways can vary significantly in their actual compound content, and rare cases of liver injury have been reported, meaning quality and sourcing matter more than usual.
Traditionally prepared as a hot water decoction (the fruiting body is too tough and bitter to eat directly), simmered for extended periods; modern preparations use standardized extracts.