Reishi Mushroom

What is reishi?

Reishi, also called lingzhi, is a hard, glossy bracket fungus that grows on wood. It has been used in Chinese and Japanese traditional medicine for centuries, usually as a hot-water decoction or powder. Its main compounds of interest are polysaccharides, including beta-glucans, and bitter triterpenes called ganoderic acids. The National Cancer Institute notes that several closely related species are sold under the reishi name, which makes comparing products and studies harder (NCI PDQ).

What the research says

Heart and metabolic markers

Reishi is often marketed for cholesterol and heart health, but the best summary of the human evidence is negative. A Cochrane review identified five trials with 398 participants. In the studies that could be pooled, reishi at 1.4 to 3 grams a day for 12 to 16 weeks did not produce statistically or clinically significant changes in HbA1c, total cholesterol, LDL cholesterol, triglycerides, blood pressure or body-mass index compared with placebo. People taking reishi were somewhat more likely to report adverse events, although none were serious. The authors concluded the evidence does not support reishi for cardiovascular risk factors (Klupp et al., 2015).

Bleeding and blood clotting

Laboratory studies once suggested reishi might affect platelets. In a randomized, placebo-controlled trial, 40 healthy volunteers took 1.5 grams a day or placebo for four weeks, and no measure of clotting or platelet function changed (Kwok et al., 2005). That is reassuring, but the trial was small and short and did not include people on blood thinners.

Cancer care

Reishi has been studied mostly as a complementary therapy in cancer, where the NCI summary describes the human data as limited and mixed (NCI PDQ). These studies do not tell us much about everyday heart health.

Liver safety

Case reports describe acute liver injury after taking reishi powder, including a 2004 report of hepatotoxicity linked to a reishi formulation (Yuen et al., 2004) and a 2023 case in a man who combined reishi powder with alcohol and recovered after stopping (Guedikian et al., 2023). Such events appear rare, but they are a reason to stop and see a doctor if you notice dark urine, yellowing skin or abdominal pain.

How it’s used in supplements

Reishi appears in capsules, powders, teas and mushroom coffee blends, often as a hot-water extract of the fruiting body or as spore powder. Doses in human trials have generally been between 1 and 5 grams a day, so the few hundred milligrams found in many multi-mushroom blends are much lower than what has been tested. Look for products that name the species, the part used (fruiting body, mycelium or spores) and the extraction method. Talk to your doctor before using reishi if you take blood thinners, diabetes medicines, blood pressure medicines or immune-suppressing drugs, have liver disease, or are pregnant or breastfeeding.