Extract standardized to beta-glucans.
As an add-on it may improve the immune response; it is not a treatment.
See the study (review (Cochrane)) →⏱ 3 min read
Reishi, or ling zhi, is Ganoderma lucidum, a mushroom with a characteristic lacquered appearance (its Chinese name means "mushroom of immortality" or "spirit plant") used in traditional Chinese medicine for more than 2,000 years as a longevity tonic, mental calmative, and immune modulator; Chinese emperors and classical Taoist texts regarded it as one of the noblest herbs in the phytotherapy repertoire, a reputation that modern research has partially supported with clinical data in immunomodulation, chronic fatigue, and oncology adjunct use.
The identified active principles fall into two main families with distinct but complementary pharmacological profiles: the beta-glucan polysaccharides (especially beta-1,3/1,6-glucans from the fruiting body), responsible for most of the documented immunomodulatory effects, and the triterpenoids (ganoderic and lucidenic acids), responsible for the hepatoprotective, hypotensive, and central nervous system-modifying effects; this chemical duality is why extracts with dual standardization (percentage of polysaccharides and of triterpenoids) are the products with the most complete clinical profile.
The indication with the most established clinical use is as an immunomodulator in oncology: several Chinese trials and a Cochrane meta-analysis published in 2016 have documented that reishi added to chemotherapy or radiotherapy improves immune response and quality of life in patients with various solid cancers, without demonstrating superiority as a stand-alone antitumor treatment; fruiting-body polysaccharides stimulate the activity of NK cells, macrophages, and T lymphocytes in in vitro and in vivo studies, a mechanistic basis consistent with the clinical data.
In Japan, Ganoderma derivatives have been registered as adjunct oncology medicines for decades and are used with some frequency in integrative oncology; the data in specific cancers (breast, lung, colorectal, hepatocellular) are heterogeneous but point to consistent symptomatic benefits and a reduction in some adverse effects of conventional treatments.
In chronic fatigue syndrome and in fatigue associated with cancer, several small trials have shown significant improvements on fatigue scales, subjective energy, and quality of life with supplementation at 1,500-3,000 milligrams daily for 4-8 weeks; the effects are modest but replicable and consistent with the general adaptogenic profile described in traditional medicine.
In functional insomnia and mild anxiety, reishi has traditionally been used as a mental calmative; modern clinical data are limited but point to subjective improvements in sleep quality and reduced anxiety with supplementation over weeks, an indication consistent with effects on GABAergic receptors documented in vitro at high doses.
In chronic viral hepatitis and toxic liver disease, several Chinese studies have shown reductions in transaminases and symptomatic improvements with supplementation over months; the triterpenoids appear to be mainly responsible for the hepatoprotective effect, a traditional indication with moderate and predominantly local clinical support.
In mild hypertension and dyslipidemia, several small trials have shown modest reductions in blood pressure and improvements in lipid profile with supplementation over 12 weeks; the effects are quantitatively small and not comparable to those of specific drugs, but consistent with a profile of gentle cardiovascular modulation.
The doses studied range from 1,500 to 5,000 milligrams daily of dry fruiting-body extract (ideally standardized to at least 20-30 percent polysaccharides and 2-4 percent triterpenoids), divided into two or three doses with or without food; formulations with dual standardization are significantly better than those based only on mycelium polysaccharides; the effects on fatigue and immunity appear gradually and require at least 4-8 weeks for clinical assessment.
Generally well tolerated, with documented millennia-long use; the adverse effects described are rare and mild (digestive discomfort, dry mouth, occasionally skin rash); people with mushroom allergy may have allergic reactions and should use caution; those taking anticoagulants (warfarin, dabigatran, rivaroxaban, antiplatelet agents) should use caution because of a described mild antiplatelet effect; those taking immunosuppressants should avoid it because of an expected pharmacodynamic interaction; it is contraindicated in people with organ transplants because of a theoretical risk of rejection; in pregnancy and breastfeeding, data are limited, although it has traditionally been used without significant problems; people scheduled for surgery should stop reishi at least 2 weeks beforehand because of the antiplatelet effect.
Information, not medical advice. Scientific evidence reflects the quality of the studies.