About this material
In the MushroomReferences.com catalog, the Reishi category is one of the largest: 58 publications. Most of them, however, are preclinical work (in vitro, animal models). This review collects the directions that have human clinical data, and honestly marks the weak points of the evidence base. The species card with the botanical description is at Reishi.
What reishi is
Reishi (Ganoderma lucidum) is a wood-decay polypore from the Polyporaceae family. In East Asia it is known as "lingzhi" (Chinese), "reishi" (Japanese), "yeongji" (Korean). It has been used in traditional Chinese medicine for more than 2000 years. It is rare in nature, so the overwhelming majority of commercial material is cultivated (on wood blocks, sawdust, grain).
Two key groups of active substances
- β-(1→3)/(1→6)-glucans — the polysaccharide fraction responsible for immunomodulating action. The same group as in most studied wood-decay fungi (cf. Beta-glucans and immunity).
- Triterpenoids (ganoderic acids, lucidenic acids and others) — a low-molecular-weight fraction with hepatoprotective, anti-inflammatory and sedative action.
The ratio of these fractions in commercial products varies widely, complicating comparison across studies.
Clinical data: what exists
Immunomodulation
Several small RCTs in healthy volunteers and immunodeficient patients showed:
- moderate enhancement of NK-cell activity and lymphocyte proliferation;
- increased cytokine production (IL-2, IFN-γ) in response to stimulation.
The effect reproduces in small samples (n = 20–60), but large multicentre RCTs are few.
Oncology (adjuvant therapy)
This is the most reproducible clinical direction. Several meta-analyses and large cohort studies in Asia showed that taking reishi extracts alongside chemo- or radiotherapy:
- improves patients' quality of life (less fatigue, better appetite);
- in some studies — increases tumour response to treatment.
However, direct antitumour action of reishi in clinical conditions is not confirmed. A detailed look at adjuvant use of mushroom supplements is in Mushroom supplements in integrative oncology.
Sleep and anxiety
Several small RCTs (n = 30–80) showed that taking reishi for 4–8 weeks:
- shortens sleep-onset time and improves subjective sleep quality;
- reduces subjective anxiety and fatigue.
The effect is attributed to the triterpenoid fraction. It is one of the few directions where human clinical data exist and are broadly consistent.
Metabolism (type 2 diabetes, lipid profile)
In several studies in patients with type 2 diabetes and metabolic syndrome, reishi intake (3–12 weeks) led to:
- a moderate reduction in fasting glucose;
- improved lipid profile (lower LDL, triglycerides).
The effect size is small, samples in the dozens. Large RCTs are still lacking.
Cardiovascular effects
A moderate antihypertensive action (on average 5–10 mmHg) and an antiplatelet action have been described. These data require cautious interpretation: reishi can potentiate anticoagulants, which matters with concomitant therapy.
Where the evidence is weak
- Neuroprotection. Most of the work is in animals. Clinical data are isolated.
- Antiviral activity. Laboratory effects exist, but human RCTs for specific viral infections are insufficient.
- Antioxidant action in humans. Effects are pronounced in cell models, but in humans oxidative-stress markers change modestly and not in all studies.
- Long-term safety. In short-term studies (up to 12 weeks) side effects are rare (occasionally mild GI discomfort, dry mouth). Long-term RCTs are few.
Commercial product quality
According to independent laboratory checks (similar to the situation described in Mushroom supplements in Italy), the market contains:
- fruiting body substituted with mycelium-on-grain;
- β-glucan and triterpenoid content below the declared levels;
- heavy-metal contamination (especially in wild-harvested material).
Practically, this means clinical results obtained with standardized extracts cannot automatically be transferred to an arbitrary commercial supplement.
What is important to keep in mind
- Reishi is a dietary supplement. Not registered as a medicine in either the EU or Russia. It is included in the pharmacopoeias of several Asian countries as a medicinal plant.
- Interactions. Reishi can potentiate anticoagulants, antihypertensives and hypoglycemic drugs — a documented effect, not a formality.
- Standardization is critical. Comparing products without stated β-glucan and triterpenoid content is invalid.
- It is not a panacea. The most reproducible clinical effects are adjuvant support during cancer therapy and improved sleep and quality of life. The other claimed effects require larger RCTs.
Related materials
- Species card: Reishi
- Catalog: Mushroom catalog
- Mechanisms: Beta-glucans and immunity, topic Mushrooms and immunity
- Use: Mushroom supplements in integrative oncology
- Quality: Mushroom supplements in Italy
- Other wood-decay fungi: Chaga, Trametes, Lion's mane, Agarikon
- Sources