Reishi (Ganoderma lucidum)
A functional mushroom with more than 2,000 years of history in Chinese and Japanese medicine, studied for its immune-modulating effects — human clinical evidence, however, remains modest and partly contradictory.
Number of studies
2
Safety
Requires caution
Time to effects
Subjective effects (well-being, sleep) are sometimes reported after 2–4 weeks; changes in immune parameters were observed in studies after 8–12 weeks of regular use.
Monthly cost
ok. 40–90 zł/miesiąc
Price in Poland
40–90 zł za 90–100 kapsułek ekstraktu owocnika (miesiąc stosowania) lub 35–60 zł za 100 g proszku
Who it's for
Ekstrakty dual-extract (woda + alkohol) są zwykle o 30–50% droższe, ale mają szerszy profil wyciągniętych związków (triterpeny + polisacharydy) niż tanie ekstrakty czysto wodne.
Indicative prices for the Polish market — we don't point to specific retailers; the real price depends on the manufacturer, form and place of purchase.
Table of contents
TL;DR
A functional mushroom with more than 2,000 years of history in Chinese and Japanese medicine, studied for its immune-modulating effects — human clinical evidence, however, remains modest and partly contradictory.
- →Documented in a small RCT: increased T-cell count (CD3+, CD4+, CD8+) and NK-cell activity in healthy adults
- →Preliminary data suggesting reduced fatigue and improved well-being with long-term use
- →Traditionally used to support sleep and reduce perceived stress
| Latin name | Ganoderma lucidum |
|---|---|
| Family | Ganodermataceae |
| Active compounds | Beta-glucans, ganoderic acids (triterpenes) |
| Form | Fruiting-body extract — capsules, powder or dual-extract tincture |
| Level of evidence | Preliminary — mechanism well studied, hard endpoints in humans poorly confirmed |
| Interactions | Anticoagulant, immunosuppressive, blood-pressure-lowering drugs |
| Status | Over-the-counter dietary supplement |
Understand
Overview
Reishi (Ganoderma lucidum), known in Japan as reishi and in China as lingzhi ('mushroom of immortality'), is a bracket fungus from the Ganodermataceae family, growing on dying or dead deciduous tree trunks. Its distinctive shiny, seemingly lacquered cap owes its name to the triterpenes that form a waxy sheen on the surface. In traditional Chinese medicine it's been used for thousands of years as a 'qi-strengthening' agent, supporting longevity, sleep and immunity.
Today reishi is one of the best-documented functional mushrooms in terms of mechanism of action, but hard endpoints in humans — improvement in real health outcomes, not just blood markers — remain less well confirmed than its market popularity would suggest.
In practice, reishi may help mainly healthy people looking for gentle, long-term immune support who are willing to use the mushroom cyclically for many weeks — that's the group pointed to by data on increased T-cell counts and NK-cell activity from a study in healthy adults. There's no basis, however, for reaching for reishi with the goal of lowering blood sugar or cholesterol — the largest and best-designed study to date, conducted in people with metabolic syndrome, didn't confirm that effect. People with liver disease, clotting disorders, an upcoming surgical procedure, or who are pregnant or breastfeeding should avoid it or consult a doctor before use.
Where it's found
Reishi occurs rarely in nature — it grows as a parasite or saprotroph on dying and dead deciduous tree trunks (mainly oaks and plums) in the warm, humid climates of East Asia (China, Japan, Korea), with isolated occurrences also recorded in Europe, including Poland. Because of the low availability of wild fruiting bodies, nearly all commercial reishi production today comes from controlled cultivation on wood or grain substrates.
History of use
In Chinese herbal treatises such as the 'Shennong Bencao Jing' (c. 1st century CE), reishi holds a place in the highest class of 'immortality' herbs. Because of the rarity of wild fruiting bodies, for centuries it was a luxury good available almost exclusively to the imperial court and aristocracy. It was only the development of wood-based cultivation methods in Japan and China in the 1970s that made reishi widely available beyond elite circles.
Mechanism of action
Reishi contains two main groups of bioactive compounds with different action profiles: polysaccharides (including beta-glucans), water-soluble and studied mainly for their immune-modulating effect through activation of macrophages, NK cells and T cells, and triterpenes (ganoderic acids), fat-soluble, credited with anti-inflammatory, antioxidant and potentially liver-protective effects. Both mechanisms have been confirmed mainly in in vitro and animal studies; in humans, the immunomodulatory effect has been shown in a few small studies measuring blood markers, while hard endpoints (e.g. reduction in infections, improvement in metabolic parameters) haven't been unambiguously confirmed in larger randomized trials.
At the receptor level, beta-glucans from reishi bind to the Dectin-1 receptor and TLR2/TLR4 receptors on the surface of macrophages and dendritic cells, triggering the NF-κB cascade and cytokine secretion (IL-2, IFN-γ, TNF-α) — this explains the increase in T-cell count and NK-cell activity observed in studies. Ganoderic acids (triterpenes) act through a different route: they inhibit the cyclooxygenase (COX) and 5-lipoxygenase enzymes involved in prostaglandin and leukotriene synthesis.
Binding to innate immunity receptors
Beta-glucans bind to Dectin-1 and TLR2/4 on macrophages and dendritic cells.
Activation of the NF-κB cascade
Triggering this pathway leads to secretion of immunostimulatory cytokines (IL-2, IFN-γ).
Stimulation of T cells and NK cells
Increase in CD3+/CD4+/CD8+ counts and NK cytotoxic activity, confirmed in an RCT in healthy adults.
Parallel action of triterpenes
Ganoderic acids inhibit COX and 5-LOX, limiting synthesis of inflammatory mediators independently of the polysaccharide pathway.
Antioxidant and hepatoprotective effect
Neutralization of free radicals and potential protection of liver cells observed in preclinical models.
Evidence: early-stage — based on 2 studies in this database.
Benefits
Common myths
MythReishi cures cancer in humans.
FactAnti-cancer activity has been shown in in vitro and animal studies and as an adjunct therapy in some oncology studies from Asia, but reishi isn't a standalone cancer treatment and doesn't replace oncological therapy.
MythSince it's a natural mushroom, it can be safely used without time or dose limits.
FactCases of liver damage have been described with long-term, high-dose use of reishi spore powder — 'natural' doesn't mean risk-free.
Forms & variants
Reishi (Ganoderma lucidum) comes in several forms that differ in bioavailability and use case — the form you pick genuinely matters for how effective the supplementation is.
Fruiting-body extract in capsules
A standardized water-alcohol (dual-extract) extract of the fruiting body, closest to the compound profile studied in RCTs.
Best for: People wanting convenient, predictable dosing without the taste
Fruiting-body powder
Dried and ground fruiting body or its water extract in powder form, to dissolve in a drink.
Best for: People who prefer adding it to coffee/tea or a smoothie and can accept the bitter taste
Dual-extract tincture
Alcohol-water extraction preserving both triterpenes and polysaccharides.
Best for: People seeking the broadest spectrum of extracted compounds, accepting a higher price
Practice
Frequently asked questions
The largest randomized study to date (84 people with metabolic syndrome, 16 weeks) found no significant effect of reishi on HbA1c, fasting glucose or the lipid panel. Earlier, smaller and less rigorous studies suggested some benefits, but the best-designed study didn't confirm this.
For most people, yes, but isolated cases of liver damage have been reported with long-term use of high doses, especially spore powder. People with liver disease should exercise caution and consult a doctor.
In clinical studies, measurable changes in immune parameters were observed after 8–12 weeks of daily use. Subjective effects are sometimes reported earlier, but this isn't data confirmed by controlled studies.
Dosage & timing
Typical dose
1,000–3,000 mg of fruiting-body extract per day (clinical studies used doses of up to 3 g/day)
Form
Fruiting-body extract (not spores) standardized to beta-glucans and triterpenes — capsules, powder or dual-extract tincture
Dosing is informational and reflects the ranges used in the cited studies — it does not replace consulting a doctor or pharmacist.
Best times to take it
- With a meal containing fat — improves triterpene absorption
- In the evening, if the goal is to support relaxation and sleep
What to combine with
Good combinations
Lion's Mane — A common combination in mushroom 'stacks' — complementary profiles (cognition + relaxation/immunity), no known interactions
Cordyceps militaris — A popular pairing in multi-ingredient supplements; studied together in an RCT without significant adverse effects
Safety
Side effects & contraindications
Possible side effects
Gastrointestinal complaints (dry mouth, nausea, diarrhea) at higher doses
Rarely: allergic reactions in people allergic to mushrooms
Sporadic case reports of hepatotoxicity with long-term use of high doses of spore powder
Contraindications
Liver disease — caution due to case reports of liver damage with chronic, high-dose use
Clotting disorders and planned surgical procedures — discontinue at least 2 weeks before surgery
Pregnancy and breastfeeding — insufficient safety data
Mushroom allergy
Interactions
Anticoagulant/antiplatelet drugs (e.g. warfarin, aspirin) — increased bleeding risk
Immunosuppressive drugs — theoretical interaction due to reishi's immunostimulatory effect
Blood-pressure-lowering drugs — reishi may enhance the blood-pressure-lowering effect
Is it worth taking?
Who it's for
- People seeking gentle, long-term immune and relaxation support, willing to use the mushroom cyclically for weeks/months
- People interested in traditional Chinese/Japanese medicine, accepting that human clinical evidence is currently modest
Not for
- Liver disease — caution due to case reports of liver damage with chronic, high-dose use
- Clotting disorders and planned surgical procedures — discontinue at least 2 weeks before surgery
- Pregnancy and breastfeeding — insufficient safety data
- Mushroom allergy
Evidence
Worth knowing
The Chinese name 'lingzhi' literally means 'mushroom of immortality/divine power' — a symbol of longevity in Chinese art and medicine for millennia.
The characteristic sheen of the cap results from a layer of triterpenes on the fruiting body's surface, hence the Latin name 'lucidum' (shiny).
Studies
In an 84-day, double-blind, placebo-controlled study, beta-glucan from reishi increased T-cell counts, improved the CD4/CD8 ratio and raised NK-cell activity in healthy adults.
Chen S.N. et al., Foods, 2023
A double-blind, randomised, placebo-controlled trial of Ganoderma lucidum for the treatment of cardiovascular risk factors of metabolic syndrome
Moderate evidenceKlupp N.L., Kiat H., Bensoussan A., Steiner G.Z., Chang D.H. · Scientific Reports · 2016
A 16-week RCT in 84 people with type 2 diabetes and metabolic syndrome found no significant effect of Ganoderma lucidum extract on HbA1c, fasting glucose, or other cardiometabolic parameters — an important counterpoint to reishi's marketing claims.
View studyEvaluation of Immune Modulation by β-1,3;1,6 D-Glucan Derived from Ganoderma lucidum in Healthy Adult Volunteers, A Randomized Controlled Trial
Early-stage evidenceChen S.N., Nan F.H., Liu M.W., Yang M.F., Chang Y.C., Chen S. · Foods · 2023
An 84-day, double-blind RCT in healthy adults showed that beta-glucan from reishi increased T-cell counts, improved the CD4/CD8 ratio, raised NK-cell activity and IgA levels compared with placebo.
View studySources & bibliography
Citations are illustrative for this demo version and require full bibliographic verification by the editorial team before production publication.
Compare with similar entries
About the authors of this entry
Author
Michał NowakClinical Dietitian
Michał specializes in metabolic nutrition, intermittent fasting and sports supplementation.
61 publications on this site
Medical review
dr Piotr ZielińskiEndocrinologist
Piotr reviews content on hormones, metabolic health and supplement pharmacology.
131 publications on this site
Related entries
4.4Lion's Mane
A functional mushroom studied for its effect on nerve growth factor (NGF) and cognitive function — human evidence is still preliminary.
4.1Cordyceps militaris
A laboratory-cultivated functional mushroom — this is the species behind almost every 'cordyceps' supplement sold today. High, stable cordycepin content, but evidence for improved physical performance in humans is still mixed.
4.0Siberian Chaga (Inonotus obliquus)
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4.5Turkey Tail
The mushroom behind PSK and PSP — the only fungal polysaccharides registered in Japan as drugs supporting chemotherapy. Among the most solid clinical evidence of any functional mushroom, but this is NOT a standalone cancer therapy.
4.3Shiitake
A culinary-functional mushroom rich in lentinan and beta-glucans, studied clinically for immune modulation and lipid profile — one of the best-researched functional mushrooms on the market.
4.3Oyster Mushroom (Pleurotus ostreatus)
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4.1Almond Mushroom (Agaricus blazei)
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Comments (2)
- KW
Kasia W. 2 weeks ago
Very clearly explained, especially the interactions section — I hadn't seen it laid out this well anywhere else.
- MT
Marek T. a month ago
Are you planning to update this with the newest study from this year? I saw an interesting meta-analysis.