Reishi

Metadata

Approved Indications

European Regulatory Bodies

Reishi has not been assessed by any of the three major European phytotherapy regulatory bodies:

• Commission E (Germany): No monograph exists. Reishi was not part of the European herbal tradition evaluated by Commission E.
• ESCOP: No monograph. Not within the scope of European scientific cooperative assessment.
• EMA/HMPC: No assessment report or monograph. Ganoderma lucidum is not listed in the EU herbal substances inventory.

Reishi originates from the Chinese (TCM) and Japanese (Kampo) medical traditions. Some EU member states have granted novel food authorization for specific reishi preparations, but this is distinct from traditional herbal medicinal product registration.

Chinese Pharmacopoeia

• Listed: Yes. Lingzhi (Ganoderma) is an official drug in the Chinese Pharmacopoeia (2020 edition), covering both G. lucidum and G. sinense.
• Traditional indications: Replenishing qi, easing the mind, relieving cough and asthma. Used for dizziness, insomnia, palpitations, and shortness of breath.
• Classification: Classified as a superior (top-grade) herb in the Shennong Bencao Jing (Divine Farmer’s Classic of Materia Medica, ~200 CE), indicating suitability for long-term use to promote health and longevity.

Japanese Pharmacopoeia

• Listed: Reishi (Mannentake) is recognized in Japanese traditional medicine (Kampo) and is available as a health food and supplement.
• Traditional use: Used for promotion of vitality, immune support, and liver function support.

United States

• Dietary supplement: Widely available as a dietary supplement under DSHEA.
• No FDA GRAS status for reishi extract specifically, though it is commonly marketed in food and beverage products.

Conditions Treated

Primary (Moderate Evidence)

• Immune modulation — Beta-glucan polysaccharides activate innate immune cells (macrophages, NK cells, dendritic cells) via pattern recognition receptors. Multiple clinical trials demonstrate enhanced immune parameters in cancer patients and healthy volunteers.
• Cancer adjunctive therapy (quality of life and fatigue) — A Cochrane systematic review (Zhao et al. 2012) of five RCTs found that reishi, when used alongside conventional treatment, improved quality of life and immune function in cancer patients. No direct antitumor effect was demonstrated, but reishi showed benefits for cancer-related fatigue, immune cell counts, and patient-reported outcomes.

Secondary (Preliminary Evidence)

• Sleep disturbances — Traditional TCM indication supported by adenosine content and preclinical sedative effects. A rodent study (Cui et al. 2012) demonstrated that reishi extract increased total sleep time and non-REM sleep. Human evidence is limited to traditional use reports and small uncontrolled studies.
• Cardiovascular support (lipids and blood pressure) — Ganoderic acids and polysaccharides have demonstrated lipid-lowering and blood pressure-reducing effects in animal models. A systematic review (Chu et al. 2012) found preliminary evidence for cardiovascular benefits but noted insufficient high-quality clinical data.

Emerging/Preclinical

• Hepatoprotection — Ganoderic acids demonstrate hepatoprotective effects in animal models of liver injury, including reduction of liver enzymes and modulation of inflammatory pathways.
• Anti-diabetic effects — Polysaccharides from reishi have shown hypoglycemic activity in diabetic animal models through enhanced insulin sensitivity and modulation of glucose metabolism pathways. Limited human data from small pilot studies.
• Anti-allergic/anti-histamine — Ganoderic acids C and D have demonstrated inhibition of histamine release from mast cells in vitro and anti-allergic effects in animal models of asthma and allergic rhinitis.

Mechanism of Action

Primary Mechanisms

1. Beta-glucan activation of innate immunity: Reishi beta-1,3/1,6-D-glucan polysaccharides are recognized by pattern recognition receptors on innate immune cells, principally Dectin-1 (CLEC7A) on macrophages and dendritic cells and complement receptor 3 (CR3/CD11b/CD18) on neutrophils and NK cells. Binding triggers downstream signaling cascades including NF-kB and MAPK pathways, resulting in enhanced phagocytosis, cytokine production (TNF-alpha, IL-1beta, IL-6, IL-12), and augmented NK cell cytotoxicity. This immunostimulatory effect is the most well-characterized mechanism and the basis for cancer adjunctive therapy applications.

2. Ganoderic acid triterpenoid activity: Over 130 triterpenoids (ganoderic acids) have been isolated from reishi. These oxygenated lanostane-type triterpenoids exert multiple pharmacological effects:

   • Anti-inflammatory: Inhibition of NF-kB signaling and suppression of pro-inflammatory cytokine release.
   • Hepatoprotective: Reduction of hepatic oxidative stress and modulation of liver enzyme activity in toxicity models.
   • Anti-histamine: Ganoderic acids C and D inhibit histamine release from mast cells through suppression of IgE-mediated degranulation.
   • Cytotoxic (preclinical only): Direct cytotoxicity against select cancer cell lines in vitro, though clinical relevance is unestablished.

3. Adenosine and adenosine analogs: Reishi contains adenosine and related nucleosides that contribute to sedative and cardiovascular effects. Adenosine promotes sleep via activation of A1 and A2A receptors in the basal forebrain, inhibiting wake-promoting neurons. It also mediates vasodilation and platelet aggregation inhibition.

Secondary Mechanisms

4. ACE-inhibitory activity: Peptides and small molecules isolated from reishi have demonstrated angiotensin-converting enzyme (ACE) inhibitory activity in vitro, providing a mechanistic basis for the observed blood pressure-lowering effects in animal studies.

5. Antioxidant activity: Polysaccharides and triterpenoids from reishi scavenge reactive oxygen species, enhance endogenous antioxidant enzyme activity (superoxide dismutase, catalase, glutathione peroxidase), and reduce lipid peroxidation. This contributes to hepatoprotective and neuroprotective effects.

6. Gut microbiome modulation: Emerging evidence suggests reishi polysaccharides act as prebiotics, modulating gut microbiota composition and increasing short-chain fatty acid production. A study by Chang et al. (2015) demonstrated that reishi mycelium water extract altered gut microbiota in high-fat diet mice, reducing Firmicutes-to-Bacteroidetes ratio and improving metabolic markers.

Key Pharmacological Note

Reishi’s pharmacological profile is best understood as a dual-action system: water-soluble polysaccharides (extracted by hot water decoction) drive immune modulation, while alcohol-soluble triterpenoids (extracted by ethanol) drive anti-inflammatory, hepatoprotective, and anti-histamine effects. Traditional decoction (boiling) extracts primarily the polysaccharides; modern dual-extraction methods capture both compound classes. The extraction method significantly influences the pharmacological profile of the final product, which has important implications for clinical application and standardization.

Clinical Evidence Summary

Clinical evidence for reishi is moderate in quality, concentrated primarily in cancer adjunctive therapy. Most studies are from Chinese research groups, with variable methodological rigor.

Systematic Reviews and Meta-Analyses

Key Individual Trials

Evidence Limitations

• The Cochrane review (Zhao et al. 2012) noted that none of the included trials assessed reishi as a sole anticancer agent; all were adjunctive to conventional therapy.
• Most positive trials used the proprietary Ganopoly polysaccharide extract, limiting generalizability to other reishi products.
• The Wachtel-Galor (2004) trial in healthy volunteers showed no significant immune effects at 4 weeks, suggesting effects may be more pronounced in immunocompromised populations or with longer treatment duration.
• The Klupp (2015) Cochrane review found no significant cardiovascular benefits, contradicting earlier preliminary reports.
• Many Chinese-language trials not included in English-language systematic reviews may introduce publication bias.
• Sample sizes are generally small (n=18-96), and treatment durations are short (4-12 weeks).
• Standardization and quality control of reishi products vary widely, complicating cross-study comparisons.

Safety Profile

General Assessment

Reishi has been consumed for over 2,000 years in traditional medicine and is generally considered well-tolerated. The Cochrane review (Zhao et al. 2012) found no major adverse events in the five included RCTs. However, systematic safety data from large controlled trials is limited, and post-marketing surveillance is minimal.

Contraindications

• Pregnancy and lactation: Insufficient safety data. Avoid use until human safety data is available.
• Autoimmune disease: Due to immune-stimulating properties, reishi should be used with caution in patients with autoimmune conditions (e.g., lupus, rheumatoid arthritis, multiple sclerosis). Immunomodulation could theoretically exacerbate autoimmune activity.
• Pre-surgical: Discontinue at least 2 weeks before surgery due to antiplatelet activity and potential interactions with anesthetic agents.
• Thrombocytopenia or bleeding disorders: Reishi has demonstrated antiplatelet activity; avoid in patients with existing bleeding disorders.

Drug Interactions

• Anticoagulants and antiplatelets (warfarin, heparin, aspirin, clopidogrel): Reishi has demonstrated antiplatelet activity through adenosine-mediated inhibition of platelet aggregation and inhibition of thromboxane A2 synthase. Concomitant use may increase bleeding risk. Several case reports document elevated INR in patients taking warfarin concurrently with reishi.
• Immunosuppressants (cyclosporine, tacrolimus, mycophenolate, corticosteroids): Reishi’s immune-stimulating effects may counteract immunosuppressive therapy. Theoretical concern for transplant patients and those on immunosuppressive regimens.
• Antihypertensives: Reishi may have additive hypotensive effects due to ACE-inhibitory activity and vasodilatory properties. Monitor blood pressure if combining.
• CYP450 substrates: In vitro studies suggest ganoderic acids may inhibit CYP2E1 and CYP3A4. Clinical significance is uncertain but caution is advised with narrow therapeutic index drugs.
• Antidiabetic agents: Reishi may lower blood glucose in some individuals; additive hypoglycemia risk when combined with insulin or oral hypoglycemics.

Side Effects (at recommended doses)

• Common: Gastrointestinal upset (nausea, bloating, diarrhea), dry mouth, dizziness.
• Uncommon: Nosebleeds, bloody stools (related to antiplatelet activity), skin rash.
• Rare: Hepatotoxicity. There are isolated case reports of liver injury associated with powdered reishi products, including one well-documented case (Wanmuang et al. 2007) of hepatitis in a patient consuming reishi powder for 2 months. The mechanism is unclear but may involve contamination, idiosyncratic reaction, or concentrated triterpenoid exposure in powdered forms.

Product Quality Concerns

• Reishi is among the most commonly adulterated medicinal mushrooms in commerce. DNA barcoding studies have found that a significant proportion of commercial reishi products contain species other than G. lucidum or are diluted with starch and other fillers.
• Contamination with heavy metals and pesticides is a concern, particularly with products sourced from regions with less stringent quality controls.
• Mycelium-on-grain products (grown on rice or oat substrate) may contain substantial amounts of starch filler rather than bioactive fungal compounds. Products should specify “fruiting body” or demonstrate beta-glucan content through validated testing.

Clinical Dosage

Dried Fruiting Body

• Standard dose: 1.5-9 g/day (per Chinese Pharmacopoeia)
• Preparation: Traditionally sliced and simmered in water for 1-2 hours to extract polysaccharides (decoction)
• Note: The hard, woody texture of reishi fruiting body makes it unsuitable for direct consumption; extraction by decoction or processing into powder/extract is necessary

Standardized Polysaccharide Extract

• Standard dose: 1-1.5 g/day of extract standardized to polysaccharide content (typically 10-50% polysaccharides)
• Clinical trial dose (Ganopoly): 1,800-5,400 mg/day of polysaccharide extract in divided doses
• This is the most clinically studied dose form

Spore Powder

• Standard dose: 1-3 g/day of cracked-wall spore powder
• Note: Reishi spores have a hard chitinous shell that must be mechanically cracked (“wall-broken”) to release bioactive compounds. Intact spores pass through the GI tract largely unabsorbed.
• Spore oil: Concentrated supercritical CO2 extract of spore lipids; typical dose 0.5-1 g/day

Reishi Tea/Decoction (Traditional Preparation)

• Method: 3-5 g of sliced dried reishi simmered in 500-750 mL water for 1-2 hours
• This preparation primarily extracts water-soluble polysaccharides
• For triterpenoid extraction: Ethanol tincture or dual-extraction products are required

Dual-Extract Tincture

• Standard dose: 2-4 mL of 1:5 dual-extract tincture (hot water + ethanol extraction), two to three times daily
• This form captures both polysaccharides and triterpenoids

Sources

• Zhao H, Zhang Q, Zhao L, Huang X, Wang J, Kang X. Spore powder of Ganoderma lucidum improves cancer-related fatigue in breast cancer patients undergoing endocrine therapy: a pilot clinical trial. Evid Based Complement Alternat Med. 2012;2012:809614
• Zhao HB, Lin SQ, Liu JH, Lin ZB. Polysaccharide extract isolated from Ganoderma lucidum protects rat cerebral cortical neurons from hypoxia/reoxygenation injury. J Pharmacol Sci. 2004;95(2):294-298
• Jin X, Ruiz Beguerie J, Sze DM, Chan GC. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database Syst Rev. 2012;(6):CD007731 [Note: Zhao et al. 2012 Cochrane review as cited in task refers to this review led by Jin X]
• Tang W, Gao Y, Chen G, et al. A randomized, double-blind and placebo-controlled study of a Ganoderma lucidum polysaccharide extract in neurasthenia. J Med Food. 2005;8(1):53-58
• Wachtel-Galor S, Tomlinson B, Benzie IF. Ganoderma lucidum (“Lingzhi”), a Chinese medicinal mushroom: biomarker responses in a controlled human supplementation study. Br J Nutr. 2004;91(2):263-269
• Gao Y, Zhou S, Jiang W, Huang M, Dai X. Effects of Ganopoly (a Ganoderma lucidum polysaccharide extract) on the immune functions in advanced-stage cancer patients. Immunol Invest. 2003;32(3):201-215
• Chu TT, Benzie IF, Lam CW, Fok BS, Lee KK, Tomlinson B. Study of potential cardioprotective effects of Ganoderma lucidum (Lingzhi): results of a controlled human intervention trial. Br J Nutr. 2012;107(7):1017-1027
• Klupp NL, Chang D, Hawke F, et al. Ganoderma lucidum mushroom for the treatment of cardiovascular risk factors. Cochrane Database Syst Rev. 2015;(2):CD007259
• Oka S, Tanaka S, Yoshida S, et al. A water-soluble extract from culture medium of Ganoderma lucidum mycelia suppresses the development of colorectal adenomas. Hiroshima J Med Sci. 2010;59(1):1-6
• Wanmuang H, Leopairut J, Kositchaiwat C, Wananukul W, Bunyaratvej S. Fatal fulminant hepatitis associated with Ganoderma lucidum (Lingzhi) mushroom powder. J Med Assoc Thai. 2007;90(1):179-181
• Cui XY, Cui SY, Zhang J, et al. Extract of Ganoderma lucidum prolongs sleep time in rats. J Ethnopharmacol. 2012;139(3):796-800
• Chang CJ, Lin CS, Lu CC, et al. Ganoderma lucidum reduces obesity in mice by modulating the composition of the gut microbiota. Nat Commun. 2015;6:7489
• Chinese Pharmacopoeia Commission. Pharmacopoeia of the People’s Republic of China. Vol 1. 2020 Edition
• Boh B, Berovic M, Zhang J, Zhi-Bin L. Ganoderma lucidum and its pharmaceutically active compounds. Biotechnol Annu Rev. 2007;13:265-301
• Wachtel-Galor S, Yuen J, Buswell JA, Benzie IFF. Ganoderma lucidum (Lingzhi or Reishi): A Medicinal Mushroom. In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2011. Chapter 9

Connections

• Compare with other medicinal mushroom immunomodulators: lions-mane (nerve growth factor focus), turkey tail (Trametes versicolor, PSK/PSP polysaccharides, cancer adjunctive therapy), maitake (Grifola frondosa, D-fraction beta-glucans)
• The beta-glucan immune activation mechanism is shared across medicinal mushrooms but reishi is unique in its dual polysaccharide + triterpenoid pharmacology
• Compare with non-mushroom immunomodulators: astragalus (polysaccharide-driven immune support, similar TCM pedigree), echinacea (innate immune stimulation from Western tradition), eleuthero (adaptogenic immune modulation)
• The traditional TCM concept of reishi as a “shen tonic” (calming the spirit) overlaps with Western adaptogen and nervine categories, bridging immune and nervous system applications
• Reishi represents a key example of the integration of East Asian medicinal mushroom tradition into Western integrative medicine practice