What Does the Clinical Evidence Say About Reishi Mushroom Extract?

Reishi (Ganoderma lucidum) has been used in traditional Chinese medicine for over two thousand years. You may hear reishi claims all the time: boosts immunity, helps cancer patients, protects the liver and so on. In the last four decades, researchers have worked to figure out which traditional uses hold up under controlled conditions.

The challenge? Reishi is not one thing. It contains hundreds of bioactive compounds — polysaccharides, triterpenoids (including ganoderic acids), phenolic compounds, and peptides — and different extraction methods pull out different ones. A 2021 comprehensive review in Phytotherapy Research analyzed the full scope of reishi clinical research, noting that the number of patents and clinical trials continues to grow year over year¹1. This makes the research messy but also creates opportunities for suppliers who understand the science behind their specifications. We went through the published human clinical trials and pulled out what the evidence supports. No marketing spin. Just what the science says, and what it does not.

A Quick Look at the Research Timeline

Clinical trials on reishi started in Japan in the 1980s, driven by interest in polysaccharides and triterpenes. By the early 2000s, research had spread to China, Korea, and the United States. A 2024 comprehensive review in the Journal of  Traditional and Complementary Medicine catalogued the chemical constituents, pharmacological effects, and clinical data for reishi, concluding that the evidence base is substantial but uneven across different health claims²2.

As of 2025, more than 150 human clinical trials involving reishi extracts have been registered or published, with the largest cluster in oncology — specifically, using reishi alongside chemotherapy to improve quality of life³ [3].

A 2025 clinical evidence overview published in Integrative Cancer Therapies (SAGE) reviewed the data across oncology, cardiovascular conditions, antioxidant status, and immune function, concluding that “the body of clinical evidence supports a beneficial role for reishi in cancer supportive care”.

The benefits have been clinically supported

Immune Function — The Most Studied Benefit
Immune modulation has the strongest clinical support across multiple trial types, including the 2025 athletes meta-analysis. This is where the data is strongest. A 2025 systematic review and meta-analysis published in Frontiers in Nutrition examined eight randomized controlled trials (N=288) on fungal supplementation in athletes. The analysis found that Ganoderma lucidum extracts significantly elevated hemoglobin concentrations, with stronger effects observed for triterpenoid and polysaccharide extracts specifically.

Multiple studies also confirm that reishi modulates cytokine profiles — influencing both pro-inflammatory and anti-inflammatory markers — pointing to immune modulation rather than simple immune stimulation. A 2025 specialized review on reishi’s effects on natural killer (NK) cells traced the mechanistic evidence from traditional use through to modern immunotherapy applications⁴ [5].

Reishi modulates immunity rather than just “boosting” it — a more accurate and defensible claim. Reishi polysaccharides, particularly beta-glucans, interact with immune cells in measurable ways.

Cancer Care — Adjuvant Therapy Evidence
The use of cancer adjuvants improves quality of life — as confirmed by the Cochrane review⁵ [6] and a 2024 patient survey⁶7— but the survival benefits remain unproven. Reishi extract is not a cancer treatment. The evidence supports use alongside conventional therapy, not instead of it.

The landmark Cochrane systematic review by Jin and colleagues evaluated five randomized controlled trials with 373 cancer patients. The findings: patients receiving reishi alongside chemotherapy were more likely to respond to their cancer treatment compared to those receiving chemotherapy alone. Quality of life measures also favored the reishi group.

A 2024 cross-sectional survey of Chinese cancer patients using reishi products, published in the Journal of Herbal Medicine (Elsevier), documented the types of symptom improvements and adverse events patients reported after taking reishi. The findings reinforced the supportive care role, as patients reported improvements in treatment-related symptoms; however, the authors cautioned that larger, controlled studies are needed for definitive conclusions.

But here is the honest limitation: survival benefits were inconsistent across trials. Some studies trended toward longer survival; others showed no statistical difference. The honest message: reishi helps patients feel better during treatment. Whether it extends life is still unclear.

Heart Health and Metabolic Effects
Metabolic effects are plausible based on the 2016 Scientific Reports trial but need larger confirmatory studies. A well-cited 2016 double-blind, randomized, placebo-controlled trial published in Scientific Reports (Nature) studied 84 participants with type 2 diabetes and metabolic syndrome⁷ [8]. Participants were randomized to Ganoderma lucidum, Ganoderma lucidum with Cordyceps sinensis, or placebo.

The trial examined cardiovascular risk factors, including blood pressure, blood glucose, and lipid profiles over 16 weeks. While the study’s primary focus was glycemic control, it represents one of the better-designed metabolic trials for reishi.

A 2025 meta-analysis in Food Science & Nutrition (Wiley) assessed the impact of reishi supplementation across a dose range of 200–11,200 mg/day, lasting 1–24 weeks, on various health-related outcomes including metabolic markers⁸ [9]. The dose-response relationship underscores a critical point for suppliers: the extract specifications and dosage used directly determine the clinical outcome.

Liver Protection — The Hepatoprotective Evidence
Liver protection is a traditional use with growing modern support. A 2023 review in Nutrients (MDPI) comprehensively catalogued the hepatoprotective mechanisms of Ganoderma lucidum, covering non-alcoholic fatty liver disease (NAFLD), alcohol-induced liver injury, hepatic cancer, and hepatitis⁹ [10].

The standout clinical study: a Phase I/II double-blind, randomized, multicenter trial evaluated a standardized reishi extract (Ganopoly) in 90 patients with chronic hepatitis B¹⁰ [11]. The study assessed both safety and liver enzyme normalization, providing one of the stronger pieces of clinical evidence for reishi’s hepatoprotective effects.

The active compounds driving this effect: ganoderic acids and polysaccharides, which demonstrate anti-inflammatory and antioxidant activity in liver tissue. Extract specification matters directly here — meaningful triterpene content is the prerequisite for any hepatoprotective claim.

Fighting Fatigue — Energy and Quality of Life
The fatigue data comes principally from cancer supportive care studies. The 2024 Chinese cancer patient survey noted that fatigue reduction was among the most commonly reported benefits by patients using reishi alongside treatment¹¹ [7].

The Cochrane review similarly documented quality-of-life improvements across multiple cancer trials. The mechanism is thought to involve reduced systemic inflammation and improved cellular energy metabolism, though the precise pathway is still being studied. Importantly, this is not a stimulant effect — the benefit builds over weeks rather than hours, differentiating it from caffeine or other acute energy boosters.

Safety — Side Effects and Drug Interactions

Reishi has a generally favorable short-term safety profile. A 2024 toxicological assessment published in Frontiers in Toxicology examined the subchronic oral toxicity and genotoxicity potential of Ganoderma lucidum, noting that despite the mushroom’s long history of use, formal toxicological data in published literature remains limited¹² [12].

From clinical trials, the most commonly reported side effects include mild digestive discomfort, nausea, and loose stools. These appear to affect a minority of users and are typically dose-dependent.

A 2024 study in Frontiers in Pharmacology found that triterpenoids from Ganoderma lucidum displayed broad inhibitory effects on CYP enzymes, which may induce potential drug-drug interactions¹³ [13]. This is relevant for anyone taking medications metabolized through the CYP pathway.
Anticoagulant/antiplatelet effects: Reishi may enhance the effects of blood-thinning medications, which has been noted in case reports and pharmacological reviews. Long-term safety data beyond one year remain limited across the published literature.

Write in The Bottom

The 2021 Phytotherapy Research review noted persistent issues across the clinical research base: small sample sizes, inconsistent extract characterization, variable dosing, and — critically — poor reporting of extraction methods and standardization. When one study uses hot water extract at 1,500 mg/day and another uses a dual-extract at 5,400 mg/day, the results are not directly comparable.
The extract itself is the single biggest variable in reishi research. Studies use different raw materials, extraction solvents, standardization markers, and dosages, and the results reflect this variability. Hot water extraction primarily pulls out polysaccharides and beta-glucans, which support immune function. Ethanol extraction primarily pulls out triterpenoids, including ganoderic acids, which support liver and metabolic health. Dual-extraction captures both fractions, which is why most high-quality clinical studies use dual-extracts. This does not mean reishi is ineffective. It means claims must be matched to the specific extract type and dosage used in the relevant studies.

References
[1]Ganoderma lucidum (Reishi) an edible mushroom; a comprehensive and critical review of its pharmacological actions. Ahmad MF, et al. Phytotherapy Research. 2021. doi:10.1002/ptr.7215

[2] Recent progress in chemical constituents, pharmacology, pre-clinical and clinical studies of Ganoderma lucidum. Journal of Traditional and Complementary Medicine. 2024. doi:10.1016/j.jtcme.2023.11.001 →

[3] Clinical Evidence for the Use of Ganoderma lucidum Medicinal Mushroom. Integrative Cancer Therapies (SAGE). 2025. doi:10.1089/ict.2024.56835.luc

[4] Shu & Zhang. Effects of fungal supplementation on endurance, immune function, and performance: a systematic review and meta-analysis. Frontiers in Nutrition. 2025. doi:10.3389/fnut.2025.1670416

[5] Shallal & Razaq. Immunomodulatory Effects of Ganoderma lucidum on NK Cells: From Traditional Use to Modern Immunotherapy. 2025.

[6] Jin X, Ruiz Beguerie J, Sze DM, Chan GCF. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database of Systematic Reviews. 2016, Issue 4. Art. No.: CD007731.

[7] Symptom improvements and adverse effects with Reishi mushroom use among Chinese cancer patients: a cross-sectional survey. Journal of Herbal Medicine (Elsevier). 2024. doi:10.1016/j.hermed.2024.100935

[8] Klupp N, Kiat H, Bensoussan A, Steiner GZ, Chang DH. A double-blind, randomised, placebo-controlled trial of Ganoderma lucidum for the treatment of cardiovascular risk factors of metabolic syndrome. Scientific Reports. 2016;6:29540. doi:10.1038/srep29540  https://www.nature.com/articles/srep29540

[9] The Nutritional Significance of Ganoderma lucidum Supplementation. Food Science & Nutrition (Wiley). 2025. doi:10.1002/fsn3.70423

[10] Ganoderma lucidum: Novel Insight into Hepatoprotective Potential with Mechanisms of Action. Nutrients (MDPI). 2023. PMC10146730

[11] A phase I/II study of a Ganoderma lucidum extract (Ganopoly) in patients with chronic hepatitis B. International Journal of Medicinal Mushrooms. 2002.

[12] A toxicological assessment of Ganoderma lucidum: subchronic oral toxicity and genotoxicity. Frontiers in Toxicology. 2024. doi:10.3389/ftox.2024.1469348

[13] Triterpenoids from Ganoderma lucidum inhibit cytochrome P450 enzymes: implications for drug-drug interactions. Frontiers in Pharmacology. 2024. doi:10.3389/fphar.2024.1485209