What Is Reishi Good For? What the Trials Measured

Reishi (Ganoderma lucidum) has been tested in people for fatigue, immune markers, blood sugar, cholesterol and as an add-on in cancer care: in 132 patients with neurasthenia, 5.4 g a day of a reishi polysaccharide extract for eight weeks cut a fatigue score by 28% against 20% on placebo; in 398 people with type 2 diabetes or cardiovascular risk factors, 1.4 to 3 g a day for 12 to 16 weeks left HbA1c, cholesterol and weight unchanged; immune-cell counts rose in one healthy-volunteer trial and did not move in another; and the 2016 Cochrane review of reishi in cancer found five trials, none recording survival.^{1, 3, 5, 6, 7} No trial has measured sleep, memory or anxiety in otherwise healthy adults, and no mushroom holds an authorised health claim in Great Britain. Reishi evidence page of do mushroom supplements work?; side effects and the liver cases are in how you feel after taking reishi.

Sources checked on 29 October 2026.

What is reishi good for? What the trials measured

Reishi, lingzhi in China, is a woody bracket fungus taken as a decoction, powder or extract. Put the question to the trial record rather than a label and the answer is a short list: fatigue in two trials, immune-cell counts in one of two, physical fitness in one fibromyalgia trial, mood and quality of life in a breast-cancer pilot but not in a fibromyalgia trial, and nothing for blood sugar, cholesterol or weight. Each result carries its n, dose and duration.

What does reishi do for the brain?

No human trial has measured cognition, memory, neuroinflammation, brain plaque or mood as a primary outcome with reishi. The "neuroinflammation", adrenal and cortisol claims come from laboratory and animal work. In the 48-patient placebo-controlled fatigue pilot in breast cancer, anxiety and depression scores were lower on reishi at four weeks.⁴ In women with fibromyalgia, six weeks of 6 g a day did not change happiness, depression, life satisfaction or quality of life against placebo.¹⁰ Lion's mane has most of the placebo-controlled cognition trials, in older adults with mild impairment; reishi has none, so anyone taking it for anxiety or memory is outside what has been tested. The cortisol and stress trials that exist are of ashwagandha: does ashwagandha lower cortisol and stress, and what ashwagandha does for the brain.

Can reishi improve energy or fatigue?

Tang and colleagues randomised 132 Chinese patients with neurasthenia, persistent tiredness and poor concentration, to 1,800 mg of a reishi polysaccharide extract three times a day (5.4 g) or placebo for eight weeks. In the 123 assessed, the sense-of-fatigue score fell by 28.3% on reishi and 20.1% on placebo, and clinician-rated severity by 15.5% against 4.9%.³ A 2012 pilot randomised 48 women with breast cancer on endocrine therapy to 3 g a day of reishi spore powder or placebo for four weeks and recorded better fatigue scores and lower TNF-alpha and IL-6, two inflammation markers.⁴ In 64 women with fibromyalgia, 6 g a day of micro-milled reishi for six weeks improved aerobic endurance, flexibility and walking speed; a carob comparator did not.⁹ None of these groups was a healthy adult feeling tired, and the Great Britain register lists reishi's claim "stimulates the body in exhaustion" as non-authorised because "physical well-being" was judged not sufficiently defined.¹² An absent claim is a statement about the register, not proof of no effect.

Is reishi good for immunity? What the immune-marker trials measured

In an 84-day placebo-controlled trial of healthy adults aged 18 to 55, a daily reishi beta-1,3/1,6-glucan raised CD3+, CD4+ and CD8+ T-cell counts, natural-killer cell counts and activity, and serum IgA.⁵ In a four-week crossover trial of 18 healthy adults, 1.44 g a day of encapsulated reishi changed no immune, inflammation or DNA-damage marker.⁶ No reishi trial has counted infections against placebo. The register rejects every mushroom and yeast beta-glucan immune claim, so a marker change stays a marker change.¹²

Does reishi lower blood sugar or cholesterol?

The 2015 Cochrane review pooled five randomised trials, 398 participants with type 2 diabetes or cardiovascular risk factors, taking 1.4 to 3 g of reishi a day for 12 to 16 weeks. HbA1c changed by -0.10% (95% confidence interval -1.05 to 0.85), total cholesterol by -0.07 mmol/L (-0.57 to 0.42) and LDL by +0.02 mmol/L; body mass index did not change.⁷ The same group then randomised 84 people with type 2 diabetes and metabolic syndrome to 3 g a day of reishi, with or without cordyceps, or placebo for 16 weeks: HbA1c differed by 0.13% (-0.35 to 0.60), fasting glucose by 0.03 mmol/L, and adverse events were no more frequent than on placebo.⁸ A 2025 pooled analysis of 17 trials and 971 participants, at 200 to 11,200 mg a day for one to 24 weeks, found no change in cholesterol, glucose or blood pressure and rated the certainty very low; the one exception is a 12-week trial of 110 people with raised lipids taking reishi spore oil, a different preparation, which reported lower total cholesterol, triglycerides and LDL.^{13, 14}

Does reishi help you sleep?

Reishi's reputation as a sleep mushroom is traditional: PubMed holds no placebo-controlled trial of reishi and sleep in people without another condition, and none of the fatigue or fibromyalgia trials recorded sleep. Rat studies measured sleep time, the source of the "calming" descriptions.¹⁵

What does the Cochrane review say about reishi and cancer?

The 2016 Cochrane review found five randomised trials of reishi preparations in cancer patients. None recorded long-term survival; the outcomes were tumour response, natural-killer cell activity, T-cell subsets and a quality-of-life scale, the methodological quality was "generally unsatisfying", and only one trial reported adverse events.¹ A 2023 systematic review of 39 clinical studies of 12 mushroom preparations in cancer found survival signals for two other preparations and none for reishi.² Reishi is not a cancer treatment. Anyone on cancer treatment asks their oncology team first, because reishi is taken for its effect on immune markers and that combination has not been studied.

What form of reishi did the trials use?

Almost every trial used the fruiting body, the bracket itself: a polysaccharide extract for fatigue, micro-milled powder in fibromyalgia, encapsulated powder in the crossover trial, spore powder in the cancer pilot. A label stating the part used, the extraction (hot water for beta-glucans, alcohol for triterpenes) and a beta-glucan percentage tells you more than a 10:1 ratio, and quality varies: of 19 reishi supplements bought in the United States, only five matched their labels for triterpenes and polysaccharides.¹¹ Reishi mycelium, often grown on grain, is different in law: EU consultation documents record the fruiting body as eaten before May 1997 and so not a novel food, and dehydrated reishi mycelium powder as a novel food needing authorisation. Great Britain applies the same test, and the FSA's list of GB consultation outcomes names no reishi, so the GB position is inferred rather than ruled.¹⁶

What we don't know

No placebo-controlled trial has measured sleep, memory, anxiety or stress hormones in healthy adults, so reishi's best-known uses are untested rather than disproved. The fatigue result has not been repeated outside its one 132-patient trial.³ No trial has compared fruiting body, spore and mycelium preparations, counted infections as an outcome, or lasted beyond 24 weeks.¹³

Frequently asked questions

What is the main benefit of reishi?

Measured in people, fatigue: 28% against 20% on placebo in one 132-person, eight-week trial at 5.4 g a day of extract.³

Is reishi mushroom good for anxiety?

Untested as a primary outcome: lower anxiety scores in a 48-patient placebo-controlled pilot, no change in a placebo-controlled fibromyalgia trial.^{4, 10}

What are reishi and cordyceps good for?

One trial, part-funded by its supplement's supplier, combined them: 3 g a day with cordyceps changed no glucose measure in 84 people; what cordyceps does for the body has its own trials.⁸

How much reishi did the trials use?

1.4 to 3 g a day for 12 to 16 weeks, 5.4 g of extract a day for eight weeks, 6 g a day for six weeks; weight did not change in any of them, and the 2025 pooled analysis found no change in waist circumference or body fat.^{3, 7, 9, 13}

Is reishi a psychedelic?

No. Nothing in it is psychoactive and no trial reported intoxication; does lion's mane get you high? covers both mushrooms.

Sources

1. Jin X, et al. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane review, 5 randomised trials; non-commercial funding. Cochrane Database of Systematic Reviews, 2016. PubMed 27045603.
2. Narayanan S, et al. Medicinal mushroom supplements in cancer. Systematic review, 39 clinical studies. Current Oncology Reports, 2023. PubMed 36995535.
3. Tang W, et al. A Ganoderma lucidum polysaccharide extract in neurasthenia. Randomised placebo-controlled trial, 132 patients, 8 weeks; non-commercial funding. Journal of Medicinal Food, 2005. PubMed 15857210.
4. Zhao H, et al. Spore powder of Ganoderma lucidum for cancer-related fatigue in breast cancer. Randomised placebo-controlled pilot, 48 women, 4 weeks; funded by a provincial cancer society. Evidence-Based Complementary and Alternative Medicine, 2012. PubMed 22203880.
5. Chen SN, et al. Immune modulation by a beta-glucan from Ganoderma lucidum in healthy adults. Randomised placebo-controlled trial, size not in the abstract, 84 days; funding not stated. Foods, 2023. PubMed 36766186.
6. Wachtel-Galor S, et al. Ganoderma lucidum ("Lingzhi"): biomarker responses in a controlled human supplementation study. Placebo-controlled crossover trial, 18 adults, 4 weeks; non-commercial funding. British Journal of Nutrition, 2004. PubMed 14756912.
7. Klupp NL, et al. Ganoderma lucidum mushroom for the treatment of cardiovascular risk factors. Cochrane review, 5 trials, 398 adults; non-commercial funding. Cochrane Database of Systematic Reviews, 2015. PubMed 25686270.
8. Klupp NL, et al. Ganoderma lucidum for cardiovascular risk factors of metabolic syndrome. Randomised placebo-controlled trial, 84 adults, 16 weeks; investigator-led, part-funded by the supplement's supplier. Scientific Reports, 2016. PubMed 27511742.
9. Collado Mateo D, et al. Ganoderma lucidum improves physical fitness in women with fibromyalgia. Randomised trial against carob, 64 women, 6 weeks; non-commercial funding. Nutrición Hospitalaria, 2015. PubMed 26545669.
10. Pazzi F, et al. Ganoderma lucidum effects on mood and health-related quality of life in women with fibromyalgia. Randomised placebo-controlled pilot, 6 weeks. Healthcare, 2020. PubMed 33265969.
11. Wu DT, et al. Quality consistency of Ganoderma lucidum dietary supplements collected in the United States. Laboratory survey, 19 products; non-commercial funding. Scientific Reports, 2017. PubMed 28798349.
12. Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. gov.uk.
13. Jafari A, et al. The nutritional significance of Ganoderma lucidum on human health. GRADE-assessed meta-analysis, 17 randomised trials, 971 participants. Food Science and Nutrition, 2025. PubMed 40510787.
14. Wang X, et al. Ganoderma lucidum spore oil for triglyceride reduction. Randomised placebo-controlled trial, 110 adults with dyslipidaemia, 12 weeks. Nutrients, 2025. PubMed 40077714.
15. Cui XY, et al. Extract of Ganoderma lucidum prolongs sleep time in rats. Animal study. Journal of Ethnopharmacology, 2012. PubMed 22207209.
16. Food Standards Agency. Outcomes on novel food consultations (GB), updated 26 June 2026. gov.uk; Retained Regulation (EU) 2015/2283 on novel foods. legislation.gov.uk.

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