Reishi (Ganoderma lucidum, also called Lingzhi) has human research behind it, but the studies are small and mixed, so it does not yet prove it works for any one purpose. Most of the best human work is in people with cancer, given alongside chemotherapy or radiation. The strongest review found a possible boost in tumour response, but no clear proof that reishi helps people live longer.
Reishi at a glance
| Item | What the studies used |
|---|---|
| Names you will see | Reishi, Lingzhi, Ling Zhi, Mannentake; the species is Ganoderma lucidum |
| Forms studied | Dried fruiting body, cultured mycelium extract, spore powder, water-soluble polysaccharide extract in capsules, yogurt with reishi beta-glucans |
| Doses used | From 225 mg per dose in a six-month trial to 1,800 mg three times a day in 12-week trials |
| Typical study length | From about 4 weeks to 12 months, with several trials running 12 weeks |
| Main studied uses | Cancer care, quality of life during chemotherapy, immune markers, blood sugar in type 2 diabetes, heart risk factors, antioxidant markers, mood and fatigue in breast cancer, colorectal adenomas |
| Strength of human evidence | Mixed and mostly small; the best-designed work is in cancer care; radiation and COVID-19 work is lab, cell and animal based |
What the human evidence shows
Cancer treatment: tumour response and survival
The NCI medicinal mushrooms summary, which reports studies mostly in people with cancer, says clinical trials of reishi products have been generally well tolerated. The strongest review is the 2016 Cochrane review of reishi in cancer, which pooled five randomized controlled trials (RCTs). In an RCT, people are randomly assigned to reishi or a comparison group, which makes it a strong design for comparing treatments. For a plain guide to these designs, see ingredient evidence vs marketing claims.
Pooled across the trials, people given reishi with chemotherapy or radiation were more likely to respond than those given chemotherapy or radiation alone (relative risk 1.50, meaning about 50% higher chance of response). The 95% confidence interval, the range where the true figure most likely sits, ran from 0.90 to 2.51. That range includes 1, which means no difference, so the result is not firm. Reishi alone did not reach the same response rate as combined treatment, and no trial recorded long-term survival.
The review
s authors wrote that the evidence was not sufficient to justify reishi as a first-line treatment for cancer, and that it remains uncertain whether reishi helps prolong long-term cancer survival.
Other cancer studies point in different directions. A placebo-controlled trial in people with advanced lung cancer who were not getting other anticancer treatment found more people had stable disease on reishi polysaccharides than on placebo. It also reported fewer fever, cough, weakness, insomnia and sweating, according to the CancerChoices reishi evidence summary. The NCI summary describes a separate open-label trial of 36 people with advanced lung cancer, treated alongside chemotherapy or radiation, who took a reishi polysaccharide extract for 12 weeks; it did not significantly change immune measures overall. A non-randomized controlled trial in women with HPV-positive cervical cancer reported higher tumor control after chemotherapy in women given reishi capsules.
Quality of life during chemotherapy
CancerChoices rates the evidence for better quality of life during chemotherapy as modest. That rating rests on a meta-analysis of studies in people with breast, colorectal, gastrointestinal or lung cancer. Four studies in the Cochrane review also reported relatively improved quality of life in the reishi groups, measured on the Karnofsky scale.
Immune markers in people with cancer
CancerChoices rates the evidence for higher immune markers in people with cancer as good. It also notes that a 2019 meta-analysis of 23 randomized trials of Coriolus versicolor and Ganoderma lucidum products found some markers higher with no overall effect. The Cochrane review reported that reishi raised the percentages of CD3, CD4 and CD8 markers on immune cells by 3.91%, 3.05% and 2.02%, with confidence intervals (1.92% to 5.90%, 1.00% to 5.11%, and 0.21% to 3.84%) that stayed above zero. In a small non-randomized controlled trial in people with breast cancer, IFN-γ was higher and TNF-α and IL-8 were lower during four cycles of chemotherapy than with chemotherapy alone.
Blood sugar in type 2 diabetes
CancerChoices rates the blood sugar evidence as preliminary, based on two small studies in people with type 2 diabetes. In one small placebo-controlled trial, 1,800 mg of a reishi polysaccharide extract taken three times a day for 12 weeks lowered HbA1c (a measure of average blood sugar over the prior two to three months), fasting insulin, blood glucose and insulin after eating. A 2015 Cochrane review, as CancerChoices summarizes it, found no effect on HbA1c across three trials and none on fasting plasma glucose. A hospital health blog on reishi says that in some cases its effect on blood sugar was worse than placebo.
Colorectal adenomas
Adenomas are growths in the colon that the NCI summary calls premalignant, meaning before cancer. The NCI reports studies mostly in people with cancer, so note that this study was in people with adenomas. In a Japanese study, 123 people took a water-soluble extract from cultured reishi mycelium at 1.5 g a day for 12 months. They were compared with 102 no-treatment controls from the same department, not a placebo group. The change in adenoma count was +0.66 in controls and −0.42 in the treated group (P < .01). Total adenoma size rose 1.73 mm in controls and fell 1.40 mm in the treated group.
Heart and cholesterol risk factors
A small placebo-controlled trial, summarized by CancerChoices as Chu et al. (2012), gave people with borderline blood pressure or cholesterol 1.44 g of reishi for 12 weeks. Body mass index did not change, but plasma insulin and HOMA-IR, a measure of insulin resistance, were lower than with placebo. The hospital health blog says reishi may raise HDL (“good”) cholesterol and lower triglycerides, and adds that more research is needed to confirm heart benefit.
Antioxidant markers in healthy adults
Two small placebo-controlled trials in healthy adults measured antioxidant activity rather than illness. Chiu et al. (2017) gave 225 mg capsules after lunch or dinner for six months and found higher total antioxidant capacity and higher antioxidant enzyme activity than placebo. Wachtel-Galor et al. (2004) found greater antioxidant activity after four weeks of reishi supplements than with placebo. The 2017 trial’s title also mentions liver-protective effects, but the result the summary reports is the antioxidant measures. These are lab measures, so they show what changed in the blood, not whether a health problem improved.
Fatigue, mood and appetite during hormone therapy for breast cancer
A small randomized pilot trial in women with breast cancer on endocrine (hormone) therapy, summarized by CancerChoices as Zhao et al. (2012), tested reishi spore powder. The reported results were less fatigue, less anxiety, less depression, better appetite and better cognitive function than controls. A pilot trial is an early, small test, so its results are a starting point. For the question about benefits for women, the human results here come from breast cancer studies like this one and the immune trial above, as well as a controlled cervical cancer trial.
Radiation protection and COVID-19
A 2020 radioprotection systematic review searched 1,109 records and found 15 eligible articles, none of them clinical trials. Its in vivo results came from mice exposed to gamma rays, and its human work was ex vivo, using human blood cells. The authors say human use needs further clinical research. A 2023 review on reishi and COVID-19 says the available evidence suggests possible effects and recommends preclinical and clinical evaluation to establish dose, efficacy and potential toxicity.
Doses used in studies
These are the doses researchers used in the trials above. They are not recommendations, and a dose from one form does not carry over to another.
| Use and trial | Who was studied | Form | Dose used | Length |
|---|---|---|---|---|
| Lung cancer, open-label (NCI summary) | Advanced lung cancer, alongside chemotherapy or radiation | Reishi polysaccharide extract capsules | 1,800 mg three times a day before meals | 12 weeks |
| Type 2 diabetes, small RCT (Gao et al., 2004) | People with type 2 diabetes | Reishi polysaccharide extract | 1,800 mg three times a day | 12 weeks |
| Borderline blood pressure and cholesterol, small RCT (Chu et al., 2012) | Adults with borderline blood pressure or cholesterol | Reishi | 1.44 g | 12 weeks |
| Colorectal adenomas (Japanese study, via NCI) | People with premalignant colorectal adenomas | Cultured reishi mycelium extract (MAK) | 1.5 g a day | 12 months |
| Antioxidant markers, placebo-controlled crossover (Chiu et al., 2017) | Healthy volunteers | Capsules | 225 mg after lunch or dinner | 6 months |
| Immune markers during chemotherapy (via CancerChoices) | People with breast cancer | Capsules | 100 g twice a day, as the summary states | 4 cycles of chemotherapy |
| Immune stimulation in children (Henao et al., 2018) | Children aged 3 to 5 | Yogurt with reishi beta-glucans | Daily | 12 weeks |
The 100 g figure is written that way in the CancerChoices summary. It is far above every other dose here, so check the original paper before you treat it as a dose.
Safety, side effects and medicine interactions
| Source | What it reports |
|---|---|
| NCI medicinal mushrooms summary (mostly people with cancer) | Clinical trials of reishi products were generally well tolerated. The FDA has not approved medicinal mushrooms as a treatment for cancer or any other medical condition. |
| 2016 Cochrane review of reishi in cancer | Minor adverse events, with nausea and insomnia reported in one study. No significant blood or liver toxicity was reported. The authors say use of the extract should be judicious. |
| Hospital health blog on reishi | Digestive disorders and a slight increase in stomach aches, which it calls very small and mild. It lists pregnant or breastfeeding women, people with blood disorders, people about to have surgery, and people with low blood pressure as groups to avoid reishi. |
| 2021 review of reishi’s clinical data | Clinical studies of interactions with foods and drinks, chronic use, teratogenicity, mutagenicity and genotoxicity are missing. |
What are the downsides of reishi?
The most common reported effects are mild. The 2016 Cochrane review found minor adverse events, with nausea and insomnia in one study. Its authors wrote that the extract’s use should be judicious, especially after thorough consideration of cost-benefit and patient preference. The hospital blog says reishi raised side effects about twice as often as placebo, but calls them very small and mild.
Is reishi hard on the liver?
The Cochrane review reported no significant liver toxicity across its trials. The hospital blog says powdered reishi can cause some liver damage, but adds that studies on this risk are limited and not confirmed with certainty.
Is reishi a psychedelic mushroom, and does it make you feel high?
The studies cited here describe reishi as a medicinal mushroom and report mild effects, such as nausea and insomnia in one trial. None of them addresses whether it is psychedelic or causes a high, so that question is not answered here.
What not to mix reishi with
The 2021 review of reishi’s clinical data lists interactions with foods and drinks among the missing clinical data. Ask a pharmacist to check any medicine you take before you start. The groups in the next section need a clinician’s check first.
Who should talk to a clinician first
- Anyone who is pregnant or breastfeeding.
- People with blood disorders, or who are about to have surgery.
- People with low blood pressure.
- People with cancer, who should involve their oncology team. CancerChoices notes that increased immune activation is not always beneficial, so the oncology team needs to determine whether immune activation would be favorable.
- People with diabetes or on medicines for blood sugar, since the blood sugar trials above measured effects on glucose and insulin.
What is still unknown
- Whether reishi helps people with cancer live longer. No trial recorded long-term survival, and the 2016 Cochrane review calls it uncertain.
- Whether reishi changes estrogen levels. This is not established; if you have a hormone-sensitive condition, ask your clinician before you start.
- Long-term safety, use in pregnancy, and interactions with foods and drinks. The 2021 review says clinical data on these are missing.
- Which form works best. The trials used different forms, including mycelium extract, polysaccharide fractions and capsules, so results do not transfer neatly from one to another.
- Trial quality. The Cochrane authors describe the methodological quality of the primary trials as generally unsatisfying.
- Lion’s mane versus reishi. There is no head-to-head comparison on this page, so no winner can be named. To see how the same questions apply to another ingredient, read ashwagandha benefits evidence.
- Mood, sleep and anxiety claims. The 2021 review says the reported anxiety, sedation and depression effects come mostly from preclinical studies, and that quality clinical data are intensely needed.
How to read a label that lists reishi
| What to check | Why it matters |
|---|---|
| Amount per serving, in mg or g | The trials report exact doses. The NCI notes there is no guarantee that labeled ingredients are present in the specified amounts, and amounts may vary from lot to lot. |
| Form | Whole fruiting body, mycelium grown on grain, or extract. The NCI notes fruiting-body polysaccharides are entirely beta-glucan, while mycelium grown on grain can contain alpha-glucans from the grain. |
| Extract type and percentage | Reishi contains polysaccharides, triterpenoids, proteins and other compounds, and the research has not settled which part drives the effects. |
| Blends | When reishi is one of many herbs, CancerChoices notes it is unclear whether an effect comes from reishi or from the other ingredients. If a label gives only a total blend weight, you cannot see how much reishi you get. |
| Species name | Labels may use Ganoderma lucidum, Ganoderma sichuanense or Lingzhi. The NCI notes many Ganoderma species are difficult to tell apart. |
| Batch testing | The NCI notes FDA good manufacturing practices require every finished batch to meet product specifications. Ask the company which tests each batch gets before you order. |
By ClinicalStudyConnect.com Research Desk
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.