Health Benefits of the Reishi Mushroom
Health benefits of the Reishi mushroom (Ganoderma lucidum) what it may help with, what the human data actually show.
Reishi Mushroom health benefits
Reishi contains polysaccharides (notably β-glucans) and triterpenes thought to drive most biological activity, including immune modulation and antioxidant effects. A National Academies chapter summarizes these constituents and their lab/animal effects, plus early human trials that primarily measured immune markers.
What the human studies say
1) As an adjunct in cancer care (immune markers & quality of life)
A 2016 systematic review/meta-analysis of randomized and quasi-randomized trials (n≈373) found Reishi, used alongside standard therapy, improved some immune parameters (e.g., NK-cell activity) and quality-of-life scores versus controls. Survival benefits were not demonstrated; authors called for larger, better trials.
Earlier RCTs using a polysaccharide-rich extract (“Ganopoly”) likewise reported increased cytokines/NK activity and improved Karnofsky performance in advanced cancers, but these were from the same research group and primarily biomarker-focused.
In breast cancer survivors on endocrine therapy, a small 4-week randomized pilot (n=48) of spore powder 1000 mg three times daily reported improvements in fatigue, anxiety/depression scores, and inflammatory markers; this was exploratory and short-term.
Bottom line: There’s suggestive evidence for immune modulation and symptom relief as an adjunct, but no proven anticancer efficacy on its own.
2) Metabolic health (glucose, lipids, blood pressure)
A rigorous double-blind RCT in type 2 diabetes with metabolic syndrome (n=84) tested G. lucidum alone or with Cordyceps for 16 weeks and found no significant improvement in HbA1c, fasting glucose, lipids, or blood pressure versus placebo.
Bottom line: Current best trial evidence does not support Reishi for glycemic or cardiometabolic control.
3) Fatigue, mood, and “neurasthenia”
A double-blind RCT in patients diagnosed with neurasthenia reported global symptom improvements with a Reishi polysaccharide extract versus placebo; diagnosis criteria and generalizability are dated, but the findings align with the fatigue study above.
4) Other early signals
Small, modern trials continue to explore neurological and quality-of-life outcomes (e.g., add-on therapy in early Parkinson’s disease), but these remain preliminary and hypothesis-generating.
Safety, side effects, and interactions
Bleeding/hemostasis: In healthy volunteers, 1.5 g/day for 4 weeks did not significantly impair hemostasis versus placebo. That said, because case reports and interaction reviews raise concerns with anticoagulants, most clinicians advise caution with warfarin/antiplatelet drugs.
Liver: While many lab/animal papers suggest hepatoprotective effects, there are human case reports of liver injury—including a 2004 report and more recent cases, sometimes involving powdered products or fortified beverages. A LiverTox monograph summarizes the mixed picture. If you have liver disease or use alcohol heavily, discuss Reishi with your clinician first.
General tolerability: Across RCTs, adverse events were usually mild (e.g., dizziness, GI upset), but high-quality long-term safety data are limited.
Practical notes (what was used in trials)
Cancer adjunct (immune/QoL): Polysaccharide-rich extracts around 1.8 g/day for ~12 weeks in older trials; spore powder 3 g/day (1 g TID) for 4 weeks in the breast-cancer fatigue pilot.
Metabolic RCT: Extracts up to 3 g/day for 16 weeks showed no benefit on glycemic control.
Take-home
The strongest human evidence for Reishi is as an adjunct that can modestly improve immune markers and patient-reported outcomes (e.g., fatigue/QoL) in some cancer settings—not as a stand-alone anticancer treatment.
For blood sugar, lipids, and blood pressure, high-quality trials to date are negative.
Safety is generally acceptable short-term in trials, but rare hepatotoxicity has been reported, and drug–herb interactions (especially with anticoagulants) are a consideration. If you take warfarin/antiplatelets or have liver conditions, consult your clinician before use.
