Study Review: 17 Reishi Trials, 971 People, and Very Low Certainty Across the Board
Most Reishi coverage, including some of ours, works one study at a time. That is useful for understanding a mechanism and nearly useless for answering the question buyers actually have, which is whether the accumulated human evidence adds up to anything.
A 2025 systematic review took a run at that question. It is the least exciting Reishi paper published in years, and probably the most useful one.
The study
Jafari A, Mardani H, Mirzaei Fashtali Z, Arghavan B. The Nutritional Significance of Ganoderma lucidum on Human Health: A GRADE-Assessed Systematic Review and Meta-Analysis of Clinical Trials. Food Science and Nutrition. 2025;13(6):e70423. doi:10.1002/fsn3.70423. PMID 40510787.
What they did
The authors searched EMBASE, PubMed, Web of Science, and Scopus through August 2024, and pooled 17 randomised controlled trials covering 971 participants in total. Risk of bias was assessed with the Cochrane Risk of Bias 2.0 tool, and each pooled outcome was graded using GRADE, a formal system for rating how much confidence an estimate deserves.
That last step is what makes this paper worth your time. Plenty of reviews report a pooled number. Fewer state plainly how much weight that number can bear.
What reached significance
Four outcomes showed a statistically significant pooled difference, reported as weighted mean differences.
- BMI: -0.43 (95% CI -0.77 to -0.10), p equals 0.011
- Creatinine: -0.14 (95% CI -0.27 to -0.02), p equals 0.028
- Glutathione peroxidase: +2.29 (95% CI 1.67 to 2.92), p less than 0.001
- Heart rate: -3.92 (95% CI -7.45 to -0.40), p equals 0.029
Every one of those four carried a GRADE certainty rating of very low.
What did not move
The null list is longer than the significant one, and it contains most of what Reishi is marketed around.
Body fat, waist circumference, body weight, and waist-to-hip ratio showed no significant pooled effect. Neither did systolic or diastolic blood pressure, fasting glucose, or any of the lipid measures: HDL cholesterol, LDL cholesterol, total cholesterol, and triglycerides. The inflammatory markers hs-CRP and TNF-alpha were null. So were the liver enzymes ALT and AST.
Worth noting for this site’s readers specifically: sleep was not among the pooled outcomes. The review’s scope was nutritional and metabolic indices, and the human trial base was not there to pool a sleep endpoint. Reishi’s sleep story currently rests on mechanistic and animal work, which we have covered separately, rather than on pooled human trials.
What “very low certainty” actually means
GRADE ratings run from high to moderate to low to very low, and they describe confidence in the estimate rather than the size of the effect. A very low rating is not a technicality. Its formal meaning is that the true effect is likely to be substantially different from the estimate, and that any real confidence in the number is unwarranted.
Ratings get downgraded for risk of bias in the underlying trials, inconsistency between them, imprecision from small samples, indirectness, and signs of publication bias. Reaching very low across every single outcome means multiple problems stacked on nearly every question, which is what you would expect from a literature of 17 trials averaging under 60 participants each.
Practically, it means the BMI result above should be read as “the pooled trials leaned this way” and not as “Reishi reduces BMI by 0.43.” The authors state the limitation in one sentence: the quality of evidence was very low across all outcomes. Their overall conclusion is that Ganoderma lucidum supplementation may have modest effects on certain health indices, with the evidence limited by very low quality.
The review reports receiving no specific funding, which removes one of the usual reasons a synthesis might read charitably.
Our read
Two things are true at once here, and marketing in this category tends to keep only the first.
Reishi has a large and genuinely interesting preclinical literature. It also has a thin human trial base, made up of small studies with methodological weaknesses, which does not currently support confident claims about metabolic, cardiovascular, inflammatory, or liver outcomes.
For a buyer, the practical consequence is that the evidence base is not where you should be trying to differentiate between brands, because it is not currently strong enough to differentiate Reishi from placebo on most endpoints. What you can differentiate on is product quality: what species and part you are actually getting, verified beta-glucan content, whether triterpenes were extracted at all, contaminant testing, and whether the lab doing the work is credible. Those are answerable questions with real documentation behind them.
We would rather point you at a certificate of analysis you can check than at a pooled estimate the authors themselves say deserves very little confidence.
Related reading
- Study Review: A Single Dose of Lion’s Mane Did Not Improve Overall Cognition
- Review: Reishi Mushroom and Blood Sugar Regulation Research
- Review: Reishi Mushroom and Cancer Immunotherapy Research