Reishi Mushroom: Traditions, Research, and Realistic Expectations
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What does the research say about reishi mushroom benefits for older adults?
Reishi has centuries of traditional use behind it and a small but growing body of modern research, most of it focused on how the mushroom interacts with the immune system. Direct evidence in older adults is limited to a handful of small trials, and most of what's published uses concentrated extracts at doses far higher than a typical supplement blend. This guide explains what the research actually shows, what it can't tell you, and how it relates — and doesn't — to RENEW.
What reishi is
Reishi (Ganoderma lucidum) is also known as lingzhi. It has a long history in East Asian traditional practice, where it was regarded as a valued natural material for more than two thousand years. Unlike tender food mushrooms such as shiitake, reishi has a hard, woody texture and is rarely eaten as food. It's typically prepared as a tea, extract, or powder instead.
Most reishi used in supplements today, including RENEW's, comes from mycelium — the fungus's underground, root-like network — grown and processed rather than the wild woody fruiting body harvested whole. RENEW's label names Reishi (Ganoderma lucidum) powder (mycelial biomass) as one part of its mushroom blend.
What the research in older adults actually shows
The most directly relevant human study is a double-blind, placebo-controlled trial published in the British Journal of Nutrition in 2024. Researchers enrolled 60 older women, of whom 39 completed the study — 23 taking 2,000 milligrams per day of a Ganoderma lucidum dry extract and 16 taking a placebo, for eight weeks — with the results read from laboratory measurements on blood samples. The authors' own conclusion is that the extract regulated normal immune-system function toward a predominantly anti-inflammatory pattern. That is a laboratory signalling measurement. The trial was not designed to measure, and did not measure, how any participant actually felt or fared.
Three details matter when weighing this result. First, the dose studied — 2,000 mg per day of a standardized dry extract taken on its own — is a specific, concentrated product, not a blend. Second, thirty-nine completers split across two groups is a small sample for drawing broad conclusions about "older adults" as a group, and this is one trial, not a replicated body of evidence. Third, every participant was an older woman, so the trial says nothing about men.
The broader immune research — and its limits
Reishi's best-studied research area is the everyday working of the immune system: several small randomized trials have looked at normal immune signalling in healthy adults, generally using extracts or purified beta-glucan fractions rather than whole mushroom powder. A 2025 peer-reviewed review covering reishi's chemistry, traditional use, and modern research describes this history in detail, but is candid about the state of the human evidence: many of the studies behind reishi's reputation are laboratory or animal research rather than large human trials, and the review calls for further research to confirm reishi's effects and establish appropriate use in specific populations. That gap between traditional use and confirmed human evidence is worth taking seriously rather than skipping past.
How this relates to RENEW — and how it doesn't
RENEW's label lists Reishi (Ganoderma lucidum) powder (mycelial biomass) as one of four mushrooms — alongside cordyceps, maitake, and shiitake — inside a combined 1,020 mg proprietary blend, included to support normal immune function. That is a different product, in a different form, at a different amount, than the 2,000 mg standardized dry extract studied on its own in the older-women trial above. A proprietary blend lists its components and their combined weight without a separate weight for each one, so the label does not say how many of those 1,020 milligrams come from reishi specifically. That means neither the older-adult trial nor the broader immune research can be read as evidence about what RENEW's reishi content does, and RENEW does not claim that it does.
The traditional-use history and general immune research above are background for why reishi is included in an immune-support formula — not a promise about a particular outcome. You can see the full blend, including what is and isn't broken out by amount, on the RENEW ingredients page. For a closer look at all four mushrooms in the blend and how the label discloses them, see our guide to RENEW's mushroom blend.
Safety and what to watch for
The NIH's LiverTox resource reports that reishi is "well tolerated and has not been associated with serum aminotransferase elevations during therapy," and states that given how widely it's used worldwide, clinically apparent liver injury from reishi "must be extremely rare." The same resource notes rare published case reports of liver injury, mostly tied to poorly documented cases where other causes weren't fully ruled out, and rates reishi a "possible rare cause" — its lowest confidence category for a suspected link. Commonly reported mild side effects include stomach upset and insomnia.
Because reishi may affect the immune system and blood clotting, it is not necessarily neutral to combine with certain medicines. Memorial Sloan Kettering's herb-interaction database advises that reishi "can increase your risk of bleeding" for anyone taking a blood thinner such as warfarin, and notes that because reishi "can enhance immune response," it may not be appropriate for people taking immune-suppressing medication.
Questions to ask your doctor
Bring your full supplement label to your next appointment and ask:
- I take a blood thinner. Could a reishi-containing supplement affect my bleeding risk?
- I take medication that suppresses my immune system. Is an immune-supporting supplement like this appropriate for me?
- I have a mushroom allergy or sensitivity. Does this product fit my situation?
- Does the lack of a separate reishi amount on the label change your advice for me?
These questions are meant to support a conversation with your doctor. They are not instructions to start, stop, or change any medicine or supplement on your own.
Written by The Novera Team. Last reviewed: 2026-08-11.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.