Medicinal Fungi · Clinical Nutrition · Immune Health · Cognitive Function
Medicinal Mushrooms —
What the Evidence Shows
Five species, graded. What each is used for, the trials behind it, the safety points, and how to read a label. The guide to the Fungi of the Month series, where each species gets its full evidence and a "How much" block.
Stephen Duncan
BSc (Hons) · PG Dip · MSc · FDN-P · Working With People Since 1988
June 2026 · updated October 2026
10 min read
Updated October 2026. This page used to give doses for five species, rate named brands, and make several unsourced claims. It is now the guide to the Fungi of the Month series. Each species gets a short, graded summary with its trials named, and the dose information lives only in each monthly edition, where it is shown with the trial it came from. Two claims were wrong: cordyceps did not improve VO₂ max in the trial usually cited, and the testosterone claim rests on mouse cell studies whose results point both ways. What changed and why →
Disclosure. Detective Health has commercial relationships with Amrita, Longevity Essentials and Synergistics, who sell medicinal mushroom products. Nothing below is a recommendation to buy any of them.
Years ago I attempted to grow shiitake mushrooms at home. Two growing "kits" — substrate blocks inoculated with spores — placed in a spare room and largely forgotten about. I came back to find that neither had produced anything resembling the tidy clusters the packaging had promised. What they had produced was a network of mycelium that had extended outward from the substrate, across the shelf, and begun growing into the carpet.
It's a useful picture of what fungi are: opportunists that spread into whatever darkness, moisture and food they're given. It's also a reminder that a mushroom supplement is a biologically active product, not a food flavouring. Which species, which part of the fungus, how it was extracted and how much of the active material is actually in the capsule all matter. The UK market has grown quickly over the last five years, and labels often don't answer those questions.
How to read this page
Each species below gets the same four things: what it's used for and how sure the evidence is, the trials worth knowing about, the safety points, and a link to its Fungi of the Month edition. The editions carry the full evidence and a "How much: what the trials used" block. This page carries no doses, because a dose without the trial, the population and the length of use behind it isn't information you can act on.
The grades are the same ones I use everywhere: strong (consistent randomised trials in people like you), mixed (some trials, small or inconsistent), mechanistic and untested (a plausible mechanism from cell or animal work, no human trial), and none.
The beta-glucan question
Beta-glucans are polysaccharides, long chains of glucose. They are the compounds most often credited with mushrooms' effects on the immune system. But "beta-glucan" on a label doesn't tell you which kind.
Two kinds of beta-glucan
1,3-1,4 Beta-Glucan · Grain-derived
Oat and barley beta-glucan
A linear soluble fibre that forms a gel in the gut. Its best-tested effect is lowering LDL cholesterol. It is a different molecule from the fungal kind, so immune claims made for mushrooms don't transfer to oat or barley products.
1,3-1,6 Beta-Glucan · Fungi and yeast
Mushroom and yeast beta-glucan
A branched structure that binds the Dectin-1 receptor on immune cells in laboratory studies. Grade: mechanistic. Whether a given supplement changes immune function in a healthy person hasn't been shown; the human trials that exist are of specific extracts in specific diseases (turkey tail below).
If a product's beta-glucan comes from oat or barley, it is a fibre supplement, not a mushroom one. If it comes from a mushroom, the label should say which species, which part, and how much beta-glucan per serving.
Fruiting body versus mycelium on grain
The fruiting body is the visible mushroom: cap, stem and gills. The mycelium is the network of threads the fungus grows through. Both contain active compounds, in different proportions depending on the species.
The quality problem is the substrate. Mycelium is quick and cheap to grow on grain such as brown rice or oats. Some products then mill the whole block, grain included, so a share of the powder you pay for is starch. How much varies by product and is rarely stated. That's why the checklist below asks for a stated beta-glucan content rather than a total "mushroom" weight.
Mycelium isn't always worse. The best-tested turkey tail extract, PSK, is made from mycelium, but it's grown in liquid culture and purified, which is a third thing again (see turkey tail below).
Five species: what the evidence shows
These are the five species the Fungi of the Month series covers. Maitake, shiitake and others have their own literature and are not covered here.
Used for, and how sure
Memory and thinking. In the lab, hericenones and erinacines stimulate nerve growth factor (mechanistic). In people, the trials are few, small and short. Grade: mixed. Claims for brain fog, ADHD, OCD, long COVID or gut motility have no human trials behind them (none).
The trial worth knowing
Mori 2009: 30 Japanese adults aged 50 to 80 with mild cognitive impairment, randomised to dried fruiting-body tablets (about 3 g a day) or placebo for 16 weeks. Scores were better than placebo at weeks 8, 12 and 16, then fell significantly within four weeks of stopping. The lead author worked for a mushroom producer (Hokuto Corporation).
Safety
No adverse effects on blood tests in the Mori trial. Trials have been too small and short to rule out uncommon harms. Avoid if you are allergic to mushrooms.
What the edition covers
The corrected trial details, what the trials used and for how long, and what to look for on a label.
Grade
Mixed: one small trial in mild cognitive impairment
Used for, and how sure
Immune support, sleep, stress and the liver. The human trials are in people with cancer, alongside chemotherapy or radiotherapy. Grade: mixed, from poor-quality trials. Its effects on cortisol, sleep and stress haven't been tested in randomised trials (mechanistic and untested).
The trials worth knowing
Jin 2016, a Cochrane review: five randomised trials in people with cancer. People given reishi alongside chemotherapy or radiotherapy were more likely to respond to treatment, and four trials reported better quality of life. The reviewers judged the trials' quality "generally unsatisfying", no trial measured survival, and they found no case for reishi as a first-line treatment.
Safety
Case reports of liver injury with reishi powder, including one death: Yuen 2004 (Hong Kong), Wanmuang 2007 (Thailand, fatal fulminant hepatitis), and Guedikian 2023 (taken with alcohol; recovered). Case reports can't say how common this is. Stop it and see your GP if you get yellowing skin or eyes, dark urine or pain under the right ribs. Check with your doctor first if you have cancer, or take blood-thinning or immune-suppressing medicines.
Removed from this page
"A bitter taste shows enough ganoderic acid" and "blood thinning at high doses". I couldn't find a source for either.
Grade
Mixed: poor-quality trials, in cancer only
Used for, and how sure
Energy and exercise capacity. Grade: mixed, from one small pilot trial. Claims about mitochondria, the OAT, the lungs and adrenal support haven't been tested in people (mechanistic and untested).
The trial worth knowing
Chen 2010: 20 healthy adults aged 50 to 75, a Cs-4 extract or placebo for 12 weeks. Two thresholds measured on an exercise bike rose (by about 9 to 11%) in the cordyceps group. VO₂ max did not change in either group. This page previously said the opposite.
Testosterone
The evidence is in mouse cells and mice, and it points both ways: cordyceps raised testosterone production in some experiments and suppressed hormone-stimulated production in others (Huang 2001; Hsu 2003; Huang 2004). Grade: mechanistic, animal; untested in people. It isn't a treatment for low testosterone.
Safety
The trial reported no safety problems, but 20 people for 12 weeks can't detect uncommon harms. There is no Fungi of the Month edition for cordyceps yet, so no dose is given anywhere on the site.
Grade
Mixed: one pilot trial; testosterone mechanistic, animal
Full edition
Not yet written
Used for, and how sure
The trial evidence is for PSK, a purified prescription extract made in Japan, given alongside chemotherapy after surgery for gastric cancer. Grade: strong for that use. It is not evidence for a turkey tail capsule taken for winter immunity, and it isn't a self-care dose. For the gut microbiome: one small trial in healthy people, no clinical outcome (mechanistic).
The trials worth knowing
Oba 2007: a meta-analysis of eight randomised trials, 8,009 patients after gastric cancer surgery. PSK plus chemotherapy improved survival compared with chemotherapy alone (hazard ratio 0.88, 95% CI 0.79–0.98). The two largest trials on their own found no difference. Pallav 2014: 24 healthy volunteers. The extract PSP changed the gut microbiome, with no health outcome measured.
Safety
Anyone having cancer treatment should only use it with their oncology team's agreement. That is where the evidence is, and also where interactions matter.
Removed from this page
"Directly addresses the estrobolome" and "beta-glucuronidase on GI-MAP → turkey tail". Neither has been tested in people.
Grade
Strong: PSK alongside gastric cancer chemotherapy. Mechanistic: microbiome
Used for, and how sure
Antioxidant, anti-inflammatory, blood sugar and anti-cancer claims. There are no published human trials. Grade: mechanistic and untested in people.
Safety: oxalate
Chaga is very high in oxalate. Case reports describe oxalate damage to the kidneys after long-term use of chaga powder, including kidney failure needing dialysis (Kikuchi 2014; Lee 2020). Case reports can't tell you how common it is. Avoid it if you have kidney disease or a history of kidney stones.
Also take care
If you take diabetes medicines, a blood-sugar-lowering effect has been reported in animal work but not measured in people. Ask your GP first. Don't use it instead of cancer treatment.
Removed from this page
"Blood thinning potential" and "highest antioxidant (ORAC) value of any food". I couldn't find a source for either.
Grade
None in people. Harm: case reports
How to read a mushroom supplement label: the quality checklist
This checklist is about whether a product contains what it says. It doesn't make a product effective; that depends on the evidence for the species and the use, above.
Before you buy — what to look for and what to avoid
✓ LOOK
The part of the fungus named: "fruiting body extract", or, for mycelium, how it was grown. If it says "full spectrum" or doesn't say, the product may be mycelium milled with its grain.
✓ LOOK
Extraction ratio listed (e.g., 10:1) — tells you the concentration relative to raw mushroom. A 10:1 extract from fruiting body contains ten times the concentration of raw dried mushroom. It also lets you compare a product with what a trial used.
✓ LOOK
Beta-glucan content stated per serving, ideally measured by a method that separates beta-glucan from starch. "Polysaccharides" alone can include starch from the grain.
✓ LOOK
Dual extraction noted (water + alcohol) — water extraction captures water-soluble polysaccharides and beta-glucans. Alcohol extraction captures fat-soluble triterpenoids (particularly important for Reishi and Chaga). Which fraction matters depends on the species and on what the trial used.
✗ AVOID
"Brown rice powder," "oat substrate," or "myceliated grain" in the ingredients list — these indicate the mushroom was grown on grain and the product includes the diluting starch substrate. Part of what you are paying for is grain starch, and the label won't usually say how much.
✗ AVOID
No dose or extraction information on the label — "proprietary blend" or a total "mushroom complex" weight without species-specific amounts. You can't compare it with any trial without knowing the amount of each species.
? ASK
Third-party testing certificate — for heavy metals (mushrooms bioaccumulate), pesticides (particularly relevant for wild-harvested Chaga), and mycotoxin contamination. If a company won't provide one, that tells you something.
Brands
This page used to rate named UK brands as "clinical" or "wellness". I've removed that table. The ratings weren't backed by product testing I could cite, and some of the brands are sold by companies Detective Health works with (see the disclosure at the top). Use the checklist above on any product, including ones I might suggest.
Testing and mushrooms: how sure is the link?
I sometimes use test results to decide whether a mushroom is worth a trial. A raised beta-glucuronidase on a GI-MAP might suggest turkey tail; a raised oxalate marker on an OAT means avoiding chaga. That's my practice, not something trials have tested. No trial has shown that choosing a mushroom from a stool, urine or hormone test improves outcomes. The oxalate caution rests on the chaga case reports, not on a test-guided trial.
Fungi of the Month
One species each month, with the trials and a "How much" block.
Each edition gives the full evidence for one species, a grade for each claim, what the trials actually used, and when to stop.
Edition 03 · September 2026
Edition 04 · October 2026
Sources
- Mori K et al. Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. Phytother Res 2009;23:367–72. PMID 18844328, doi:10.1002/ptr.2634
- Jin X et al. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database Syst Rev 2016;4:CD007731. PMID 27045603, doi:10.1002/14651858.CD007731.pub3
- Yuen MF et al. Hepatotoxicity due to a formulation of Ganoderma lucidum (lingzhi). J Hepatol 2004;41:686–7. PMID 15464254, doi:10.1016/j.jhep.2004.06.016
- Wanmuang H et al. Fatal fulminant hepatitis associated with Ganoderma lucidum (Lingzhi) mushroom powder. J Med Assoc Thai 2007;90:179–81. PMID 17621752
- Guedikian R et al. Ganoderma lingzhi (Reishi mushroom)-induced acute liver injury in the setting of alcohol use: a case report and review of the literature. Cureus 2023;15:e45953. PMID 37885515, doi:10.7759/cureus.45953
- Chen S et al. Effect of Cs-4 (Cordyceps sinensis) on exercise performance in healthy older subjects: a double-blind, placebo-controlled trial. J Altern Complement Med 2010;16:585–90. PMID 20804368, doi:10.1089/acm.2009.0226
- Huang BM et al. Effects of Cordyceps sinensis on testosterone production in normal mouse Leydig cells. Life Sci 2001;69:2593–602. PMID 11712663, doi:10.1016/s0024-3205(01)01339-x
- Hsu CC et al. Regulatory mechanism of Cordyceps sinensis mycelium on mouse Leydig cell steroidogenesis. FEBS Lett 2003;543:140–3. PMID 12753921, doi:10.1016/s0014-5793(03)00427-7
- Huang YL et al. In vivo stimulatory effect of Cordyceps sinensis mycelium and its fractions on reproductive functions in male mouse. Life Sci 2004;75:1051–62. PMID 15207653, doi:10.1016/j.lfs.2004.01.029
- Oba K et al. Efficacy of adjuvant immunochemotherapy with polysaccharide K for patients with curative resections of gastric cancer. Cancer Immunol Immunother 2007;56:905–11. PMID 17106715, doi:10.1007/s00262-006-0248-1
- Pallav K et al. Effects of polysaccharopeptide from Trametes versicolor and amoxicillin on the gut microbiome of healthy volunteers: a randomized clinical trial. Gut Microbes 2014;5:458–67. PMID 25006989, doi:10.4161/gmic.29558
- Kikuchi Y et al. Chaga mushroom-induced oxalate nephropathy. Clin Nephrol 2014;81:440–4. PMID 23149251, doi:10.5414/CN107655
- Lee S et al. Development of end stage renal disease after long-term ingestion of chaga mushroom: case report and review of literature. J Korean Med Sci 2020;35:e122. PMID 32419395, doi:10.3346/jkms.2020.35.e122
Before you buy a mushroom supplement
Check the species and the use against the grades above, read the label against the checklist, and if you have cancer, kidney disease or liver disease, or take blood thinners, diabetes or immune-suppressing medicines, talk to your doctor first. If you want help working out whether a supplement is worth a trial for you, start with an Initial Consultation.
Book an Initial Consultation (£145) →