Lion's mane
Best evidence: Human trials, promising
Hericium erinaceus
Nothing here is medical advice and nothing here treats or prevents any disease. The grade on each claim describes the strength of the published evidence, not how well the mushroom works. The strongest grade on this page means: randomised controlled trials in people exist and point somewhere, but they are typically small, short and often industry-funded. promising is not proven.
What is actually being talked about
Hericenones in the fruiting body and erinacines in the mycelium, both of which stimulate nerve growth factor in laboratory work.
Claim by claim
Cognition and memory in older adults
Human trials, promising
A Japanese randomised trial in adults with mild cognitive impairment found improvement on a cognitive scale during supplementation, which faded after it stopped. It involved 30 people. Later trials have been similarly small, and it has not been replicated at a scale that would settle anything.
Mood and anxiety
Human trials, weak or mixed
A handful of very small studies, mostly in specific populations, with inconsistent results.
Nerve regeneration
Animal and cell studies only
The nerve growth factor effect is real in a dish and in rodents. Whether the relevant compounds cross the human blood-brain barrier in a capsule is not established.
The honest summary
The best case among the popular functional mushrooms and still a long way from proven. The honest position is that a small, unreplicated trial in 30 people is a reason to keep studying it, not a reason for the claims printed on the packaging.
Who should be careful
Generally well tolerated. Rare allergic and respiratory reactions have been reported.
What is actually in the jar
Insist on fruiting body. Lion's mane is one of the species most commonly sold as mycelium-on-grain, where the erinacines are in the mycelium but so is a great deal of grain starch. A supplement listing beta-glucan content, rather than vague polysaccharides, is telling you something real.
You can also just eat it. Which is a better argument than any capsule on this page. The lion's mane sheet
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The others, graded the same way
Turkey tail
Trametes versicolor
Approved as a drug
Reishi
Ganoderma lucidum
Human trials, weak or mixed
Chaga
Inonotus obliquus
Animal and cell studies only
Cordyceps
Cordyceps militaris, Ophiocordyceps sinensis
Human trials, weak or mixed
Shiitake
Lentinula edodes
Approved as a drug
Maitake
Grifola frondosa
Human trials, weak or mixed
Several of these interact with real medication. Reishi and cordyceps affect bleeding and blood sugar, chaga is high enough in oxalates to have caused kidney damage in heavy users, and anyone in cancer treatment should raise turkey tail with their oncology team rather than adding it independently. Tell your doctor what you are taking.