Hericium erinaceus, and Every Human Lion's Mane Trial

Lion’s mane is Hericium erinaceus, an edible mushroom, and it has been tested in people roughly eight times. Those trials measured a short and specific list: a dementia screening score in Japanese adults with mild cognitive impairment, questionnaire scores in thirty women, reaction time on one attention task in young adults, daily living scores in patients with mild Alzheimer’s disease, and hand dexterity ninety minutes after a single drink. Three trials in healthy adults measured cognitive performance and found no difference against placebo.

That is the whole human evidence base, and it is not what the first page of results says. This page lists every one of those trials with its size, population, dose, duration and result, including the ones that failed. It then explains the distinction that decides what is inside a capsule, fruiting body against mycelium, which in the European Union are not even the same regulatory category. What an adaptogen is at all is covered in our definition page.

What Hericium erinaceus is, and the five names it goes by

Hericium erinaceus is a wood-rotting fungus that fruits on dead or dying hardwood, mostly beech and oak, in temperate forests across Europe, North America and East Asia. It does not form a cap and a stem. It grows as a single cream-white mass hung with soft spines a few centimetres long, which is where every one of its common names comes from.

English calls it lion’s mane. German calls it Igelstachelbart, the hedgehog spine beard, and sells it under Lion’s Mane and Hericium alike. French calls it crinière de lion, Italian criniera di leone, Japanese yamabushitake after the spined robes of mountain ascetics. One organism, five marketing names, and that is why the same mushroom appears at very different prices.

Two things follow. Hericium erinaceus is food, not a herb: it is cooked and eaten in Japan and China and sold fresh in European markets. And Hericium coralloides and Hericium americanum are different species in the same genus, not what the trials used.

How to read a lion’s mane study before you read a lion’s mane claim

Almost every page quotes the same two Japanese trials without saying what would have to be true for them to mean anything. Six things decide that, and every trial below is described against all six.

Which part of the fungus. Fruiting body and mycelium contain different molecules and are regulated differently in the EU. A trial on one tells you very little about a product made from the other, and most articles do not say which was used.

Trial size. The largest human trial of lion’s mane published had 77 participants. Most had between 24 and 41, split across two arms. Groups of that size generate signals, not settled facts.

Population. The positive cognitive results come from people with a diagnosed impairment or from adults over 50. The null results come from healthy students. A result in one of those groups says nothing about the other.

Duration, and what happened after it ended. Trials run from a single dose to 49 weeks. In the trial everyone cites, scores fell back after participants stopped, which is a detail almost no summary carries.

How many outcomes were measured. Several trials ran three or more cognitive tests and reported one that moved. When you measure enough things, one of them moves. A single positive test out of three is a reason for a bigger trial, not a conclusion.

Who supplied the material. Two of the more recent studies were run with product supplied by, or with authors employed by, the company selling it. That is disclosed in the papers and it is not disqualifying, but the field is small enough that it is worth knowing.

Apply those six and the subject changes shape. There is a genuine, small, partly contradictory evidence base, and there is a much larger set of claims resting on cell culture work that never involved a person.

Fruiting body or mycelium, and why the label decides what is in the capsule

This is the distinction that separates an informed buyer from a hopeful one, and hardly any page in any language makes it.

Two families of compounds are named in almost every article about the Hericium erinaceus effect. Hericenones were isolated from the fruiting bodies. Erinacines were isolated from the cultured mycelium, the thread-like vegetative network the fungus grows before it fruits. A 2025 paper in the Journal of Natural Products from Kawagishi’s group, who found these molecules in the first place, describes hericenones C to H from the fruiting bodies and erinacines A to I from the mycelia. Both families stimulated nerve growth factor synthesis in cell culture and in animals. Neither has been shown to do that in a person, because nobody has measured it in one.

So a capsule of dried fruiting body powder and a capsule of erinacine-enriched mycelium are chemically different products sold under one name.

In Europe they are also legally different products. The European Commission runs a novel food status catalogue, a non-binding orientation tool built on whether a food was consumed to a significant degree in the Union before 15 May 1997. The Hericium erinaceus fruiting body, and aqueous extract powder made from it, clear that date and are not novel. Dehydrated mycelium powder does not, and is listed as an unauthorised novel food requiring authorisation under Regulation (EU) 2015/2283. The burden of proving pre-1997 consumption sits with the business selling the product, not with the regulator.

Read that against the trial list below and an awkward fact appears: the longest and most positive human trial used the mycelium form.

What to do with this. Look for the words fruiting body or Fruchtkörper on the pack. If it says mycelium, mycelial biomass, or nothing at all, you are buying something with a weaker European regulatory footing and, if it is grain-grown mycelium, a good deal of the grain.

Every human lion’s mane trial, and what each one measured

Trial	Population	Dose and duration	Measured	Result
Mori et al. 2009, Phytotherapy Research	30 Japanese adults aged 50 to 80 with mild cognitive impairment	about 3 g per day of dried fruiting body powder, 16 weeks	Revised Hasegawa Dementia Scale	higher scores than placebo at weeks 8, 12 and 16; scores fell after intake stopped
Nagano et al. 2010, Biomedical Research	30 women, cookies rather than capsules	4 weeks	CES-D depression scale, Kupperman index, Pittsburgh sleep index, indefinite complaints index	CES-D and complaints index lower than baseline; sleep and menopausal index not reported as separating
Saitsu et al. 2019, Biomedical Research	31 healthy Japanese adults aged over 50	fruiting body supplement, 12 weeks	MMSE, Benton visual retention, verbal paired associate learning	MMSE alone moved; the other two tests did not, and both groups improved over time
Li et al. 2020, Frontiers in Aging Neuroscience	41 patients with mild Alzheimer’s disease completed	three 350 mg erinacine-enriched mycelium capsules daily, 49 weeks	MMSE, cognitive screening, daily living, contrast sensitivity, blood markers	daily living score separated between groups; four participants withdrew with abdominal discomfort, nausea or rash
Grozier et al. 2022, International Journal of Exercise Science	24 college-age adults	10 g per day baked into muffins, 4 weeks	Stroop and mental arithmetic under exercise, metabolic flexibility	no significant effect on any measured variable
Docherty et al. 2023, Nutrients	41 healthy adults aged 18 to 45	1.8 g per day, single dose and 28 days	Stroop, word recall, working memory, stress and mood scales	faster Stroop 60 minutes after one dose; word recall accuracy worse after that dose; stress trend at 28 days did not reach significance
Surendran et al. 2025, Frontiers in Nutrition	18 healthy adults, mean age 23	3 g of a 10 to 1 fruiting body extract, single dose	global cognition, mood, executive function, pegboard	pegboard speed higher at 90 minutes; global cognition and mood unchanged; two executive function tests worse

The two trials everyone cites

Mori and colleagues (2009) ran a double-blind, placebo-controlled trial in 30 Japanese men and women aged 50 to 80 with diagnosed mild cognitive impairment, using roughly 3 g per day of dried fruiting body powder for 16 weeks. Scores on the Revised Hasegawa Dementia Scale were higher than placebo at weeks 8, 12 and 16. Then the trial kept watching for four more weeks after intake stopped, and the scores came back down. That last sentence is the most useful thing in the paper and it is missing from nearly every article that quotes it.

Nagano and colleagues (2010) gave 30 women biscuits containing Hericium erinaceus, or placebo biscuits, for four weeks and reported lower scores on a depression scale and on an index of unspecific complaints than before intake. Thirty women, four weeks, questionnaires, biscuits. It appears in every listicle because there is very little else.

The trials in healthy adults, including three that measured nothing

This is where the marketing and the literature part company. Saitsu and colleagues (2019) ran 31 healthy Japanese adults over 50 through three cognitive tests over 12 weeks and reported movement on one of the three. Grozier and colleagues (2022) fed 24 college-age adults 10 g per day in muffins for four weeks and found no effect on anything they measured. Docherty and colleagues (2023) gave 41 adults 1.8 g per day for 28 days: the group was faster on the Stroop task an hour after a single dose, and less accurate on immediate word recall after that same dose, and the reduction in subjective stress at 28 days did not reach statistical significance. Surendran and colleagues (2025) tested a single 3 g dose of fruiting body extract in 18 young adults and found faster pegboard performance at 90 minutes, no change in overall cognition or mood, and worse scores on two executive function tasks.

Three trials in healthy people, three sets of results that do not agree. If you are a healthy adult under 50, that is the evidence you are actually buying into.

The Alzheimer’s trial, and the form it used

Li and colleagues (2020) ran the longest study in the field: 49 weeks, patients with mild Alzheimer’s disease, three 350 mg capsules a day of a mycelium preparation standardised for erinacine A. Instrumental daily living scores separated between the groups and contrast sensitivity was better in the treated group. It is one pilot trial in a patient population, run in Taiwan with the manufacturer’s product, and it studied the mycelium form that the European catalogue lists as an unauthorised novel food. It cannot be used to describe what a fruiting body capsule does in a healthy person in Zurich or Manchester.

What no trial has measured, including the question most people are asking

ADHD. Search volume for lion’s mane and ADHD is large and growing, and there is no randomised trial of Hericium erinaceus in adults or children with an ADHD diagnosis. The published work in this direction is a rodent protocol. Anyone recommending lion’s mane for ADHD is extrapolating from attention tasks in people without the diagnosis, and in those tasks the results conflict.

Lion’s mane benefits for males specifically. No trial has recruited men only, and none has reported male-specific outcomes. The trials are mixed-sex or, in Nagano 2010, women only.

Long-term use in healthy people. The longest trial in a non-patient group ran 12 weeks. Nothing is published about taking it for years.

Anything about disease. Memorial Sloan Kettering’s herb monograph states plainly that there are no human studies showing anti-cancer effects, despite a large cell-culture literature. That pattern, strong laboratory findings and absent human confirmation, describes most of what is written about this mushroom.

Dose, timing, and how long before anything shows up

Published human doses run from about 0.5 g to 3.2 g of powder per day, with one acute study using a single 3 g dose of a concentrated extract and the Alzheimer’s trial using 1,050 mg per day of erinacine-standardised mycelium. There is no established serving for a healthy adult, and under Regulation (EC) 1924/2006 no health claim for Hericium erinaceus is authorised in the EU or the UK, so no amount can legally be tied to an outcome on a label.

Timing is the question asked most often, and the honest answer has two halves. The acute studies measured changes 60 to 90 minutes after a single dose on specific reaction-time tasks, and those changes did not extend to overall cognition. The trials that reported score changes on clinical scales ran 12 to 49 weeks. Nothing in the literature supports a meaningful judgement after a fortnight.

What to do with this. If you try it, give it a defined trial period of at least eight weeks at the serving on the pack, change nothing else at the same time, and decide at the end rather than in week two.

What to check before buying a lion’s mane supplement

There is no such thing as the best lion’s mane supplement in the UK, because no independent body ranks them. Four checks separate a serious product from a repackaged one.

Fruiting body or mycelium, stated on the pack. If it is not stated, assume mycelium on grain. This is the single most informative line on a label.

Extract ratio or plain powder, and the weight of each. A 10 to 1 extract at 500 mg and 500 mg of dried powder are ten-fold apart in starting material. A pack that gives a milligram figure with no indication of which is telling you almost nothing.

Where it was grown and tested. Mushrooms accumulate what their substrate contains. Ask the seller for heavy metal testing on the finished batch, and treat a refusal as an answer.

What else is in the capsule. A blend can be honest or a way to make 50 mg of the named ingredient look like a serving. Read the declared weight of each active.

Our own lion’s mane and shilajit capsules hold 250 mg of the named active plus 250 mg of shilajit extract per capsule, and that arithmetic is on the pack for this reason.

Taking lion’s mane with shilajit, or with ashwagandha

Shilajit is a mineral-rich resinous exudate collected from high-altitude rock, and its own human evidence is audited in our shilajit benefits article. The two are paired in a capsule because they are separately studied ingredients with non-overlapping trial literatures, not because a trial has tested them together. No study has. The same is true of the ashwagandha and lion’s mane combination people ask about: ashwagandha’s own trials are numerous and mostly about stress scales, and none of them included lion’s mane.

A stack is a convenience, not evidence. If you want the evening equivalent of this question, reishi is the mushroom asked about next.

What to do with this. Judge a combination product on the declared weight of each ingredient and the evidence for each one separately. That is all anyone has.

Side effects, and who should not take it

Lion’s mane is well tolerated in the published trials, and the reported complaints are mild and digestive. The 2025 systematic review in Frontiers in Nutrition, covering 26 studies including five randomised controlled trials, lists stomach discomfort and diarrhoea as the common ones, with single reports of headache and altered menstrual frequency. Four participants withdrew from the 49 week Alzheimer’s trial with abdominal discomfort, nausea or skin rash. The LiverTox database of the National Institute of Diabetes and Digestive and Kidney Diseases rates lion’s mane an unlikely cause of clinically apparent liver injury, with no cases in the major registries of herb-related liver injury.

The serious report is a single one. Nakatsugawa and colleagues (2003), in Internal Medicine, describe a 63 year old man who developed acute respiratory distress syndrome with diffuse infiltration in both lungs after taking a commercial Hericium erinaceum extract for about four months. A lymphocyte stimulation test reacted strongly to the extract, he required mechanical ventilation, and he recovered after steroid therapy. One case in more than twenty years is rare, and it is the reason the exclusions below are not decoration.

Mushroom allergy. If you react to mushrooms in food, do not take a concentrated mushroom supplement. This is the exclusion the case report speaks to most directly.

Asthma and respiratory conditions. Given that case report, anyone with asthma or another chronic lung condition should raise it with a doctor before starting, and stop at once if breathing changes.

Prescribed medication. No human interaction studies exist. That is not reassurance, it is an absence. If you take anticoagulants, antiplatelet drugs or diabetes medication, speak to a doctor or pharmacist first.

Pregnancy and breastfeeding. Not tested. Avoid.

Children. Not tested. Not for them.

Nothing here establishes that lion’s mane acts on any disease, and no European health claim for it is authorised. A page that tells you otherwise is making a claim it is not permitted to make, which is a useful filter for the rest of what it says.

So does lion’s mane do anything?

Three things decide it, and none of them is a benefits list. First, which group you are in: the trials that reported score changes recruited people with a diagnosed impairment or adults over 50, and the trials in healthy young adults mostly measured nothing. Second, whether you can accept an evidence base of eight small studies in which the most positive one used a form of the fungus that European regulators treat as unauthorised. Third, whether the pack in front of you states fruiting body or mycelium, an extract ratio, and a weight per capsule, because without those three lines you cannot tell what you bought.

If that honest version is enough for you, the useful next step is the arithmetic on the label rather than the promise on the front of it. If you want the wider map before you decide anything, what an adaptogen actually is is the page that puts this mushroom next to the seven others people are choosing between.