Lion's Mane

What it is

Lion's mane (Hericium erinaceus) — also called Yamabushitake or monkey head mushroom — is an edible and medicinal fungus long used in traditional Chinese medicine [1]. Supplements come as capsules, powders and drinks made from either the dried fruiting body or from mycelium grown in liquid culture; the two contain different compounds, with hericenones mainly in the fruiting body and erinacines mainly in the mycelium [2].

How it might work

In lab studies, compounds from lion's mane stimulate nerve growth factor and brain-derived neurotrophic factor, which support the growth and survival of nerve cells [1]. Erinacine A from the mycelium has been shown to reach the brain in animal studies [2]. These mechanisms are proposed; they have not been confirmed to explain any effects in people [1].

What the research says

Memory and thinking. In a 16-week trial, 30 adults aged 50 to 80 with mild cognitive impairment took 3 g a day of dried fruiting-body powder; their scores on a dementia rating scale rose more than the placebo group's, and slipped back after the supplement was stopped [3]. A 12-week trial in 31 healthy adults over 50 found a small rise in one 30-point cognitive score (29.19 to 30.00, versus 28.73 to 29.53 on placebo), with no differences on two other memory tests [4]. In 41 people with mild Alzheimer's disease, a 49-week trial of an erinacine-A-enriched mycelium extract (about 5 mg erinacine A a day) improved one thinking score within the supplement group and kept daily-function scores higher than placebo, but between-group differences on the main cognitive tests were not statistically significant [2].

Healthy adults. Trials in healthy younger adults have been largely null: a 28-day trial of 1.8 g a day in 41 adults found faster performance on one reaction-time task after a single dose but no improvement across other tests [5]; a single 3 g dose in 18 adults produced no overall cognitive or mood change [6]; a single 1 g dose in a 40-person crossover trial improved a few attention measures [7]; and 10 g a day for 4 weeks in 24 college-age adults had no effect on cognition [8].

Mood and sleep. A 4-week placebo-controlled trial in 30 menopausal women found lower depression scores and fewer complaints with lion's mane [9]. An 8-week study of 77 adults with overweight or obesity reported better depression, anxiety and sleep scores, but it was not blinded and showed no significant between-group difference on its depression scale [10]. The same review notes no difference in sleep-quality scores in the menopausal-women trial [1].

Overall, reviews describe the human evidence as promising but limited, with small, short trials and inconsistent results across tests [1].

Doses used in studies

Doses tested in trials, not recommendations: 3 g a day of dried fruiting-body powder for 16 weeks in mild cognitive impairment [3]; 3.2 g a day of fruiting-body powder for 12 weeks in healthy older adults [4]; about 1.05 g a day of erinacine-A-enriched mycelium (5 mg/g erinacine A) for 49 weeks in mild Alzheimer's disease [2]; 1.8 g a day for 28 days in healthy young adults [5]; 10 g a day baked into muffins for 4 weeks in college-age adults [8]; cookies for 4 weeks in menopausal women [9]; and 8 weeks of a mycelium-plus-fruiting-body supplement in adults with overweight or obesity [10].

Safety and interactions

Reported side effects are mostly mild: stomach discomfort, nausea, diarrhea and headache [1]. In a 49-week trial, 4 of 49 participants stopped the supplement because of abdominal discomfort, nausea or a skin rash [2]. More frequent periods were reported in one trial in menopausal women [1]. Rare allergic reactions have been reported, including one serious case of lung inflammation in a man taking a lion's mane supplement, so people with a mushroom allergy should avoid it [1]. No upper safe limit or toxic dose has been established in people; the largest dose tested in a published trial was 10 g a day for 4 weeks [8]. No human studies have looked at interactions with medicines. There are no safety data for pregnancy or breastfeeding; trials excluded pregnant and breastfeeding women [4].

Caveats and open questions

The trials are small — most included under 50 people — and they tested different products, doses and cognitive tests, which makes results hard to compare [1]. One study tracked mood only within the supplement group and was not blinded [10], and two trials disclosed industry involvement (a supplement company provided the product in one, and two authors were employed by a company whose drinks contain lion's mane in the other) [5][6]. A larger, 150-person trial of a commercial lion's mane product for cognitive health is recruiting (NCT06870136).