The whole human evidence base is five trials, the largest of 41 people
A review of everything published between 2000 and June 2024 found 26 studies on lion's mane. Five were randomised trials in people; more than half was cell or animal work.
What the study found
Five trials, and the biggest analysed 41 people
A registered review of everything published on lion's mane between 2000 and June 2024 found 26 studies, more than half of them cell or animal work. Five were randomised trials in people. The largest of those analysed 41 participants, which is the ceiling of the entire human literature.
The caveat · Searched PubMed and nothing else
The search covered PubMed alone, so anything indexed only elsewhere or published in another language is missing, and nothing after June 2024 is included. The review's own design labels are wrong in places: it files one placebo-controlled trial as a cohort study.
What we don't know
Lion's mane's cognitive benefits come from small, short, often maker-funded trials, while independent trials in healthy adults found nothing against placebo. It is less a dispute than too little evidence to have one.