Lion’s mane mushroom (Hericium erinaceus) contains two groups of compounds, hericenones and erinacines, that appear to stimulate nerve growth factor in laboratory and animal studies. A small number of human clinical trials have tested lion’s mane for cognitive function, with mixed but generally positive results in mild cognitive impairment, mild Alzheimer’s disease, and healthy adults. The human evidence is still limited to small, short trials, so it does not yet prove the mushroom prevents or treats any brain disease.
Safety First: Who Should Be Extra Careful
Anyone with a known mushroom allergy should avoid lion’s mane, since allergic reactions, including skin rash and breathing symptoms, have been reported with mushroom supplements in general.
In the largest human trial to test lion’s mane in people with mild Alzheimer’s disease, some participants who took the supplement reported nausea, abdominal discomfort, and skin rash, and a few left the study because of these side effects. A broader review of lion’s mane research also lists stomach discomfort and headache as occasionally reported effects.
People who are pregnant or breastfeeding, people managing diabetes or blood sugar levels, and anyone taking prescription medication should talk with a qualified clinician before adding lion’s mane to their routine. Animal research suggests lion’s mane may lower blood sugar, which means it could interact with diabetes medication, though this has not been confirmed in human trials.
Lion’s mane is not approved by the FDA to diagnose, treat, cure, or prevent any disease. This article does not recommend a product, dose, or brand. See our medical disclaimer for the full safety scope.
What Is Lion’s Mane and Why Researchers Study It
Lion’s mane is a large, white, shaggy mushroom that grows on hardwood trees across Asia, Europe, and North America. It has a long history as both a food and a traditional remedy in China, Japan, and Korea.
Researchers are interested in lion’s mane mostly because of two groups of bioactive compounds it contains: hericenones, found in the fruiting body, and erinacines, found in the mycelium (the root-like network the mushroom grows from). In laboratory and animal studies, these compounds appear able to cross the blood-brain barrier and stimulate the production of nerve growth factor, a protein involved in the growth, survival, and repair of nerve cells.
Human Clinical Evidence: What Trials in People Actually Found
Human evidence for lion’s mane is still small in scale. Here is what the published clinical trials found, listed by the population studied.
Mild cognitive impairment (older adults)
A 2009 double-blind, placebo-controlled trial gave 30 adults aged 50 to 80 with diagnosed mild cognitive impairment either lion’s mane powder or a placebo for 16 weeks. The lion’s mane group showed improved scores on a standard Japanese cognitive function scale compared with placebo.
Mild Alzheimer’s disease
A 2020 double-blind, placebo-controlled trial followed 49 adults aged 50 to 90 with mild Alzheimer’s disease for 52 weeks. Participants took a mycelium-based capsule standardized to erinacine A. The treatment group showed significant improvement on standard dementia rating scales, including the Mini-Mental State Examination, compared with placebo.
Healthy young adults
A 2023 double-blind, placebo-controlled pilot study gave 41 healthy adults aged 18 to 45 either 1.8 grams of lion’s mane or a placebo. A single dose was linked to faster performance on a task that measures attention and processing speed, and 28 days of daily use was linked to a trend toward lower self-reported stress. The study authors described the findings as promising but preliminary, given the small sample size.
Systematic review of the evidence base
A broader review of medicinal mushroom research for cognitive impairment screened nearly 200 studies and found only three randomized controlled trials on lion’s mane, reishi, and cordyceps combined that were rigorous enough to include. Animal studies produced positive results far more consistently than the human trials did, which is a key limitation researchers point to when interpreting lion’s mane’s cognitive claims.
Evidence Hierarchy: From Lab Dish to Human Trial
Not all lion’s mane research carries the same weight. Here is how the evidence builds, from weakest to strongest:
- In-vitro (lab dish/cell) studies: Hericenones and erinacines can stimulate nerve growth factor production in isolated cells. This is the earliest, weakest signal and does not confirm effects in a living body.
- Animal studies: Lion’s mane extract has improved memory tasks and reduced markers of nerve damage in mice. This is suggestive, but animal biology does not always translate to humans.
- Small human pilot trials: Improved cognitive test scores or processing speed have been seen in adults with mild cognitive impairment and in healthy adults. This is a preliminary human signal, and small sample sizes limit confidence.
- Larger randomized controlled trials: Improved dementia rating scores over 52 weeks have been seen in adults with mild Alzheimer’s disease. This is the strongest evidence type available so far, though only a handful of trials exist.
Preclinical Findings: What Animal and Lab Research Suggests
Outside of human trials, most lion’s mane research is preclinical. Animal studies suggest lion’s mane extract may support the growth of new brain cells in the hippocampus, an area tied to memory, and may help protect against damage linked to amyloid-beta buildup, a protein associated with Alzheimer’s disease. Other animal research has looked at gut health, inflammation, and blood sugar regulation. None of this preclinical work has been confirmed to work the same way in people, so it should be read as a reason for further human research rather than as evidence of a benefit you can expect from taking the mushroom.
Evidence Limits You Should Know
- Most published human trials involved fewer than 50 participants, which makes it hard to rule out chance findings.
- Trial lengths ranged from a single dose to 52 weeks; there is no long-term human safety or effectiveness data beyond about a year.
- Lion’s mane products vary widely: fruiting body versus mycelium, hot-water extract versus alcohol extract, and standardized versus non-standardized erinacine content. A result from one type of extract does not necessarily apply to another product.
- No lion’s mane product is approved by a drug regulator to treat, cure, or prevent cognitive decline, dementia, or any diagnosed condition.
Frequently Asked Questions
Does lion’s mane mushroom actually improve memory?
Small human trials in people with mild cognitive impairment and mild Alzheimer’s disease have found improved scores on standard cognitive tests after weeks of supplementation compared with placebo. These are promising early results, not proof the mushroom prevents or reverses memory loss, and the trials involved small groups of people.
What are hericenones and erinacines?
They are the two main groups of bioactive compounds researchers study in lion’s mane. Hericenones come mainly from the fruiting body, and erinacines come mainly from the mycelium. Both have been shown in lab and animal studies to stimulate nerve growth factor, a protein involved in nerve cell growth and repair.
Is lion’s mane safe to take with medication?
This has not been thoroughly studied in humans. Because animal research suggests lion’s mane may affect blood sugar, anyone taking diabetes medication, or any other prescription medication, should ask a qualified clinician before use. People who are pregnant, nursing, or managing a health condition should do the same.
How is lion’s mane different from other “brain” mushrooms like reishi or cordyceps?
Each species has a different, mostly separate evidence base. Lion’s mane is studied mainly for nerve growth factor stimulation and cognitive test performance. Reishi and cordyceps have their own distinct compounds and research focus, and findings from one species should not be assumed to apply to another. See our evidence grading and source policy for how we separate species-specific claims.
Educational Disclaimer
This article is for general educational purposes only and is not medical advice. It is not a diagnosis, a treatment recommendation, or a substitute for care from a qualified clinician. Evidence for lion’s mane mushroom differs by extract type, dose, population studied, and study design, and most findings so far come from small or preclinical studies. Talk with a doctor or pharmacist before starting, stopping, or changing any supplement or medication, especially if you are pregnant, nursing, managing a health condition, or taking prescription drugs. For more on how we evaluate research, see our editorial standards and review process.