Lion's Mane and Memory: What the Human Trials Actually Found

A few small human trials suggest Lion's Mane (Hericium erinaceus) may modestly raise scores on cognitive screening tests in older adults with mild cognitive impairment. The trials are short, involve a few dozen people each, and use different products. None shows that Lion's Mane prevents or treats dementia.

Marketing often says Lion's Mane "improves memory and focus". This article looks only at the human studies behind that claim, trial by trial.

The Trial Everyone Cites: Mori et al. 2009

The best-known study comes from Japan (Mori et al., Phytotherapy Research, 2009). It was double-blind and placebo-controlled.

• Who: 30 Japanese men and women aged 50–80 with a diagnosis of mild cognitive impairment, split into two groups of 15.
• What: tablets of dried Lion's Mane fruiting body powder. The study dose was 3 g per day (four 250 mg tablets, three times daily).
• How long: 16 weeks, then 4 weeks of follow-up without tablets.
• Result: the Lion's Mane group scored higher than placebo on a Japanese dementia screening scale at weeks 8, 12 and 16. Four weeks after stopping, the scores fell significantly.

Two points matter. First, 15 people per group is very small. Second, the lead author worked at a mushroom company's laboratory, according to the paper's affiliations. That does not make the result wrong, but it is a reason to want independent replication.

What Did Later Trials Find?

Saitsu et al. 2019. A 12-week placebo-controlled trial of a fruiting body supplement used three cognitive tests. Only one, the Mini-Mental State Examination (MMSE), showed a benefit. The other two memory tests did not (Saitsu et al., Biomedical Research, 2019).

Li et al. 2020. This pilot trial in Taiwan enrolled people with mild Alzheimer's disease. It used a different product: mycelium enriched with erinacine A, three 350 mg capsules a day, for 49 weeks. The treated group improved on the MMSE, while the placebo group declined on another screening test. Four participants dropped out because of stomach discomfort, nausea or skin rash (Li et al., Frontiers in Aging Neuroscience, 2020). Several authors were employed by a Taiwanese biotech company, Grape King Bio.

Docherty et al. 2023. This UK pilot tested healthy adults, not older people. Forty-one participants aged 18–45 took 1.8 g a day or placebo for 28 days. After a single dose, the Lion's Mane group was faster on one attention task (the Stroop test). Over 28 days there was a trend toward lower self-reported stress that did not reach statistical significance. The authors also reported null and some negative findings and urged caution (Docherty et al., Nutrients, 2023).

A 2025 systematic review pooled MMSE results from one randomised and one pilot trial. The combined gain was about 1.2 points on the test's 30-point scale (Menon et al., Frontiers in Nutrition, 2025).

Why Should You Read These Results Cautiously?

• Small samples. Each trial had tens of participants, not hundreds. Small trials often overestimate effects.
• Different products. Fruiting body powder and erinacine-enriched mycelium are not the same material. Results from one do not transfer to the other. Our article on the wider cognitive claims for Lion's Mane discusses this further.
• Screening tools, not diagnoses. The MMSE and similar scales are quick screening tests. A one-point change is not the same as a noticeable difference in daily life.
• Effects may not last. In the Mori trial, scores dropped once people stopped.
• Industry involvement. Two of the four trials had authors employed by producers.
• Healthy people. For young healthy adults, the only trial found one faster reaction time and little else.

Put simply, the human evidence is promising enough to justify bigger trials. It is not strong enough to call Lion's Mane a proven memory enhancer.

Safety, Side Effects and When to See a Doctor

Lion's Mane is a widely eaten culinary mushroom, and the trials above reported few problems. Reported side effects include stomach discomfort, headache and allergic reactions (Menon et al., 2025), and the Li trial lost participants to nausea and rash.

• Mushroom allergies. Avoid it if you react to other mushrooms.
• Medication. Interaction data are very limited. If you take regular medication, especially for blood clotting, diabetes or dementia, ask your doctor or pharmacist first.
• Pregnancy and breastfeeding. No safety data exist for supplement amounts. Avoid it.
• Memory changes. New forgetfulness deserves a medical check. Causes such as vitamin B12 deficiency, thyroid problems, depression or medication side effects are treatable, and a supplement can delay that diagnosis.

If you want to try the mushroom itself, our dried Lion's Mane fruiting bodies are a whole-food form similar to the material in the fruiting body trials, but we make no claim that they improve memory. For a checklist on choosing any mushroom product, see our mushroom supplement checklist. For preclinical work on nerve insulation, see Lion's Mane and myelin.

Frequently Asked Questions

Does Lion's Mane improve memory?

A few small trials in older adults with mild cognitive impairment found modest gains on screening tests. The evidence is preliminary, and it does not show that Lion's Mane prevents or treats dementia.

What dose was used in the Mori 2009 trial?

Participants took four 250 mg tablets of dried Lion's Mane powder three times a day, about 3 g daily, for 16 weeks. This is a study fact, not a dosing recommendation.

Does Lion's Mane work for healthy young adults?

Only one small pilot trial has tested this. It found faster performance on one attention task after a single dose and a non-significant trend toward lower stress after 28 days.

Do the effects last after stopping?

In the Mori 2009 trial, cognitive scores fell significantly four weeks after participants stopped taking Lion's Mane.

Is Lion's Mane safe?

It is a common culinary mushroom and trials reported few problems, but side effects such as stomach discomfort, headache, nausea, rash and allergy are reported. Ask a doctor first if you take medication or are pregnant.

This article is for educational purposes only and is not medical advice. It does not replace a consultation with a doctor or pharmacist, especially if you take medication, have a health condition, or are pregnant or breastfeeding.