Lion’s Mane Mushroom Is Sold for Brain Health Based on Slim Evidence

Studies of the supplement are small and inconclusive

Beth Howard

Updated September 03, 2025

A lion's mane mushroom growing on a tree

PlazacCameraman/Getty Images

It’s easy to understand why lion’s mane is touted as a brain-boosting supplement. This edible mushroom, which is named for its shaggy, hair-like appearance, contains two chemicals that, in lab studies, promote the production of a protein called nerve growth factor that’s important for the health of neurons.

Nerve growth factor helps to support nerve cells, including those that decline with age and when Alzheimer’s disease occurs.

The two chemicals — hericenones and erinacines — are the reason the mushrooms, in supplement form, are marketed for improving mood and cognitive health. In mouse studies, extracts of lion’s mane reduced the number of amyloid plaques in the brains of mice engineered to have Alzheimer’s disease. The extract also increased production of new nerve cells in other studies in mice.

But the evidence for using the supplement in humans to enhance brain function, much less to stave off dementia, is slim at best, says neuroscientist Yuko Hara, director of Aging and Alzheimer’s Prevention at the Alzheimer’s Drug Discovery Foundation and an adjunct faculty member in neuroscience at the Icahn School of Medicine at Mount Sinai in New York City.

“There have been several clinical trials in healthy populations, as well as in Alzheimer's patients,” but there is a need for much larger studies, Hara says. “Further evidence is needed to determine whether lion's mane is, in fact, beneficial for cognitive function or improving the symptoms of dementia.”

What did the small studies find?

In a study reported in 2008 in Phytotherapy Research, 30 people ages 50 to 80 with mild cognitive impairment took lion’s mane or a placebo (dummy) pill every day for 16 weeks. Afterwards, those on the supplement had higher scores on a cognitive function scale. However, Hara notes that “those on the placebo also showed small score increases over time.”

Data published in Biomedical Research in 2019 also pointed to a small benefit. The study assigned 31 cognitively healthy people over age 50 to take either the supplement or a placebo. After 12 weeks, those taking lion’s mane showed improvement on the Mini Mental State Examination (MMSE) test.

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Still, Hara views the results with skepticism. “The MMSE is used to measure the severity of dementia,” she says. “It’s unclear how accurately it can measure cognitive function or benefits in healthy populations.” Importantly the supplement had no effect in two other cognitive tests that measured aspects of memory.

Another small study, published in 2020 in Frontiers in Aging Neuroscience, suggests that lion’s mane may improve some aspects of dementia. In the study, 41 people over age 50 with Alzheimer’s disease took the supplement enriched with a form of erinacine or a placebo for 49 weeks. Afterwards, those taking lion’s mane had improved scores on a test designed to measure the ability to carry out activities of daily living.

“These include things like being able to brush your teeth, get dressed, or take a bath in a more independent manner,” Hara says. However, there was no difference between the participants on the supplement and those taking the placebo in tests of cognitive function or psychiatric symptoms.

Taken as a whole, Hara characterizes the data as inconclusive. “There haven’t been large trials that looked at people for long periods of time with measures that are sensitive to detect cognitive changes,” she says. “Those are the types of studies that I hope to see.”

What are the risks?

Most study participants have tolerated lion’s mane supplements well, though some experienced stomach discomfort and diarrhea. Lion’s mane mushroom is generally recognized as safe when consumed as food. But safety information for long-term use of lion’s mane supplements is limited, Hara says. “Drug interactions with lion’s mane mushroom supplements have not been well-studied, so we don’t know which drugs lion’s mane may interact with and how,” she adds.

Another problem is that supplements in general are loosely regulated. That means there’s no guarantee that any lion’s mane supplement on the store shelf contains the levels of hericenones and erinacines that the bottle label claims.

“Occasionally supplements contain not much of the thing they claim to have in them or contain impurities,” says neurologist Steven DeKosky, M.D., who was an issue expert on AARP’s Global Council on Brain Health 2019 report, “The Real Deal on Brain Health Supplements.”

Eating lion’s mane mushrooms, themselves, which are commonly used in Asian diets, is one way to get potential benefits, though the effects haven’t been well studied. In addition to hericenones and erinacines, the mushroom — like many edible mushrooms — is rich in biotin, riboflavin, thiamin and folate. It also contains fiber and small amounts of potassium, magnesium, zinc, iron and copper. “It’s likely safe in quantities that are typically consumed in the diet in Asia or elsewhere,” Hara says. “A typical serving size of mushrooms, in general, is a cup for uncooked or half a cup of cooked.”

But outside of Asia, you may have trouble finding lion’s mane in its fresh forms. “Lion’s mane is not a mushroom that’s typically sold in the average U.S. supermarket, though you may find it in a farmer's market,” Hara says.

Beth Howard is a North Carolina–based health and lifestyle writer. She has written for dozens of publications, including U.S. News & World Report, The Wall Street Journal, The Washington Post, Prevention, Better Homes & Gardens and Reader’s Digest.