Lion's Mane

What lion's mane actually does in your brain

Lion's mane (Hericium erinaceus) is an edible mushroom with a shaggy white appearance that's been used in traditional Chinese and Japanese medicine for centuries. What makes it interesting for longevity science isn't folklore, though. It's the fact that two families of compounds in this mushroom, hericenones and erinacines, can stimulate production of nerve growth factor (NGF) in the brain ^[1]. NGF is a protein your neurons need to survive, grow, and form new connections. Without enough of it, nerve cells deteriorate, which is exactly what happens in aging brains and neurodegenerative conditions like Alzheimer's.

Erinacines are especially noteworthy because they're small enough to cross the blood-brain barrier, meaning they can reach the central nervous system after oral consumption ^[2]. This isn't true of most supplements marketed for brain health.

What the human studies show

The most-cited human trial is Mori et al. (2009): 30 older adults with mild cognitive impairment took 3 grams of lion's mane daily for 16 weeks. Cognitive test scores improved significantly compared to placebo. But here's the catch: the benefits disappeared within four weeks of stopping supplementation ^[3]. That tells us lion's mane doesn't permanently rewire your brain. It needs to be taken continuously to maintain effects.

A 2023 pilot study at Northumbria University tested 1.8 g daily in 41 healthy younger adults (ages 18-45). Participants reacted faster on cognitive tasks after a single dose, and showed a trend toward lower stress after 28 days of use ^[4]. A 2024 trial using erinacine A-enriched extract reported improved cognitive scores after 49 weeks in adults over 50 with early Alzheimer's symptoms ^[5].

That said, sample sizes across all human trials remain small (30-50 participants), and the 2025 systematic review by Frontiers in Nutrition notes that overall evidence is still mixed ^[6]. Lion's mane isn't a proven cognitive enhancer on the level of, say, regular aerobic exercise. But among mushroom-derived supplements, it has the strongest clinical data.

Beyond the brain: gut health and inflammation

Lion's mane isn't just a brain supplement. Animal and lab studies show it reduces inflammatory markers like TNF-alpha and IL-6, and may protect against ulcerative colitis by calming gut inflammation ^[7]. Its polysaccharides and beta-glucans act as prebiotics, feeding beneficial gut bacteria. Since gut health and brain health are connected through the gut-brain axis, these effects may contribute to the cognitive benefits researchers observe.

Early research also suggests immune-modulating properties. The beta-glucans in lion's mane activate macrophages and natural killer cells, your immune system's first responders. This is consistent with what we see from other medicinal mushrooms like reishi and turkey tail, though lion's mane research in immunology is less advanced.

Choosing and dosing lion's mane supplements

The fruiting body (the visible mushroom) and the mycelium (underground root network) contain different bioactive compounds. Fruiting bodies are richer in hericenones, while mycelium contains erinacines. Many cheap supplements use mycelium grown on grain, which means the final product is mostly grain starch with trace amounts of active compounds. Look for extracts that specify beta-glucan content (ideally above 25%) and state whether they use fruiting body, mycelium, or both.

Clinical trials have used doses between 1 and 3 grams daily, typically for 8 to 16 weeks before assessing results. Starting with 500 mg and increasing gradually is reasonable if you want to check for digestive tolerance first. Side effects are rare and mild, mostly limited to stomach discomfort. People with mushroom allergies should avoid it entirely, and those on blood-thinning or diabetes medications should consult a doctor, since lion's mane may affect blood clotting and blood sugar levels ^[6].