The Stamets Stack: What the Research Says About Psilocybin, Lion's Mane and Niacin

The Stamets Stack is the best-known microdosing formula in the world. It pairs a small amount of psilocybin mushroom with lion's mane, a non-psychoactive mushroom, and niacin, also called vitamin B3. Mycologist Paul Stamets popularised the idea and has filed patent applications on it, and today many microdose capsules are built around some version of the three.

So what does the research actually say? The honest answer is that each ingredient has been studied a little, the combination has been studied once in a large observational project, and nobody has yet run a placebo-controlled trial of the full stack. Here is what each piece of evidence shows.

This is general information, not medical advice, and none of these products is a treatment for anything.

What is in the stack

• Psilocybin mushroom, usually 50 to 150 mg of dried Psilocybe cubensis per capsule, well below the amount that causes a full experience.
• Lion's mane (Hericium erinaceus), a shaggy white culinary mushroom that contains compounds called hericenones and erinacines.
• Niacin (vitamin B3). Stamets has suggested that niacin's warm skin flush could help the other ingredients reach the body's extremities. That idea has not been tested.

Stamets also proposed his own schedule: four days on, three days off. Our guide to microdosing schedules compares it with the Fadiman protocol and others.

The largest study of stacking

In 2022, Joseph Rootman and colleagues, with Stamets among the authors, published a study in Scientific Reports that followed 953 people who microdosed psilocybin and 180 who did not, for about a month. Participants used a smartphone app to report their mood and complete simple tests.

• People who microdosed reported larger improvements in mood and mental health over the month than people who did not.
• In an exploratory analysis, older participants who combined psilocybin with lion's mane and niacin did better on a finger-tapping test of psychomotor speed than those who did not stack.

These are interesting findings, but read them with care. Participants chose to microdose and chose what to take, nobody received a placebo, and one of the authors is the person most associated with the formula. The study shows associations, not causes.

What happens when there is a placebo

When researchers do add a placebo, the picture changes. Two studies are worth knowing.

• In 2021, Balázs Szigeti and colleagues ran a "self-blinding" study published in eLife. Microdosers prepared their own real and placebo capsules without knowing which was which. Psychological measures improved over the study, but they improved about as much on placebo as on the real thing.
• In 2022, Federico Cavanna and colleagues gave 34 volunteers either about half a gram of dried psilocybin mushrooms or a placebo in a double-blind study, published in Translational Psychiatry. They found no clear difference between the two on creativity, wellbeing or mood measures.

Neither study tested lion's mane or niacin, and both were small. But they are a reminder that expectations play a large part in how microdosing feels, which is exactly why careful trials matter.

What we know about lion's mane

Lion's mane has a longer research history than the stack itself. In laboratory studies, its hericenones and erinacines stimulate production of nerve growth factor, a protein involved in the growth and maintenance of nerve cells. That is a cell and animal finding, not proof of anything in people.

Human studies are few and small.

• In 2009, Koichiro Mori and colleagues gave 30 Japanese adults aged 50 to 80 with mild cognitive impairment either lion's mane tablets or a placebo for 16 weeks. Scores on a cognitive test rose in the lion's mane group and fell back after they stopped taking it.
• In 2023, Holly Docherty and colleagues tested lion's mane in 41 healthy adults aged 18 to 45, published in Nutrients. People were slightly faster on one attention test an hour after a single serving, and after four weeks there was a trend towards lower stress that fell just short of statistical significance. The authors called the results tentative.

Lion's mane is generally well tolerated as a food, but people with mushroom allergies should avoid it.

How stacked capsules compare

Because nobody has settled on one formula, stacked capsules on the market differ quite a bit. These are four we carry, with what is in each capsule:

• Spore Wellness Cognitive Microdosing Capsules: the closest to the classic stack, with 100 mg Golden Teacher, 325 mg lion's mane, 25 mg niacin and a little organic ginger.
• Neuro Botanicals Brain Formula: a gentler take, with 50 mg Golden Teacher, 425 mg lion's mane dual extract and 25 mg niacin.
• DÖSE Neurogenesis No.3: 150 mg Golden Teacher with 300 mg of concentrated lion's mane extract and 50 mg acetyl-L-carnitine instead of niacin.
• Be Brilliant Booster: lion's mane, niacin and ginger with no psilocybin at all, for people who want the functional half of the stack on its own or prefer to pair it with a separate microdose.

If you would rather build your own stack, a plain capsule such as ARCHETYPE CLEAR, with 100 mg of Golden Teacher and nothing else, makes it easy to keep track of what you are taking. Our guide to reading a microdose label explains how to compare amounts across brands.

Who should skip it

Do not use psilocybin if you are under 19, pregnant or breastfeeding, or have a personal or family history of psychosis or bipolar disorder. Do not combine it with lithium. Antidepressants such as SSRIs can blunt the effects, and stopping one without your prescriber is its own risk. Read psilocybin and medications and our safety guide first.

Psilocybin is a controlled substance in Canada. This is not legal advice. See psilocybin in Canada.

The bottom line

The Stamets Stack rests on a reasonable idea and a small amount of evidence. Lion's mane has some encouraging early human data, the stack has one large observational study behind it, and placebo-controlled microdosing trials so far suggest expectations do much of the work. If you try it, start low, keep notes, and judge it by how you actually feel over weeks rather than by the claims on any label. A microdosing journal helps.

Sources

• Rootman et al. (2022), Psilocybin microdosers demonstrate greater observed improvements in mood and mental health at one month relative to non-microdosing controls, Scientific Reports
• Szigeti et al. (2021), Self-blinding citizen science to explore psychedelic microdosing, eLife
• Cavanna et al. (2022), Microdosing with psilocybin mushrooms: a double-blind placebo-controlled study, Translational Psychiatry
• Mori et al. (2009), Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment, Phytotherapy Research
• Docherty et al. (2023), The acute and chronic effects of lion's mane mushroom supplementation on cognitive function, stress and mood in young adults, Nutrients
• Cover photo: Hericium erinaceus (lion's mane) by Ken Kneidel, CC0, via Wikimedia Commons

This guide is general information, not medical or legal advice. If you have health questions, talk to a health professional.