The short answer
The fruiting body is the mushroom itself and is rich in hericenones and beta-glucans. Mycelium is the network of threads it grows from and holds most of the erinacines. Mycelium grown on grain is often sold with the grain still in it, so much of the powder can be starch. Most human trials used fruiting body.
On this page
What is the difference between fruiting body and mycelium?
The fruiting body is the part you can see and cook: the shaggy white mushroom. Mycelium is the mass of fine threads that grows through wood, or through whatever a grower feeds it, and produces the fruiting body when conditions are right. Both are lion’s mane, but they are not the same material.
Which compounds are in each part?
The two parts carry different compounds, which is why the choice matters:
| Fruiting body | Mycelium | |
|---|---|---|
| Main signature compounds | Hericenones | Erinacines, especially erinacine A |
| Beta-glucans | High, around 17% of dry weight in one analysis | Varies widely; depends on how it was grown |
| Starch | Very little (under 1% alpha-glucan in the same analysis) | Can be high if grown on grain and sold with it |
| Used in trials | Most of them (Mori 2009, Nagano 2010, Saitsu 2019, Grozier 2022, La Monica 2023, Surendran 2025) | Li 2020, plus blends in Vigna 2019 and Evans 2026 |
Erinacines are the compounds with the strongest nerve growth effects in animal studies (see lion’s mane for nerve damage), so mycelium is not worthless. The trial with the longest follow-up, in people with mild Alzheimer’s disease, used mycelium standardised to its erinacine A content. That product was grown in liquid culture, not on grain, and its maker tested it for erinacine A.
Why does grain matter?
Many mushroom supplements, especially from the US, are made by growing mycelium on sterilised oats, rice or other cereal, then drying and grinding the whole block. The label may say “mycelium” or “myceliated grain”, or simply “organic lion’s mane”. What it does not say is how much of the powder is still grain.
Grain is mostly starch. Analysts measure starch as alpha-glucan, and real mushroom fibre as beta-glucan. A study of chaga supplements made this way found they were rich in starch and chemically quite unlike the real mushroom, and the same production method is used for lion’s mane. Starch is harmless, but you are paying mushroom prices for porridge.
How can you tell from the label?
Look for three things:
- Which part is used. “Fruiting body” or “100% fruiting body” is the clearest. If it says mycelium, look for how it was grown: liquid (submerged) fermentation is better than “on grain” or “myceliated oats”.
- A beta-glucan figure, and ideally an alpha-glucan figure. The standard enzyme test (the Megazyme method) measures both. A label that reports only “polysaccharides” can include starch, because starch is a polysaccharide too.
- No grain filler listed. Oats, brown rice or “grain” in the ingredients list is a sign the mycelium was sold with its growing medium.
Our buying guide covers extract ratios, testing and UK labelling rules.
Keep reading
- Can you pick lion's mane in the UK? What the law says
Wild lion's mane is protected under the Wildlife and Countryside Act 1981. Why picking or selling it is an offence, and where to get it legally.
Common questions
Is mycelium lion's mane a scam?
Not always. Mycelium grown in liquid and then purified can be rich in erinacines, and one trial in Alzheimer's disease used it. The problem is mycelium grown on grain and sold without separating the grain, which can be mostly starch. A product should say how its mycelium was grown and give a beta-glucan figure.
What does 'myceliated grain' mean on a label?
It means mycelium was grown on a cereal such as oats or rice and the whole mix was dried and ground. You are buying the grain as well as the fungus, and the label usually cannot tell you how much of each.
How much beta-glucan should lion's mane powder have?
There is no legal standard. Laboratory analysis of lion's mane fruiting bodies has found beta-glucan levels around 17 percent of dry weight, so a product claiming far more than that is probably quoting a different test or a concentrated extract.
References
- McCleary BV, Draga A. Measurement of β-glucan in mushrooms and mycelial products. Journal of AOAC International, 2016.pubmed.ncbi.nlm.nih.gov
- Keerthana CS et al. Unveiling the glucan profile: a comparative study of lion's mane and shiitake mushrooms. Natural Product Research, 2026.pubmed.ncbi.nlm.nih.gov
- Windsor C et al. Comparative study of chaga (Inonotus obliquus) dietary supplements using complementary analytical techniques. International Journal of Molecular Sciences, 2025.pubmed.ncbi.nlm.nih.gov Found that mycelium-on-grain products were starch-rich; a different mushroom, but the same way of making supplements.
- Sweeney LC et al. Advances in enzymatic measurement of β-glucan in mushrooms, yeast, algae, and dietary supplements. Journal of AOAC International, 2026.pubmed.ncbi.nlm.nih.gov
- Li IC et al. Prevention of early Alzheimer's disease by erinacine A-enriched Hericium erinaceus mycelia: pilot double-blind placebo-controlled study. Frontiers in Aging Neuroscience, 2020.pubmed.ncbi.nlm.nih.gov
- Amen Y et al. Chemistry and bioactivities of erinacines from Hericium fungi. Journal of Natural Medicines, 2026.pubmed.ncbi.nlm.nih.gov
First published 3 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.