Why the label is a problem
A mushroom supplement is the one product where the word "mushroom" on the package can mean a product containing almost no mushroom. The reason is legal: both a fruiting-body product and mycelium grown on grain count as "mushroom" supplements — and the latter is essentially a fermented grain substrate with an admixture of fungal tissue. In the US such products make up a significant share of the market; the Italian market analysis (we covered it in a separate article) showed the same picture in Europe.
The main fork: fruiting body vs mycelium
| Fruiting body | Mycelium on grain | |
|---|---|---|
| What it is | The mushroom itself — cap, stem | Vegetative tissue + substrate |
| β-glucans | 20–40% of dry mass | Usually lower, diluted by grain |
| Starch | Little | A lot (grain residue) |
| What was studied | Most clinical work | A minority (except Cs-4, certain mycelial strains) |
An important caveat: mycelium ≠ always bad. The legendary Cs-4 is a fermented mycelium, and it is what features in the cordyceps clinical work. The problem is not the word "mycelium" but an undiluted grain substrate sold as a mushroom.
The "polysaccharides" trap
Labels often say "30% polysaccharides" — sounds impressive. The catch: starch is also a polysaccharide. The colorimetric test for total polysaccharides (phenol–sulfuric acid) cannot tell a fungal β-glucan from grain starch. Mycelium on rice easily shows "60% polysaccharides", most of which is starch.
What to look for instead: the share of β-glucans stated separately. Serious manufacturers publish β-glucans and α-glucans separately — here α-glucans are mostly starch, and if their share is high while β-glucans are low, you are looking at mostly grain.
Label vocabulary
- Fruiting body — what you want for species whose active compounds concentrate in the fruiting body (reishi, shiitake, lion's mane).
- Mycelium / myceliated grain — mycelium; if it comes without the substrate and shares specified, read it as "grain".
- Full spectrum — a marketing term without a standard; usually means "we put in some of each, and we won't say in what proportions".
- Hot water extract — the standard for β-glucans; a dry mushroom powder without extraction gives poor bioavailability (the cell wall is chitinous).
- Dual extract — water + alcohol; relevant for reishi and chaga (triterpenes are not water-soluble).
- Extract ratio (8:1, 10:1) — useful, but only alongside β-glucans: a grain concentrate is still a grain concentrate.
Six red flags on a jar
- No "fruiting body" anywhere — but "myceliated brown rice/biomass" present.
- "Polysaccharides XX%" without a separate β-glucan line.
- No extraction type (hot water / dual) — probably just milled substrate.
- No Latin species name — a "forest mushroom complex".
- A tiny capsule dose at "100% natural" — 300 mg of blend per capsule is mushroom homeopathy.
- No raw-material data (country, substrate) and no lab tests (heavy metals for chaga and other bioaccumulators).
A home check: the starch test
The iodine test is a simple way to check for grain filler: a drop of iodine on the capsule contents. Intense blue-black staining = lots of starch = grain substrate. A pure fruiting body has almost no starch — the staining is faint. Not lab-grade precision, but a working filter.
What this changes for interpreting research
The practical benefit of reading the label: the cards in our research catalog always state what exactly was taken — fruiting body, extract, or fraction (maitake D-fraction, trametes PSP/PSK, Cs-4 mycelium). Compare "your jar" against the form used in the study, not against the mushroom's name: a D-fraction and cap powder are different things.