Key takeaways
- Mycelium on grain is fungus grown through cooked grain, often dried and milled together.
- The finished product can contain a substantial proportion of grain starch.
- Starch (alpha-glucans) can inflate “polysaccharide” or “glucan” figures.
- Mycelium isn’t inherently bad; the issue is transparency about what’s in the product.
- Look for “mycelium”, grain ingredients and missing “fruiting body” on labels.
Many mushroom supplements on the market are not made from mushrooms in the everyday sense. They are made from mycelium, the thread-like part of a fungus, grown on grain. This article explains how these products are made, what ends up in them and how to tell if you’re buying one.
How it’s made
Growing mushrooms usually starts with spawn: sterilised grain that has been colonised by fungal mycelium. Mushroom farms use spawn to seed the logs, sawdust or straw on which fruiting bodies will grow.
Some supplement producers stop at the spawn stage. The fungus is allowed to grow through the grain, then the whole mass, mycelium and grain together, is dried and milled into powder. Products made this way are sometimes described as “myceliated grain”, “mycelial biomass” or simply “mycelium”.
What ends up in the product
Because the mycelium grows through the grain, and grain is largely starch, the finished powder can contain a substantial proportion of grain starch alongside the fungal material. How much depends on the producer and the process, and it is rarely stated on the label.
Why the starch matters
Starch is made of alpha-glucans. Fungal cell walls contain beta-glucans. Both are glucose chains, so testing that measures “total polysaccharides” or “total glucans” without separating them can make a grain-heavy product look richer in fungal compounds than it is. Methods that measure beta-glucans and alpha-glucans separately give a clearer picture. See Alpha-Glucans, Starch and What They Can Tell You and Beta-Glucan Testing Explained.
A fair perspective
Mycelium isn’t inherently bad. It is a genuine part of the fungus, and in some species it produces compounds found less in the fruiting body. Lion’s Mane erinacines are the best-known example. Mycelium can also be grown in liquid culture and separated from its growing medium, avoiding the grain issue.
The concern is transparency: a product sold simply as “Lion’s Mane” or “Reishi” that is largely grain isn’t what most people expect to be buying.
How to spot it on a label
- Look for “mycelium”, “myceliated”, “mycelial biomass” or “full spectrum”.
- Check the ingredients for brown rice, oats or another grain, sometimes listed as the growing medium.
- Be cautious of “polysaccharide” figures without a beta-glucan figure.
- If it doesn’t say “fruiting body”, ask.
Our approach
We don’t use grain-grown mycelium. Our tinctures are made from UK-grown fruiting bodies, and wild chaga from Finland, extracted in hot water and plant-derived ethanol. Read Fruiting Body vs Mycelium for the fuller comparison, or Why We Focus on Fruiting Bodies.
