What’s the difference between mushrooms and mycelium in supplements?

Why This Question Comes Up

On a bottle, the word “mushroom” can mean different things. Sometimes it means the fruiting body you recognize. Sometimes it means the mycelium.

Sometimes the mycelium is grown on grain and the grain is milled in, so part of what you are buying is cereal starch. Other times it refers to sugars collected from a tank where the fungus was grown in liquid. Because supplement labeling is not fully standardized, two products that both say “mushroom” can contain very different materials.

Confusion grows when ingredient panels use different numbers. One label might list beta-glucans, a cell-wall fraction. Another might list only “total polysaccharides,” which can also count grain starch in mycelium-on-grain materials. In practice, shoppers rely on brands that clearly state the part used (mushroom or mycelium), how it was grown (wood, grain, or liquid), how it was prepared (powder or extract), and which number was tested (beta-glucans, not just totals).

Key Terms

• Mushroom (Fruiting Body): The visible cap and stem or bracket that releases spores.
• Mycelium: The underground network of fine threads that feeds the fungus.
• Mycelium on Grain (MOG): Mycelium grown across a cereal (for example rice or oats) and milled together with that grain.
• Beta-Glucans: Fungal cell-wall polysaccharides often used as a potency marker.
• Alpha-Glucans: Starches or glycogen; in MOG, much of this comes from the grain.

How Mushrooms for Supplements Are Grown

How a fungus is grown shapes what ends up in the jar and which numbers appear on the label.

Fruiting Bodies on Wood or Sawdust. Cultivated on sterilized wood or sawdust blocks until caps and stems form, then harvested and dried. The tissue is wall-dense, and beta-glucans commonly appear in measurements.

Mycelium on Wood or Sawdust. Harvested as fungal biomass without grain. It is still largely fungal wall material, though the profile varies with culture time and conditions.

Mycelium on Grain (MOG). The fungus colonizes a sterilized cereal; the entire mass—grain plus mycelium—is dried and milled. “Total polysaccharides” can look high because grain starch (alpha-glucans) is counted alongside fungal polysaccharides.

Liquid Culture (Broth). Mycelium grows in tanks and may release exopolysaccharides into the liquid. Polysaccharides recovered from the broth are not the same as cell-wall beta-glucans and may be measured with different tests.

Anatomy and Reproduction: How a Fungus Is Built and Why It Matters

The Two Main Parts

• Fruiting Body (the “Mushroom”): The spore-releasing structure you can see: caps with gills or pores, brackets on logs, puffballs, or truffles underground. It is tightly packed tissue with thick cell walls.
• Mycelium (the “Network”): A hidden web of threads that spreads through wood or soil, releases enzymes to digest food outside the body, and absorbs nutrients.

How Mushrooms Reproduce

Mushrooms are the reproductive structures of fungi, built by the hidden network of mycelium. The mycelium grows through soil, wood, or other material, absorbing nutrients as it spreads. When temperature, moisture, and nutrients align, the mycelium organizes some of its threads into a dense structure: the fruiting body we see as a mushroom.

That fruiting body’s job is to release spores, which act like seeds. Spores drift on air currents, land in new environments, and can germinate into fresh mycelium if conditions allow. After releasing spores, the fruiting body breaks down, but the underground mycelium remains alive and can produce new mushrooms again when the environment is favorable.

Why Structure Changes Composition

• Wall Density: Fruiting bodies are compact and wall-rich, so per gram they usually carry more beta-glucans.
• Location of Compounds: Some small molecules concentrate in outer tissues of the fruiting body; the mycelium invests more in growth and enzyme production.
• Food Source Imprint: Mycelium grown on grain is harvested with that grain, so part of the powder is ordinary starch. Mycelium grown on wood or in liquid culture carries a different profile.

What This Means in Supplements

• If an ingredient is fruiting-body based, expect a wall-dense material where beta-glucans are often the focus.
• If an ingredient is mycelium based, what you get depends on where it was grown:
  • On wood or sawdust: mostly fungal biomass with wall polysaccharides.
  • On grain (MOG): a mix of fungal material and grain starch.
  • In liquid culture: may include polysaccharides from the broth, which are not the same as wall beta-glucans.

Key Takeaway

In practice, the word “mushroom” can mean fruiting body, mycelium, mycelium on grain, or fermentation polysaccharides. To evaluate supplements, match the part used and how it was grown, then look for a stated percent of beta-glucans to compare products fairly.