Mycelium: What It Is and Why It's in Your Protein

Mushrooms have roots. Sort of. The mushroom you see is only the fruit. Underneath is mycelium, and it does most of the work.

What is mycelium?

Mycelium is the root-like body of a fungus. It's made of microscopic threads called hyphae that branch out through soil, wood or grain and form a connected web. That web takes in water and nutrients and moves them where the fungus needs them.

Mycelium is the long-lived part of a fungus. The mushroom, called the fruiting body, only shows up when conditions are right for it to release spores.

Fruiting body vs. mycelium

• Mycelium: the web of fine threads, usually hidden underground or inside wood. Think roots.
• Fruiting body: the cap and stem you'd recognize at a market. Think fruit.

Both show up in food. Some products use one, some use the other, and some use both. A good label tells you which.

What mycelium does in nature

Mycelium is one of nature's recyclers. It breaks down fallen leaves, dead wood and other organic matter and returns nutrients to the soil. Many fungi also connect with tree roots underground, trading nutrients with them. Researchers sometimes call these networks the "wood wide web."

Mycelium in your kitchen

You've probably eaten food made with mycelium without knowing it. Tempeh is soybeans bound together by mycelium. Koji, a fungus grown on rice, is behind soy sauce, miso and sake. Fermentation with fungi is an old idea.

Why it's in your protein

In MycoProtein, Shiitake mycelium ferments our pea and rice protein, the way a starter works on sourdough. Then we add four more mushrooms: Lion's Mane, Reishi and Turkey Tail fruiting bodies, plus Chaga mycelium. All five are 100% USA-sourced.

Want the full lineup? Meet all five in Mushroom 101.