2 Mushroom Pioneers Now Arguing Over What a Mushroom Is

Two pioneers of the mushroom supplement world, Paul Stamets and Jeff Chilton, are embroiled in a dispute over a basic but critical question in their field: What counts as a "mushroom"? The two, who co-authored the 1983 guide The Mushroom Cultivator and helped popularize mushroom growing, are now rivals, each running his own supplement company, per the Los Angeles Times. Stamets' Fungi Perfecti uses mainly mycelium—the vegetative part of the fungus that lives below the ground—in its products, while Chilton's Nammex focuses on the aboveground "fruiting body," the toadstool-shaped part most people recognize as a mushroom.

The debate matters because mushroom supplements are a booming business, with products marketed for brain and gut health, and phrases like "immune support" and "digestive health" common on labels. The disagreement centers on whether mycelium should be called a mushroom and whether it contains the same beneficial compounds as the fruiting body. Chilton claims many mycelium-based supplements are mostly grain starch, not mushrooms, and lack important compounds like beta-glucans. Stamets argues that mycelium offers its own benefits and that excluding it from the definition is misleading. Their feud has even drawn in the FDA, with Chilton pushing for stricter labeling.

The science remains unsettled: Some researchers say mycelium can be produced more safely and at scale, while others note the long history of the fruiting body's use in traditional medicine. Meanwhile, supplement companies are split roughly in half over which part to use, and consumers may not always know exactly what they're getting. The Washington Post details other ways that mushroom use has exploded, with them being used in everything from textiles and packaging to nonalcoholic beverages. In Australia, meanwhile, there's some commotion over an $80,000 mycelium bench that the nation's education department purchased for a New South Wales public school, per Sky News. (This content was created with the help of AI. Read our AI policy.)