Yes, mushrooms are naturally gluten-free. Some mushrooms may be grown in dirt padded with wheat or rye straw, but they won’t absorb gluten by touching the dead plants—just wash the mushrooms thoroughly as you would with any produce.
What are Mushrooms?
Mushrooms are a group of fungus, neither plant nor animal. There are many kinds of edible mushrooms, of different sizes, tastes, and textures. People who do not eat meat often use mushrooms as a substitute—portabella burger, anyone?
Mushrooms are low-calorie and high in nutrients like potassium, copper, and B vitamins. They make a great addition to any diet!
Mushrooms and Cross-Contact
Some mushrooms may be in contact with gluten-containing grains during the growing process. Spores (mushroom “seeds”) are stored in a mixture of sawdust, grain, or agar. This mixture is added to cardboard, dirt, wood, or a straw substrate, then dampened. Mushrooms can be harvested after a few weeks to a few months.
The straw substrate some mushrooms grow on can be made from hay or millet, which is gluten-free, or from wheat or rye, which are not gluten-free. Different cultivators may use different substrates, so if you are particularly concerned, you may want to call the mushroom farmer to ask about the substrate they use.
Some mushrooms grow better on wheat than other substrates. According to a 2025 research review, the edible species below do well when grown on wheat straw:
- Oyster mushrooms (pleurotus ostreatus)
- Turkey tails (trametes versicolor)
- Reishi mushrooms (ganoderma lucidum)
Despite sometimes growing near gluten-containing plants, there is no evidence that mushrooms absorb gluten. The FDA allows mushrooms grown on wheat substrate to be labeled gluten-free. If there were any gluten on mushrooms from physical contact, washing them thoroughly should be enough to remove it, the same way washing a cucumber or apple would remove gluten.
Should I eat Mushrooms if I’m Gluten-Free?
Mushrooms can be a safe and healthy addition to the gluten-free diet. As with most produce, it’s best to wash mushrooms before eating. If you are particularly worried about cross-contact, contact the manufacturer to ask more about their cultivation process.