The Mushrooms Safe to Eat Raw

Ergothioneine, the so-called longevity vitamin, is largely heat stable, which means it is not destroyed when mushrooms are cooked. This is good news, because it’s best not to eat certain types of mushrooms raw; there’s a toxin in some cultivated mushrooms called agaritine, a natural toxin, to which we should minimize our exposure. Thankfully, the toxin is destroyed by cooking. Just thirty seconds in the microwave wipes out more than half of the agaritine in fresh mushrooms. Freezing can also get rid of most of it, but drying does not. So, if you put dried mushrooms in your soup, it’s best to boil them for at least five minutes. Though baking on a pizza may only eliminate about a quarter, one can take solace in the fact that no association between mushroom consumption and cancer was found in a study of two large Harvard cohorts.

Note, agaritine is only found in Agaricus mushrooms, like white, cremini, and portobello (which are all actually the same mushroom, just at different stages of maturity). So, eating oyster mushrooms raw is fine, though eating raw or undercooked shitake mushrooms can cause something else, called shiitake mushroom flagellate dermatitis. Flagellate as in flagellation, whipping or flogging: you can break out in a rash that makes it look as if you’ve been whipped. It’s thought to be caused by a compound in shitake mushrooms called lentinan, but because heat denatures it, it only seems to be a problem with raw or undercooked shitakes. Now, it’s rare; only about 1 in 50 people are even susceptible. And, it goes away on its own in a week or two. Interestingly, it can strike as many as 10 days after you eat them, which is why people may not make the connection. One poor guy suffered on and off for 16 years without a diagnosis. Bottom line? Cook your shiitakes.

Morel mushrooms are another special case. They should also be cooked, though they may react with alcohol even after cooking. So, don’t eat raw morels, don’t serve alcohol at a meal with even cooked morels, and don’t eat too many. Out of an abundance of caution, I would also recommend avoiding all wild-foraged mushrooms, given the potentially fatal consequences of misidentification.