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February 26, 2010 | Comments: 3

Mushrooms: Food, Medicine, or Poison?

Some mushrooms, particularly those with a long history of use in Asia, are thought to have medicinal qualities. Others have adverse effects or are outright poisonous. Here's how to make room for mushrooms.

Though mushrooms are fungi—neither plant nor animal—they are usually regarded as vegetables. Button mushrooms are most common but specialty mushrooms, such as chanterelles, enoki, maitake, and shiitake, are increasingly available and affordable, thanks to year-round indoor cultivation.

The best reason to eat mushrooms is for their flavor, which becomes especially savory when they are cooked. Called umami, the flavor comes from glutamic acid, a natural version monosodium glutamate. But mushrooms are also an overlooked source of nutrients, including B vitamins, copper, iron, potassium, and selenium. They have some fiber, yet few calories. Fresh cremini (brown button) and portabello (fully grown cremini) mushrooms have similar nutrition as white button mushrooms but more flavor. Canned mushrooms lose some nutrients in processing.

Potion . . . Some mushrooms, particularly those with a long history of use in Asia, are thought to have medicinal qualities due to their polysaccharides and other compounds. Shiitake and maitake mushrooms have shown immune-boosting and anti-tumor activity in lab studies, and white button mushrooms may inhibit the activity of enzymes implicated in breast and prostate cancer. It’s questionable how much benefit you get simply by eating mushrooms—or by taking capsules of mushroom extract—but scientists are isolating mushroom compounds for potential use as medicines.

. . . or poison? Like all plant foods, raw mushrooms contain natural substances that may have adverse effects. Some mushrooms are poisonous. But even the hydrazines in white button mushrooms can, in large amounts, cause cancer in lab animals. While most people don’t eat enough raw mushrooms for this to be a problem, if you do eat mushrooms often or in large amounts, eat them cooked, since cooking destroys the substances (as does drying). Cooking also breaks down the fibrous cell walls in mushrooms so that nutrients are more available to the body, and destroys some nutrient-blocking compounds.

Mushroom management

• Unless you’re an expert, don’t eat mushrooms you find in the wild—it’s easy to confuse a highly toxic wild mushroom with an edible one. 

• Refrigerate mushrooms in a paper bag or container that allows air to circulate, but don’t wash them until you are ready to use them. Then, wipe them gently with a damp cloth or soft brush, or wash them quickly under running water. Trim any woody stems.

• Cook mushrooms in a little olive oil, water, or broth. A whole grilled portabello is a meaty substitute for a beef burger. Small amounts of dried mushrooms, reconstituted in hot water, add concentrated flavor to soups, stews, and sauces. 

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