Author: Winston Craig, MPH, PhD, RD.
Mushrooms have been used for thousands of years both as food and for medicinal purposes. They are often classified as a vegetable or a herb, but they are actually fungi. While there are over 14,000 mushrooms, only about 3,000 are edible, about 700 have known medicinal properties, and fewer than one percent are recognized as poisonous.
Many people enjoy going to the woods to pick their own mushrooms. However, identifying mushrooms can be a real challenge. The color, shape and size of the fruiting body can vary tremendously. It is important to properly identify the mushroom that is collected, so as to avoid a poisonous species.
Today, mushrooms are enjoyed for their flavor and texture. They can impart their own flavor to food or take on the flavor of other ingredients. Their flavor normally intensifies during cooking, and their texture holds up well to usual cooking methods, including stir-frying and sauteing.
It is popular to add mushrooms to soups, salads, and sandwiches, or to use them as an appetizer. They also add an appealing touch to vegetable-based casseroles and stews. In the US, mushroom extracts are increasingly being used in nutraceutical products and sports drinks.
Mushrooms contain about 80 to 90 percent water, and are very low in calories (only 100 cal/oz). They have very little sodium and fat, and 8 to 10 percent of the dry weight is fiber. Hence, they are an ideal food for persons following a weight management program or a diet for hypertensives.
Mushrooms are an excellent source of potassium, a mineral that helps lower elevated blood pressure and reduces the risk of stroke. One medium portabella mushroom has even more potassium than a banana or a glass of orange juice. One serving of mushrooms also provides about 20 to 40 percent of the daily value of copper, a mineral that has cardioprotective properties.
Mushrooms are a rich source of riboflavin, niacin, and selenium. Selenium is an antioxidant that works with vitamin E to protect cells from the damaging effects of free radicals. Male health professionals who consumed twice the recommended daily intake of selenium cut their risk of prostate cancer by 65 percent. In the Baltimore study on Aging, men with the lowest blood selenium levels were 4 to 5 times more likely to have prostate cancer compared to those with the highest selenium levels.
The most commonly consumed mushroom in the United States is Agaricus bisporus or the white button mushroom. A. bisporus has two other forms – Crimini or brown mushrooms with a more earthy flavor and firmer texture, and Portabella mushrooms with a large umbrella-shaped cap and meaty flavor.
All three mushrooms, but especially the fresh button mushrooms, possess substances that inhibit the activity of aromatase (an enzyme involved in estrogen production), and 5-alpha-reductase (an enzyme that converts testosterone to DHT). The latest findings show that white button mushrooms can reduce the risk of breast cancer and prostate cancer. An extract of white button mushrooms decreased cell proliferation and decreased tumor size in a dose-dependent manner. The chemoprotective effect can be seen with an intake of about 100 grams (3.5 ozs) of mushrooms per day.
Shiitake mushrooms have been used for centuries by the Chinese and Japanese to treat colds and flu.Lentinan, a beta-glucan isolated from the fruiting body of shiitake mushrooms, appears to stimulate the immune system, help fight infection, and demonstrates anti-tumor activity.