Nutritional value of mushrooms
Mushrooms are a light and low-fat food
Fresh mushrooms are a light food consisting mostly of water (85–90%), and have an average energy content of only 25 kcal/100 g. Their fat content is only about 0.5 g/100 g. One hundred grams of mushroom contain about two grams of protein, and some species of mushroom have a higher protein content and a richer variety of amino acids than many vegetables. Aside from glucose, mushrooms contain trehalose (mushroom sugar), which can sometimes cause symptoms similar to lactose intolerance if not absorbed by the digestive system.
Mushrooms are rich in fibre, vitamins, minerals and trace elements
Mushrooms are a good source of fibre and contain 1.5–6 grams of insoluble fibre per one hundred grams. They supply moderate amounts of vitamins A, B, and D. Of the forest mushrooms, Chanterelles and Trumpet Chanterelles are rich in vitamin D2. Trumpet Chanterelles contain approximately 15,4 µg/100 g of vitamin D, and Chanterelles approximately 5.8 µg/100 g, whereas the recommended daily allowance for adults in Finland is 7.5 µg. Milkcaps also contain moderate amounts of vitamin D, approximately 5.5 µg/100 g. Chanterelles, as their golden colour suggests, also supply plenty of carotenoids, which are precursors of vitamin A. Of the B vitamins, mushrooms are especially rich in vitamin B2 (riboflavin) and vitamin B3 (niacin).
An important nutritional property of mushrooms is their high content of minerals and trace elements, higher than that of grains or garden plants. In the wild, mushrooms are good at extracting nutrients from the growth medium. They are especially rich in potassium, iron, zinc, and selenium. They contain only small amounts of sodium, so they are suitable also for people who have to watch their blood pressure.
Cooking affects nutritional content
When preparing foods with mushrooms, one should keep in mind that the cooking method can greatly affect the nutritional value in the end. The calorie content of mushrooms is increased by frying them in fat or adding cream, whereas if they are simply chopped up or fried in a small amount of vegetable oil, they are suitable even for someone on a diet. Steeping or boiling mushrooms destroys some of their minerals and vitamins. They should not be boiled unnecessarily if they are not a particular species that has to be processed in this way.