Dried fern is processed from fresh fern and is a common food, contraindicated for those who are allergic to fern. Fiddlehead fern contains a small amount of the class 2B carcinogen protofernoside, which should not be consumed in large quantities. Fiddleheads become dried ferns after being baked in the sun, so the nutrients of the two are the same, only the content is different. Every 100 grams of fern (dry) contains 302 kcal of energy, 79.7 grams of carbohydrates, 25.5 grams of crude fiber, 851 milligrams of calcium, 253 milligrams of phosphorus, 3 milligrams of vitamin C and other nutrients. Fiddlehead fern contains proto fern glycosides, which are class 2B carcinogens. Although its content is low, it should not be consumed in large quantities. Dried fern contains a variety of minerals and vitamins, moderate consumption can supplement the body with the required nutrients, which is conducive to good health. However, excessive consumption may increase the burden on the stomach and intestines causing indigestion, resulting in abdominal pain, diarrhea, vomiting and other discomforts.