Although considered a vegetable, mushrooms are neither a plant nor an animal food. They are a type of fungus that contains a substance called ergosterol, similar in structure to cholesterol in animals. Mushrooms contain protein, vitamins, minerals, and antioxidants. These can have various health benefits. The antioxidant content in mushrooms may help preventTrusted Source lung, prostate, breast, and other types of cancer, according to the National Cancer Institute.