Mushrooms are an excellent source of B vitamins, selenium, and potassium. These important vitamins and minerals help to break down proteins, fats, and carbohydrates. Mushrooms protect cells from damage that might lead to heart disease and high blood pressure. Mushrooms are one of the lone plant sources of vitamin D, a vitamin that contributes to bone health, building your immune system, and regulating cell growth. Mushrooms are a low calorie food because they are made up of 90% water. They are also fat-free, cholesterol-free, low in sodium, and full of fiber. Summary of Mushroom Key Findings from the Mushrooms and Health Summit Mushrooms have a unique nutrient composition: naturally low in calories, fat and cholesterol, they’re the only source of vitamin D in the produce aisle; provide B vitamins and potassium (8% DV); and are a valuable source of micronutrients and antioxidants such as ergothionene and selenium. Mushrooms, when substituted for meat ...