Lentils are nutrient-dense legumes rich in polyphenols, iron, calcium, magnesium, fiber and protein. Whether they are brown, green, black or red, these tiny gems can do everything from protect against heart disease to prevent congenital disabilities. Simple to cook, they don't require soaking like beans and are easy to incorporate into soups and salads. Lentils are also an economical protein source as meat is more expensive, has a shorter shelf life and is also full of saturated fat with no fiber. Swap lentils in for any recipe that calls for ground meat. Plus, a bag of lentils goes a long way as dry lentils tend to double in volume when cooked.