Lentils are an excellent source of folate.They are also a very good source of dietary fiber, copper, phosphorus and manganese. Additionally they are a good source of iron, protein, vitamin B1, pantothenic acid, zinc, potassium and vitamin B6. Lentils are still low in calories and contain virtually no fat. One cup of cooked lentils only contains about 230 calories, but still leaves you feeling satisfied.