The National Institutes of Health says that women over 50 and all adult men need at least 8 milligrams of iron a day. Women aged 19 to 50 need 18 milligrams, and pregnant women need 27 milligrams. A cup of lentils or a cup of white beans will both give you 6.6 milligrams of iron, while red kidney beans provide 5.2 milligrams.
These same beans are relatively low in calories — about 230 calories for a cup. Lentils will fill you up with 16 grams of fiber, and white beans and kidney beans have 11.3 grams and 13 grams, respectively. Let’s not forget the protein in beans. A cup of beans can provide almost the same amount of protein as a scoop of protein powder.
Beans are great sources of potassium to keep your blood pressure under control. The American Heart Association suggests men get 3,400 milligrams of potassium and women get 2,600 milligrams a day. A cup of white beans can get you well on your way to reaching your potassium needs with 1,000 milligrams. Lentils and red kidney beans aren’t far behind, with about 700 milligrams.