Lima beans are a good source of fiber and contain potassium, phosphorus, and small amounts of iron. A 1-ounce portion of the beans has less than 0.2 grams of fat (and no cholesterol), and 40 calories—a quarter of them from protein. An ounce of large limas has about 5.8 grams of carbohydrates, while one of baby limas has about 6.7 grams.
Limas are a good component of any healthy diet, but some limas—especially those grown outside the U.S.—can be poisonous. This is due to a compound called phaseolunatin, a cyanogenic glycoside that breaks down into hydrogen cyanide when the bean's cells are damaged. Limas, even domestic ones, should never be eaten raw—but, properly cooked, they pose no health danger.
A more realistic concern about limas is their comparative indigestibility. But that can be remedied: Place a pound of the beans in a pot large enough to accommodate them plumped up 2 1/2 times. Add 6-8 cups of cold water, and soak for at least 6 hours before cooking. Another method is to bring beans and water (10 cups of water to a pound of beans) to a boil, and continue boiling for 3 minutes; then cover and set aside for 1-4 hours before cooking. In either case, discard the soaking water and rinse the beans before cooking. Still another solution is a product called Beano; just put a few drops on your tongue along with your first bite of beans.