Leeks are closely related to onions—as the similarity in flavor shows—and are distant cousins of asparagus. All three are members of the lily family.
Although leeks probably originated in warm regions of Asia or the Mediterranean, they are now intensely cultivated in temperate to cool climates, particularly in Northern Europe where they are a favorite. In Wales, where leeks are a national symbol, men parade in the streets with leek-bedecked hats on special holidays.
Leeks are surprisingly nutritious, providing an appreciable amount of minerals and fiber together with plenty of vitamin C. A half cup of chopped, boiled leeks contains only 15 calories but 25mg of vitamin C, as well as 16mg of calcium and a small amount of niacin.
Vegetables in the allium group (leeks, onions, shallots, scallions, chives, garlic) may have a protective effect against cancer, particularly gastric cancer, diabetes and heart disease, and like onions, leeks may help to lower cholesterol. Much of its therapeutic effect comes from its sulfur-containing compounds such as allicin. As allicin digests in the body, it produces sulfenic acid, a compound that neutralizes dangerous free radicals faster than any other known compound.
Leeks are most commonly used to add flavor, particularly to soups and stews. They are delicious in salads, vegetable dishes and quiches. But leeks have a milder, sweeter flavor than onions and a crunchy texture when cooked, which is why they are also delicious served on their own.
Excerpts from Foods that Harm Foods That Heal, The Reader’s Digest Association, Inc., ©1997, 212, 213.