The leek, or Allium ampeloprasum porrum, is a slender herb with a small bulb and a long cigar-shaped stem composed of concentric layers of overlapping leaves. Pleasant and sweet-flavored, leeks are related to onions, garlic and shallots.
Low in calories, leeks are an excellent source of the flavonoid kaempferol, which helps to protect the linings of the blood vessels from damage. Leeks contain significant amounts of antioxidants, which are antibacterial, antifungal and antiviral in nature. Leeks are abundant in vitamin K (essential for blood coagulation), folic acid (essential for DNA synthesis) and vitamin A (essential for good vision). Small amounts of minerals such as iron, calcium and magnesium are also present in the stalks.