Within the Allium family of vegetables—which includes garlic, onions, and shallots—leeks are oft overlooked cousins. Though ubiquitous in French, Belgian, and Dutch cooking, leeks in American kitchens tend to be relegated to potato leek soup, if anything. Perhaps it's their rangy appearance (they can grow up to two feet long and two inches thick) or cumbersomeness (the dark, ribbon-like leaves must be removed) that causes American cooks to shy away. But those who do venture to trim leeks and incorporate them into their cooking are in for a rich reward. Not only do leeks have a sweeter, milder flavor than onions and garlic, they also have all the health benefits of their more pungent counterparts and then some.
Leeks and their brethren have multiple benefits for cardiovascular health. Some studies show that Allium vegetables can lower LDL ("bad") cholesterol and raise HDL ("good") cholesterol, an important balance for maintaining healthy arteries. Consuming these vegetables on a regular basis can guard against the build-up of arterial plaque, blood clots, and high blood pressure, all significant risk factors for heart attack and stroke.
Allium vegetables contain compounds called allyl sulfides, which have been shown to protect cells from cancer-causing hormones and chemicals. Studies have demonstrated their particular effectiveness in preventing colon cancer. Leeks, with their gentler taste and aroma, do contain less of these sulfides than their more bitter relatives, garlic and onions, so you'll need to consume more to gain equal benefits. Then again, it's more pleasing to enjoy a side of subtly flavored leeks than a serving of breath-killing garlic.
Full of Minerals
Leeks are also rich in the flavonoid kaempferol; the extensive Nurses' Health Study conducted at Harvard University showed that women whose diets were highest in kaempferol had a 40 percent reduction in the risk of ovarian cancer. Other nutrients prevalent in leeks include manganese, vitamin B6, vitamin C, folate, and iron. These vitamins and minerals work together to help stabilize blood sugar absorption and metabolism, making leeks a healthy choice for dieters and diabetics alike.
Leeks support healthy digestion by promoting the growth of "friendly" bacteria in the gut. They are one of the few foods that contain prebiotics—carbohydrates that are indigestible to us but serve as fuel for good bacteria in the digestive tract. These probiotic bacteria keep invading pathogens at bay, fortifying our immune systems and keeping our digestive processes running smoothly.
Though the white and light green parts of the leek are especially tender when cooked, leeks have long been a symbol of strength. The Roman emperor Nero is known to have eaten leeks on a daily basis to fortify his voice. Welsh soldiers attributed their potency in battle against the Saxons in 1620 to leeks; they wore them in their caps to differentiate themselves from their enemies. With their beneficial impact on cardiovascular and digestive health as well as their potential to fight cancer, leeks deserve to be more than just wallflowers in American kitchens.