Leeks

Leeks

With all those great flavonoids and sulfur-enriched nutrients, you should be eating leeks regularly! Leeks, like garlic and onions, belong to the Allium vegetable family. Leeks contain many of the same beneficial compounds as you will find in garlic and onions, as well. With all those great flavonoids and sulfur-enriched nutrients, you should be eating leeks regularly! Leeks, like garlic and onions, belong to the Allium vegetable family. Leeks contain many of the same beneficial compounds as you will find in garlic and onions, as well. 

Leeks are also related to shallots, and scallions. (Yum!) They have a very small bulb and a long white cylindrical stalk comprised of layers that flow into green, tightly wrapped, flat leaves. Cultivated leeks are usually about 12 inches in length and one to two inches in diameter and feature a fragrant flavor that is reminiscent of shallots but sweeter and more subtle.  With a more delicate and sweeter flavor than onions, leeks add a subtle touch to recipes without overpowering the other flavors that are present.  Although leeks are available pretty much year-round, they are in season from the fall through the early part of spring when they are at their best.

The flavonoids in leeks are most concentrated in the lower leaf and bulb portion of the stalk. The Flavonol Kaempferol, its premier flavonoid, ranks ahead of white onions in terms of their kaempferol content, but they still provide slightly less kaempferol than red onions. For other types of flavonoids, including quercetin, leeks appear to provide lower concentrations than most types of onions.

Leek History

Leeks enjoy a long and rich history, one that can trace its heritage back through antiquity. Thought to be native to Central Asia, they have been cultivated in this region and in Europe for thousands of years.  Leeks were prized by the ancient Greeks and Romans and were especially revered for their beneficial effect upon the throat. The Greek philosopher Aristotle credited the clear voice of the partridge to a diet of leeks, while the Roman emperor Nero supposedly ate leeks everyday to make his voice stronger. Fascinating, huh?

The Romans are thought to have introduced leeks to the United Kingdom, where they were able to flourish because they could withstand cold weather. Leeks have attained an esteemed status in Wales, where they serve as the country’s national emblem. The Welsh regard for leeks can be traced back to a battle that they successfully won against that Saxons in 1620, during which the Welsh soldiers placed leeks in their caps to differentiate themselves from their opponents! Today, leeks are an important vegetable in many northern European cuisines and are grown in many European countries.

Leek Nutrition

61 calories
Energy 255 kJ (61 kcal)
14 grams carbohydrates
1.5 grams protein
0.3 grams fat
1.8 grams fiber
3.9 grams sugar

47 micrograms vitamin K (59 percent DV)
1,667 IUs vitamin A (33 percent DV)
12 milligrams vitamin C (20 percent DV)
64 micrograms folate (16 percent DV)
.23 milligrams vitamin B6 (12 percent DV)
2.1 milligrams iron (12 percent DV)
28 milligrams magnesium (7 percent DV)
59 milligrams calcium (6 percent DV)
180 milligrams potassium (5 percent DV)
0.06 milligrams thiamine (4 percent DV)

Vitamin A equiv.
beta-carotene
lutein zeaxanthin (10%) 83 mg(9%) 1000 mg 1900 mg
Thiamine (B1) (5%) 0.06 mg
Riboflavin (B2) (3%) 0.03 mg
Niacin (B3) (3%) 0.4 mg
Pantothenic acid (B5) (3%) 0.14 mg
Vitamin B6 (18%) 0.233 mg
Folate (B9) (16%) 64 mg
Vitamin C (14%) 12 mg
Vitamin E (6%) 0.92 mg
Vitamin K (45%) 47 mg

Leeks Offer Great Cardiovascular Support

Due to the high Flavonoid Kaempferol content, leeks are found to help protect the blood vessel linings from damage. Interestingly, one of the mechanisms involved in this blood vessel protection may involve increased production of nitric oxide (NO), a naturally occurring gas that helps to dilate and relax the blood vessels, as well as decreased production of that asymmetric dimethylarginine (ADMA), a substance that blocks production of NO.

Often overlooked in leeks is their important concentration of the B vitamin folate. Folate is present in leeks in one of its bioactive forms (5-methyltetrahydrofolate, or 5MTHF) and it is present throughout the plant (including the full leaf portion, not only the lower leaf and bulb). While it’s true that we still get about 50% more 5MTHF from the bulb than the leaves, this distribution of folate throughout the plant makes leeks a cardioprotective food from top to bottom. (Folate is a key B complex vitamin for supporting our cardiovascular system, because it helps keep our levels of homocysteine in proper balance. Excessively high levels of homocysteine are a risk factor for many cardiovascular diseases.)

Also present in leeks are impressive concentrations of antioxidant polyphenols. These polyphenols play a direct role in protecting our blood vessels and blood cells from oxidative damage. The total polyphenol content (TPC) of leeks averages about 33 milligrams of gallic acid equivalents (GAE) per 100 grams of fresh edible portion (FEP). By contrast, the TPC of red bell peppers averages 27 milligrams; cherry tomatoes, 24 milligrams; and carrots, 10 milligrams. So even though leeks are less concentrated than some of their fellow allium vegetables in terms of total polyphenols (garlic provides about 59 milligrams GAE/100g FEP, and onions provide about 76 milligrams), they are still a highly valuable food in terms of these phytonutrient antioxidants and provide us with important cardiovascular benefits for this reason.

Other Health Benefits of Leeks

Unfortunately, leeks have received less research attention than their fellow allium vegetables (especially garlic and onions), and for this reason, there is less documentation of their likely health benefits. Given their substantial polyphenol content we would expect to see overlap with garlic and onions in terms of support for many health problems related to oxidative stress and chronic low-level inflammation. These health problems would include atherosclerosis, type 2 diabetes, obesity, rheumatoid arthritis, and allergic airway inflammation. We would also expect to see leeks providing measurable amounts of protection against several different types of cancer, mostly likely including colorectal cancer.

Preparation of Leeks

Many people are unfamiliar with how to cook or prepare leeks. We recommend cutting them very thinly sautéing them. Like their allium cousins, onions and garlic, let leeks sit for at least 5 minutes after cutting and before cooking. Our Tips for Preparing and Cooking and How to Enjoy sections below will give you more details on the best ways to bring leeks into your meal plan. 

How to Buy Leeks

Leeks should be firm and straight with dark green leaves and white necks. Good quality leeks will not be yellowed or wilted, nor have bulbs that have cracks or bruises. Since overly large leeks are generally more fibrous in texture, only purchase those that have a diameter of one and one-half inches or less. Try to purchase leeks that are of similar size so as to ensure more consistent cooking if you are planning on cooking the leeks whole. Remember, leeks are best in the fall to the early part of spring.
We always encourage you to purchase organic or locally grown foods, and leeks are no exception. Ask your grocer for assistance with all of your organic purchases.

Storing Leeks

Wrapping them loosely in a plastic bag and refrigerating them will help them to retain moisture. There is a great controversy over washing your vegetables immediately upon getting them home and storing them. If they are organic, you can store leeks unlashing and uncut until you’re ready to eat prepare them, but use your judgement. If you do choose to wash them right away, be sure to dry them thoroughly before bagging them.  A really great trick is to include a paper towel for absorption. You can buy natural paper towels that are untreated, and the food will not pick up odors and will stay dry longer.

Did You Know?  Whenever food is stored, four basic factors affect its nutrient composition: exposure to air, exposure to light, exposure to heat, and length of time in storage. Vitamin C, vitamin B6, and carotenoids are good examples of nutrients highly susceptible to heat, and for this reason, their loss from food is very likely to be slowed down through refrigeration.
Cooked leeks are highly perishable, even when kept in the refrigerator. They’ll only stay fresh for about two days. Leeks may be frozen after being blanched for two to three minutes, although they will lose some of their desirable taste and texture qualities. Leeks will keep in the freezer for about three months!

Tips for Preparing Leeks

Cut off green tops of leeks and remove outer tough leaves. Cut off root and cut leeks in half lengthwise. Fan out the leeks and rinse well under running water, leaving them intact. Cut leeks into 2-inch lengths. Holding the leek sections cut side up, cut lengthwise so that you end up with thin strips, slicing until you reach the green portion. Make sure slices are cut very thin to shorten cooking time. Let leeks sit for at least 5 minutes before cooking.

Leeks Juiced!

If you want a powerful infusion of nutrition, juice up some leeks! Throw them into a combo juice other vegetables. Make yourself a fab healthy Bloody Mary minus the alcohol. Add tomatoes, garlic, scallions, a couple carrots and of course the leeks. You will be buzzing around with energy!

The Nutrient-Rich Way of Cooking Leeks

A healthy sauté is the best method for cooking leeks, especially if you want flavor. Throw in a splash of olive oil, a little fresh water and seasonings. Yum!  You can also steam or boil the leeks, but they will be more plain.  If you wish to throw them into a wonderful soup, that is another great cooking solution. 

So don’t hesitate! Go buy some leeks and give it a whirl! We think you’ll be very glad you did 🙂