Leeks - Did you know?

With their unique combination of flavonoids and sulfur-containing nutrients, the allium vegetables belong in your diet on a regular basis. There's research evidence for including at least one serving of an allium vegetable in your meal plan every day. If you're choosing leeks, make your individual portion 1/2 cup or greater, and try to include at least one cup of chopped leeks in your recipes.

Many people are unfamiliar with how to cook leeks or how to include them in a Healthiest Way of Eating. We recommend cutting them very thinly and preparing them by using our Healthy Sauté method of cooking. 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. 

Leeks, cooked
1.00 cup
(104.00 grams)

Calories: 32
GI: medium

NutrientDRI/DV

 vitamin K29%

 manganese13%

 copper7%

 vitamin B67%

 folate6%

 vitamin C6%

 iron6%

 vitamin A5%

 fiber4%

 magnesium4%

 calcium3%

 vitamin E3%

 omega-3 fats3%

This chart graphically details the %DV that a serving of Leeks provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Leeks can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Leeks, featuring information over 80 nutrients, can be found under the Food Rating System Chart.

• Health Benefits
• Description
• History
• How to Select and Store
• Tips for Preparing and Cooking
• How to Enjoy
• Nutritional Profile
• References

Health Benefits

Leeks, like garlic and onions, belong to a vegetable family called the Allium vegetables. Since leeks are related to garlic and onions, they contain many of the same beneficial compounds found in these well-researched, health-promoting vegetables.

Cardiovascular Support Provided by Leeks

Leeks contain important amounts of the flavonoid kaempferol, which has repeatedly been shown to help protect our blood vessel linings from damage, including damage by overly reactive oxygen molecules. 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, including their notable amounts of kaempferol, 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. It's important to remember that even in the absence of research studies to confirm health benefits, leeks still belong to the same allium vegetable family as onions and garlic and contain many health-supportive substances that are similar to (or identical with) the substances in their fellow allium vegetables.

Description

Leeks, known scientifically as Allium porrum, are related to garlic, onions, shallots, and scallions. Leeks look like large scallions, having a very small bulb and a long white cylindrical stalk of superimposed layers that flows 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 throughout the year 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 their lower leaf and bulb portion. The flavonol kaempferol is one of leeks' premiere flavonoids, and it's also most concentrated in the lower leaf and bulb. Leeks rank 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.

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.

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 this 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.

How to Select and Store

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. Leeks are available throughout the year, although they are in greater supply from the fall through the early part of spring.

At WHFoods, we encourage the purchase of certified organically grown foods, and leeks are no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including leeks. In many cases, you may be able to find a local organic grower who sells leeks but has not applied for formal organic certification either through the U.S. Department of Agriculture (USDA) or through a state agency. (Examples of states offering state-certified organic foods include California, New York, Oregon, Vermont, and Washington.) However, if you are shopping in a large supermarket, your most reliable source of organically grown collard leeks is very likely to be leeks that display the USDA organic logo.

Fresh leeks should be stored unwashed and untrimmed in the refrigerator, where they will keep fresh for between one and two weeks. Wrapping them loosely in a plastic bag will help them to retain moisture.

Here is some background on why we recommend refrigerating leeks. 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, and even when kept in the refrigerator, will 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 and Cooking

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, known as the chiffonade cut, 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.

The Nutrient-Rich Way of Cooking Leeks

Healthy Sauté is our favorite method for cooking leeks.

Healthy Sauté—similar to Quick Boiling and Quick Steaming, our other recommended cooking methods—follows three basic cooking guidelines that are generally associated in food science research with improved nutrient retention. These three guidelines are: (1) minimal necessary heat exposure; (2) minimal necessary cooking duration; (3) minimal necessary food surface contact with cooking liquid.

Heat 3 tablespoons of broth in 10-12 inch stainless steel skillet until it begins to steam. Add 1 pound of cut leeks. Cover and Healthy Sauté for 4 minutes. Add 2 more tablespoons of broth, reduce heat to medium low, and Healthy Sauté for 3 more minutes uncovered while stirring frequently. Toss with 2 tablespoons of extra virgin olive oil, 1 teaspoon of lemon juice and salt and pepper to taste.

How to Enjoy

A Few Quick Serving Ideas

• Healthy sauté leeks and fennel. Garnish with fresh lemon juice and thyme.
• Add finely chopped leeks to salads.
• Make vichyssoise, a cold soup made from puréed cooked leeks and potatoes.
• Add leeks to broth and stews for extra flavoring.
• Braised leeks sprinkled with fennel or mustard seeds make a wonderful side dish for fish, poultry or steak.
• Add sliced leeks to your favorite omelet or frittata recipe.

Nutritional Profile

Although less well-researched than their fellow allium vegetables (especially garlic and onions), leeks nevertheless contain many sulfur compounds that are either similar to, or identical with, sulfur compounds in these better-researched vegetables. They also contain an impressive amount of polyphenols, including the flavonoid kaempferol. In and of itself, the considerable amount of sulfur found in leeks may play an important role in support of our body's antioxidant and detox systems as well as the formation of our connective tissue. Leeks are an excellent source of vitamin K. They are very good source of manganese, vitamin B6, copper, iron, folate and vitamin C. Leeks are also a good source of vitamin A (in the form of carotenoids, dietary fiber, magnesium, vitamin E, calcium and omega-3 fatty acids. The folate found in leeks is partly present in the bioactive form of 5-methyltetrahydrofolate (5-MTHF).

Introduction to Food Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

Leeks, cooked 1.00 cup 104.00 grams Calories: 32 GI: medium
Nutrient	Amount	DRI/DV (%)	Nutrient Density	World's Healthiest Foods Rating
vitamin K	26.42 mcg	29	16.4	excellent
manganese	0.26 mg	13	7.3	very good
vitamin B6	0.12 mg	7	3.9	very good
copper	0.06 mg	7	3.7	very good
iron	1.14 mg	6	3.5	very good
folate	24.96 mcg	6	3.5	very good
vitamin C	4.37 mg	6	3.3	good
vitamin A	42.22 mcg RAE	5	2.6	good
fiber	1.04 g	4	2.3	good
magnesium	14.56 mg	4	2.0	good
vitamin E	0.52 mg (ATE)	3	1.9	good
calcium	31.20 mg	3	1.7	good
omega-3 fats	0.07 g	3	1.6	good

World's Healthiest Foods Rating	Rule
excellent	DRI/DV>=75% OR Density>=7.6 AND DRI/DV>=10%
very good	DRI/DV>=50% OR Density>=3.4 AND DRI/DV>=5%
good	DRI/DV>=25% OR Density>=1.5 AND DRI/DV>=2.5%

In-Depth Nutritional Profile

In addition to the nutrients highlighted in our ratings chart, here is an in-depth nutritional profile for Leeks. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.

Leeks, cooked (Note: "--" indicates data unavailable)
1.00 cup (104.00 g)	GI: medium
BASIC MACRONUTRIENTS AND CALORIES
nutrient	amount	DRI/DV (%)
Protein	0.84 g	2
Carbohydrates	7.92 g	4
Fat - total	0.21 g	--
Dietary Fiber	1.04 g	4
Calories	32.24	2
MACRONUTRIENT AND CALORIE DETAIL
nutrient	amount	DRI/DV (%)
Carbohydrate:
Starch	-- g
Total Sugars	2.19 g
Monosaccharides	-- g
Fructose	-- g
Glucose	-- g
Galactose	-- g
Disaccharides	-- g
Lactose	-- g
Maltose	-- g
Sucrose	-- g
Soluble Fiber	0.47 g
Insoluble Fiber	0.57 g
Other Carbohydrates	4.69 g
Fat:
Monounsaturated Fat	0.00 g
Polyunsaturated Fat	0.12 g
Saturated Fat	0.03 g
Trans Fat	0.00 g
Calories from Fat	1.87
Calories from Saturated Fat	0.25
Calories from Trans Fat	0.00
Cholesterol	0.00 mg
Water	94.43 g
MICRONUTRIENTS
nutrient	amount	DRI/DV (%)
Vitamins
Water-Soluble Vitamins
B-Complex Vitamins
Vitamin B1	0.03 mg	3
Vitamin B2	0.02 mg	2
Vitamin B3	0.21 mg	1
Vitamin B3 (Niacin Equivalents)	0.31 mg
Vitamin B6	0.12 mg	7
Vitamin B12	0.00 mcg	0
Biotin	-- mcg	--
Choline	-- mg	--
Folate	24.96 mcg	6
Folate (DFE)	24.96 mcg
Folate (food)	24.96 mcg
Pantothenic Acid	0.07 mg	1
Vitamin C	4.37 mg	6
Fat-Soluble Vitamins
Vitamin A (Retinoids and Carotenoids)
Vitamin A International Units (IU)	844.48 IU
Vitamin A mcg Retinol Activity Equivalents (RAE)	42.22 mcg (RAE)	5
Vitamin A mcg Retinol Equivalents (RE)	84.45 mcg (RE)
Retinol mcg Retinol Equivalents (RE)	0.00 mcg (RE)
Carotenoid mcg Retinol Equivalents (RE)	84.45 mcg (RE)
Alpha-Carotene	0.00 mcg
Beta-Carotene	506.48 mcg
Beta-Carotene Equivalents	506.48 mcg
Cryptoxanthin	0.00 mcg
Lutein and Zeaxanthin	962.00 mcg
Lycopene	0.00 mcg
Vitamin D
Vitamin D International Units (IU)	0.00 IU	0
Vitamin D mcg	0.00 mcg
Vitamin E
Vitamin E mg Alpha-Tocopherol Equivalents (ATE)	0.52 mg (ATE)	3
Vitamin E International Units (IU)	0.77 IU
Vitamin E mg	0.52 mg
Vitamin K	26.42 mcg	29
Minerals
nutrient	amount	DRI/DV (%)
Boron	-- mcg
Calcium	31.20 mg	3
Chloride	-- mg
Chromium	-- mcg	--
Copper	0.06 mg	7
Fluoride	-- mg	--
Iodine	-- mcg	--
Iron	1.14 mg	6
Magnesium	14.56 mg	4
Manganese	0.26 mg	13
Molybdenum	-- mcg	--
Phosphorus	17.68 mg	3
Potassium	90.48 mg	3
Selenium	0.52 mcg	1
Sodium	10.40 mg	1
Zinc	0.06 mg	1
INDIVIDUAL FATTY ACIDS
nutrient	amount	DRI/DV (%)
Omega-3 Fatty Acids	0.07 g	3
Omega-6 Fatty Acids	0.05 g
Monounsaturated Fats
14:1 Myristoleic	0.00 g
15:1 Pentadecenoic	0.00 g
16:1 Palmitol	0.00 g
17:1 Heptadecenoic	0.00 g
18:1 Oleic	0.00 g
20:1 Eicosenoic	0.00 g
22:1 Erucic	0.00 g
24:1 Nervonic	0.00 g
Polyunsaturated Fatty Acids
18:2 Linoleic	0.05 g
18:2 Conjugated Linoleic (CLA)	-- g
18:3 Linolenic	0.07 g
18:4 Stearidonic	0.00 g
20:3 Eicosatrienoic	0.00 g
20:4 Arachidonic	0.00 g
20:5 Eicosapentaenoic (EPA)	0.00 g
22:5 Docosapentaenoic (DPA)	0.00 g
22:6 Docosahexaenoic (DHA)	0.00 g
Saturated Fatty Acids
4:0 Butyric	-- g
6:0 Caproic	-- g
8:0 Caprylic	-- g
10:0 Capric	-- g
12:0 Lauric	-- g
14:0 Myristic	-- g
15:0 Pentadecanoic	-- g
16:0 Palmitic	0.03 g
17:0 Margaric	-- g
18:0 Stearic	0.00 g
20:0 Arachidic	-- g
22:0 Behenate	-- g
24:0 Lignoceric	-- g
INDIVIDUAL AMINO ACIDS
nutrient	amount	DRI/DV (%)
Alanine	0.04 g
Arginine	0.04 g
Aspartic Acid	0.08 g
Cysteine	0.01 g
Glutamic Acid	0.13 g
Glycine	0.04 g
Histidine	0.01 g
Isoleucine	0.03 g
Leucine	0.05 g
Lysine	0.04 g
Methionine	0.01 g
Phenylalanine	0.03 g
Proline	0.04 g
Serine	0.05 g
Threonine	0.04 g
Tryptophan	0.01 g
Tyrosine	0.02 g
Valine	0.03 g
OTHER COMPONENTS
nutrient	amount	DRI/DV (%)
Ash	0.59 g
Organic Acids (Total)	-- g
Acetic Acid	-- g
Citric Acid	-- g
Lactic Acid	-- g
Malic Acid	-- g
Taurine	-- g
Sugar Alcohols (Total)	-- g
Glycerol	-- g
Inositol	-- g
Mannitol	-- g
Sorbitol	-- g
Xylitol	-- g
Artificial Sweeteners (Total)	-- mg
Aspartame	-- mg
Saccharin	-- mg
Alcohol	0.00 g
Caffeine	0.00 mg
Note: The nutrient profiles provided in this website are derived from The Food Processor, Version 10.12.0, ESHA Research, Salem, Oregon, USA. Among the 50,000+ food items in the master database and 163 nutritional components per item, specific nutrient values were frequently missing from any particular food item. We chose the designation "--" to represent those nutrients for which no value was included in this version of the database.