Delicate flavoured leeks are cylindrical, leafy stalks obtained from the onion-like plant in the Allium family. They are biennial, tall, slender plants with long cylindrical stem composed of overlapping leaves. They are commonly used as vegetables in many parts of Europe, America, and Asia.
Botanically, they belong to the Alliaceae family of bulbous plants, of the genus Allium. However, unlike their fellow allium members such as onion, shallots, garlic…etc, they do not form bulbs.
Scientific name: Allium ampeloprasum var. porrum.
The plant requires well-drained fertile soil to flourish. In general, it is cultivated as annual crop in many parts of Europe and Asia. Planting can be done by either sowing seeds or transplanting seedlings that takes about 100-120 days to harvest.

In general, leeks are planted in deep trenches to deprive sun light exposure which otherwise would turn their stems green (chlorophyll pigmentation) due to photosynthesis. As the plant grow, fill in the trench by pulling surrounding earth to create a mound around the individual plants. This method is applied in order to obtain long blanched stem.

Health benefits

Leeks contain many noteworthy flavonoid anti-oxidants, minerals, and vitamins that have proven health benefits.

Leeks are low in calories. 100 g fresh stalks contain 61 calories. Further, their elongated stalks provide good amounts of soluble and insoluble fibre.

Though leeks contain proportionately less thio-sulfinites than that in garlic, they still possess significant amounts of these anti-oxidants such as diallyl disulfide, diallyl trisulfide and allyl propyl disulfide. These compounds convert to allicin by enzymatic reaction when the stalk disturbed (crushing, cutting etc).

 Laboratory studies show that allicin reduces cholesterol production by inhibiting HMG-CoA reductase enzyme in the liver cells. Further, it also found to have anti-bacterial, anti-viral and anti-fungal activities.

Alicen also decreases blood vessel stiffness by release of nitric oxide (NO); thereby bring reduction in the total blood pressure. It also blocks platelet clot formation and has fibrinolytic action in the blood vessels, which helps decrease overall risk of coronary artery disease (CAD), peripheral vascular diseases (PVD), and stroke.

Leeks are great source of minerals and vitamins that are essential for optimum health. Their leafy stems indeed contain several vital vitamins such as pyridoxine, folic acid, niacin, riboflavin, and thiamin in healthy proportions. 100 g fresh stalks provide 64 µg of folates. Folic acid is essential for DNA synthesis and cell division. Their adequate levels in the diet during pregnancy can help prevent neural tube defects in the new-born babies.

In addition, leeks are one of the good source of vitamin A (1667 IU or 55% of RDA per 100 g) and other flavonoid phenolic anti-oxidants such as carotenes, xanthin, and lutein. They also have some other essential vitamins such as vitamin C, K, and vitamin E. Vitamin C helps body develop resistance against infectious agents and scavenge harmful, pro-inflammatory free radicals.

Further, its stalks have small amounts of minerals such as potassium, iron, calcium, magnesium, manganese, zinc, and selenium.

Cardiovascular Support:  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.

Vision:  Consume leeks as a source of lutein and zeaxanthin. These compounds contribute to healthy eyesight. They protect your eye tissues from oxidative damage -- harmful oxidation of your DNA and cell membranes -- by filtering out harmful light rays as they enter your eye. The American Optometric Association also notes that lutein and zeaxanathin, when consumed in adequate amounts, protect you from cataracts and age-related macular degeneration. The AOA recommends 12 milligrams of lutein and zeaxanthin daily to reap these benefits, and each cup of leaks contains 1.7 milligrams, or 14 percent of this goal.

Anti-cancer properties:  Leeks are a good source of allyl sulphides which have been shown to reduce the risk of developing certain cancers, particularly stomach, prostate, and colon cancer.

Fight infections:  Leeks also act as an antiseptic agent, which help the body fight against infection. You may apply leek extract on a wound to prevent the infection.

Improve digestive health:  Leek is one of the few foods that contain prebiotics, a type of good bacteria, which is necessary for a better nutrient absorption. It eliminates noxious waste matter in the body, stimulates peristaltic action and secretes digestive fluids, thereby improving digestive function.

Maintain healthy cholesterol levels: A regular intake of leeks has been associated with the decrease in bad (LDL) cholesterol and raise in the level of good (HDL) cholesterol.

Good for pregnant women: Leek is very essential for pregnant women as they contain considerable amount of folate. The folate consumption during pregnancy has been shown to reduce the risk of neural tube defects.

Strengthen bones: Leeks are a rich source of calcium and magnesium. The calcium along with magnesium is essential for bone health, helping to convert vitamin D into its active form in the body and thus strengthen the bones.

Prevent Anaemia: Due to its iron content, leeks can also help in preventing various types of anaemia, particularly iron-deficiency anaemia. It is also rich in Vitamin C, which can help in better absorption of iron in the body.