Like most forms of onion, leeks have been grown since ancient times. They were probably derived from Allium ampeloprasum, which grows in the Near East and in countries of the Mediterranean coast. Its traditional connection with Wales arose because Welshmen were said to have worn leeks in their hats in a battle against the Saxons in 460AD to distinguish them from the enemies.
Although leeks belong to the same family as onions, they do not have a pronounced bulb nor the pungent flavor and smell of the other members. Leeks are used as a vegetable in their own right in a wide range of dishes and soups. They can also be used as a simple accoutrement. A wide range of varieties are available, some are harder and some are ready earlier while others are best left until spring. There is a variety that has been bred specifically for its appearance on the bench.
One leek, which weighs approximately 89 grams, contains just 50 calories. With 0.6 calories per gram, the leek is a very low-energy-dense food, and is a good way to add flavor to foods such as soups, stews, grain dishes and omelets without adding a lot of calories. In general, most people eat about the same weight in food regardless of calories. Low-energy-dense foods have fewer calories per gram and can help you feel full on fewer calories, and assist with weight loss.
Carbohydrates provide most of the calories in the leek, and as a sweet onion, some of the carbohydrates are in the form of sugar. One leek contains 13 grams of carbohydrates, 3 grams of sugar and 2 grams of fiber.
The leek is fat-free and contains a small amount of protein; 1 gram in one leek. While you might think Americans are lacking in protein, most get more than enough in their diet, according to the Centers for Disease Control.
Leeks may be low in calories and protein, but they are an excellent source of vitamins A and C, a good source of iron and even contain a small amount of calcium. Both vitamins A and C also help keep your immune system strong and help you fight off infections.