Lettuce botanically known as Lactuca sativa is a binennial plant from the daisy family Asteraceae. It is most often grown as a leafy vegetable and can be eaten either raw or included in salads, sandwiches, hamburgers, tacos.
Lettuce could also be added to many other dishes or cooked as in Chinese cuisine, which the stem becomes just as important as the leaf. Both the English name and the Latin name of the genus are ultimately derived from lac, the Latin word for “milk”, referring to the plant’s milky juice. Mild in flavor, it has been described over the centuries as a cooling counterbalance to other ingredients in a salad. The lettuce plant has a short stem initially (a rosette growth habit), but when it gradually blooms, the stem and branches lengthen and produce many flower heads that look like those of dandelions, but smaller. This is referred to as bolting. When grown to eat, lettuce is harvested before it bolts. Lettuce is used as a food plant by the larvae of some Lepidoptera.
Lettuce is grown commercially worldwide, requiring light, sandy, humus-rich, moist soil. It is normally grown by early and late sowing in sunny positions, or summer crops in shade. Ideally, lettuce plants require a rich, humous-laden soil that will hold moisture in the summer. They may require the soil to have lime added as a soil pH of 6.5 is just right. Quite often though, lettuce is grown between rows of slower growing plants like brussel sprouts or broccoli etc. This is called a catch crop. Water is a vital ingredient and lettuce prefers the soil to be moist at all times. Lettuce plants do not like hot sunny conditions, preferring a lightly shaded site for summer varieties.
The earliest depictions of lettuce were seen in the carvings of the Senusret I temple at Karnak. Lettuce was considered an aphrodisiac food in Ancient Egypt. Later, Ancient Greek physicians believed lettuce could act as a sleep inducing agent. The Romans cultivated it, and eventually made its way to the Papal Court at Avignon, France. Christopher Columbus introduced lettuce to the New World.
There are six commonly recognized cultivar groups of lettuce that includes the Butterhead (Leaves have a buttery texture), Chinese lettuce (generally have long sword shaped, non head forming leaves bitter and robust flavor. Used in stir-fried dishes and stews), Crisphead also called Iceberg (resembles a cabbage, generally t also called he mildest of the lettuces, valued more for their crunchy texture than flavor), Looseleaf (is tender, delicate and mildly flavored leaves), Romaine also called as Cos (leaves with firm rib down the center and is tolerant to heat unlike other lettuces) and finally the Summer Crisp also called Batavian (forms moderately dense heads with a crunchy texture and are intermediate between iceberg and looseleaf types).
Some lettuces (especially iceberg) have been specifically bred to remove the bitterness from their leaves. These lettuces have high water content and so are less “nutritionally dense” than are the more bitter lettuces and those with darker leaves. While all lettuces contain antioxidants and Vitamin K, romaine and looseleaf lettuce contain five to six times the Vitamin C and five to ten times the Vitamin A of iceberg. Romaine and butterhead lettuce are good sources of folate. Lettuce naturally absorbs and concentrates lithium
Lettuce is a low calorie food and is a source of vitamin A and folic acid. Iceberg lettuce is the most popular lettuce in the United States. It is a head lettuce that is also low in nutritional value and flavor. Because of its superior shipping qualities, iceberg has been most available which accounts for it popularity. The most abundant nutrient in iceberg lettuce is water. Dark green lettuce leaves always indicate higher fiber, flavor and nutritional value.
Lettuce is a cool weather crop. It can be divided into two categories; head lettuce and leaf lettuce. Leaf lettuce and romaine provide flavor and crunch and are excellent for salad and sandwich selections. Lettuce leaves should be free of wilt, rot and rust. Harvest crisp green leaves. Wrap fresh, unwashed leaves in plastic warp and store in the refrigerator. Avoid storing lettuce with apples, pears or bananas. These fruits release ethylene gas, a natural ripening agent that will cause the lettuce to develop brown spots and decay quickly. Toss lettuce that looks slimy or has black spots. The slime is the residue of bacterial decomposition and the black spots are usually mold.
The nutritional value of lettuce varies with the variety. Lettuce in general provides small amounts of dietary fiber, some carbohydrates, a little protein and a trace of fat. Its most important nutrients are vitamin A and potassium. Lettuce, except iceberg, is also a moderately good source of vitamin C, calcium, iron and copper. The spine and ribs provide dietary fiber, while vitamins and minerals are concentrated in the delicate leaf portion. For optimal nutritional value, lettuce should be eaten while it is fresh and crisp.
The mild flavor of fresh lettuce leaves are well complimented by fresh or dry herbs. Lettuce is the base for most of the green salads. The simplest way to appreciate a tossed green salad is with a vinaigrette dressing. Keep it simple. When the dressing becomes too complicated, the mild garden greens can be overpowered.
As lettuce is pretty low in calories, it makes a perfect snack for all those trying to lose weight. Lettuce, being high in dietary fiber, aids digestion and is good for those suffering from constipation. The high magnesium content in lettuce makes it rich in reviving powers, in relation to muscular tissues, brain and the nerves. Those suffering from gastritis, gout, irritable bowel, obesity, sexual addiction, stress, tuberculosis, ulcers and urinary tract diseases might benefit from the regular consumption of lettuce.
The nutritional values per 100 gms of lettuce are:
Carbohydrates: 2.2 g
Dietary Fiber: 1.1 g
Fats: 0.2 g
Protein: 1.4 g
Water: 96 g
Vitamin A: 166 μg
Folate (Vitamin B9): 73 μg
Vitamin C: 4 mg
Vitamin K: 24 μg
Iron: 1.2 mg
Energy: 10 kcal (60 kJ)