Lettuce, with the scientific name of var. ramosa Hort., is a annual or biennial herbaceous crops. Its leaf is long and obovate, dense cabbage leaf ball. It is mainly eaten raw in western because it is crisp and refreshing, slightly sweet. In early years of China, it is usually lightly fry which also make it a delicious dish as well. Now it has follow the western trend and usually just make it as salad and eat it raw with other vegetable and fruits like tomato, carrot, apple and others.
Lettuce is native to the Mediterranean coast but It was said to be 1st cultivated in Egypt. It was this introduced to ancient Greeks and Romans and become a very popular vegetable in Europe now. The vegetable was brought into China since many centuries ago. The vegetable is more popular in the southeast coast of China, especially in the outskirts of cities in Guangdong and Guangxi. In recent years, lettuce is even more popular, and becomes part of many dishes from high class restaurants to road side hawkers.
Lettuce is sweet and cool, it contains a unique enzyme that only available in l the stems and leaves. It is slightly bitter but carry the functions of cooling and refreshing, relieving of pain, reducing cholesterol, and has soothing effect on neurasthenia. It also contains an effective components of mannitol, that help in diuretic and promote blood circulation, and help in healing gastric.
Lettuce contains interferon inducer, which can stimulate human normal cells to produce interferon that can help to resist virus, improve the immunity of human body.
Another substance lettuce has is called protocatechuic acid, which has a significant inhibitory effect on cancer cells, especially in the fight against gastric cancer, liver cancer, colorectal cancer and other digestive system cancer, the effect is remarkable.
Lettuce is also high in Vitamin E, Vitamin C, carotene and other essential nutrients that can to protect eyes, maintain normal vision, relieve dry eyes and fatigue. It also can help a little bit in whitening the skin.
Lettuce also has high content of dietary fiber, often eat lettuce will help to reduce the excessive fat, so lettuce also has the reputation of weight loss lettuce.
The other nutrient content of lettuce includes the large amounts of beta carotene, antioxidant, vitamin B1, vitamin E, vitamin B6. There are a lot of minerals such as magnesium, phosphorus, calcium and a small amount of iron, copper and zinc. Regular intake of lettuce can help to improve digestion and absorption of protein and fat, improve the blood circulation of the stomach.
As lettuce is often eaten raw, it is often became the cause for the outbreak of bacteria, virus and parasite like Salmonella and E. coli.
China is now the largest lettuce producing country in the world. In 2013, it contributes more than ½ of the world production at 13.5 million tons which is also almost 4 times of United States, which is 2nd place with only 3.6 million tons. Other top producing countries includes India, Spain and Italy.