Tea, which was probably first brewed as a beverage in China around 2700 BCE, is one of the oldest and (after water) the second most consumed drink in the world. Camellia sinensis is an evergreen shrub with shiny, bright green leaves; strongly scented flowers; and brown-green seed-bearing fruit, used to produce tea. It has more than 1500 cultivars, derived mainly from two varieties: C sinensis var. assamica, an Indian, single-stem plant with large, soft, and short-lived leaves, and C sinensis var. sinensis, a Chinese multiple-stem shrub with smaller leaves that are hardier in cooler temperatures. It grows in generally warm and humid climates, preferably in acidic soils, on sloping hills at elevations of up to 2000 meters.
After becoming popular in Europe, tea was spread widely by the forces of colonialism, and large plantations were established in India, Sri Lanka, Africa, and Indonesia. Today, the biggest tea-producing countries are China (1.9 million tons in 2013, or 38% of the world's total), India (1.2 million tons), Kenya (436,000 tons), and Sri Lanka (343,100 tons). Around the world, many cultures celebrate the drink for its contributions to social cohesiveness, flavor, and potential health benefits. And we drink a lot of tea—4.8 million tons worldwide in 2013; China (1.6 million tons), India (1 million tons), and Turkey (228,000 tons) led the way, whereas Americans drank 127,000 tons. The tea industry was worth an estimated $12.5 billion in the United States in 2017.
What's Your Cup of Tea?
Six types of tea come from the C sinensis plant: white, green, yellow, black, oolong, and pu'erh (Table).
||Leaf buds are picked before opening and dried at low temperatures. Least processed of all teas. Most delicate flavors, with highest quantity of antioxidants.||
||Steamed or heated immediately after plucking to stop leaf oxidation and browning. More intense flavors than white, but milder than black; many vegetal flavors.||
||A rare variety; dried longer than green tea. Leaves turn yellow and have a grassy flavor. Made in small quantities, making yellow teas expensive and hard to find.||
||Oxidized longer for stronger flavor. Processing of leaves lowers flavonoid content. Scented varieties are made with added flavors.||
||Partially oxidized; somewhere between a green and black tea. The amount of oxidation determines the flavor.||
||A strong, earthy tea that is fermented (unlike other teas) to mature after oxidation; compressed into bricks or cakes and buried or shelved for many years before drinking.||
From industrial to artisanal, the production and consumption of tea vary tremendously in scale and execution. According to the International Specialty Tea Association, tea quality depends on numerous factors, including the cultivar and condition of the shrub, expertise, whether the leaves are broken when picked, style of plucking and leaf conformity, harvest date, quality and type of processing, moisture, and oxidation. These factors—not to mention how the tea is brewed—will affect the taste and quality of the beverage and, quite possibly, its therapeutic qualities.
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Cite this: Drinking Tea: Are the Health Benefits Real? - Medscape - Jan 17, 2019.