绿色,黑色,或乌龙茶——人们喜欢茶。茶的sumption in the world is second only to water, according to Tea USA, a website managed by The Tea Association of the USA Inc., The Tea Council of the USA and the Specialty Tea Institute (STI). While tea has long been believed to have health benefits, it has only been in the past few decades that research has begun to confirm the folklore.

About Tea

茶is a complex beverage which contains a variety of compounds and substances. Among these are flavonoids, polyphenols, tannins, theobromine, amino acids and caffeine. There are differences between the various types of teas — for example, green tea, which is the least processed, has higher levels of antioxidant polyphenols, in particular a substance called epigallocatechin-3-gallate (EGCG), which is believed to be responsible for most of green tea’s health benefits. Black tea, however, the most highly processed, contains fewer polyphenols but two to three times the caffeine. In general, tea contains about half as much caffeine as coffee.

Caffeine in Tea

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Caffeine in tea does seem to have some health benefits. Researchers noted in the 2009 issue of “Archives of Internal Medicine” that high intakes of caffeinated tea and coffee were associated with a reduced risk of diabetes. A Japanese study led by K. Tanaka reported in the April 2011 issue of “Parkinsonism and Related Disorders” that drinking black tea decreased the risk of Parkinson’s disease. In this case the results seemed to be tied to the caffeine, as caffeinated coffee had a similar effect.

Caffeinated Vs. Decaf

茶USA completed an extensive review of research related to tea and health; they found benefits ranging from improved cardiovascular health to a decrease in the risk of some types of cancer. Tea may also help prevent the formation of dental plaque, boost the immune system, decrease the risk of osteoporosis and kidney stones and help with weight loss. Little of this research differentiates between caffeinated and decaffeinated tea, although they note one study found that smokers who drank four cups of decaffeinated green tea per day had a decrease in a biological marker implicated in the development of various forms of cancer. The comparison beverage in this study, however, was water rather than caffeinated tea.

Considerations and Warnings

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If you chose to drink tea for its possible health benefits, the University of Maryland recommends caffeine-free products. So if you are caffeine-sensitive, you may want to reach for the decaf version of your favorite tea. And tea may interact with some prescription medications, so if you regularly drink a lot of tea, you should discuss the implications of medication interactions with a health care professional.