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According to legend, the health effects of tea have been examined ever since the first infusions of ''Camellia sinensis'' about 4700 years ago in China. Emperor Shennong claimed in ''The Divine Farmer's Herb-Root Classic'' that ''Camellia sinensis'' infusions were useful for treating a variety of disease conditions.〔N. H. Woodward, ''Teas of the World'' (1980), as cited in D. A. Balentine, M. E. Harbowy, H. N. Graham, ''Tea: The Plant and Its Manufacture; Chemistry and Consumption of the Beverage'' in ''Caffeine'' ed G. Spiller (1998)〕 Historically as well as today, in regions without access to safe drinking water, the boiling of water to make tea has been effective in reducing waterborne diseases by destroying pathogenic microorganisms. Recently, concerns have been raised about the traditional method of over-boiling tea to produce a decoction, which may increase the amount of pesticides and other harmful contaminants released and consumed. Black tea has been studied extensively for its potential to lower the risk of human diseases, but none of this research is conclusive as of 2015. == Aluminum, iron and other metals == Tea drinking accounts for a high proportion of aluminum in the human diet. The levels are safe, but there has been some concern that aluminum traces may be associated with Alzheimer's disease. A recent study additionally indicated that some teas contained possibly risky amounts of lead (mostly Chinese) and aluminum (Indian/Sri Lanka blends, China). There is still insufficient evidence to draw firm conclusions on this subject. Most studies have found no association between tea intake and iron absorption. However, drinking excessive amounts of black tea may inhibit the absorption of iron, and may harm people with anaemia. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Health effects of tea」の詳細全文を読む スポンサード リンク
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