Green tea is made from the leaves from Camellia sinensis that have undergone minimal oxidation during processing.
Green tea originated in China,but it has become associated with many cultures throughout Asia. Green tea has recently become more widespread in the West, where black tea has been the traditionally consumed tea. Green tea has become the raw material for extracts used in various beverages, health foods, dietary supplements, and cosmetic items.
Many varieties of green tea have been created in the countries where it is grown. These varieties can differ substantially due to variable growing conditions, horticulture, production processing, and harvesting time.
Tea consumption has its legendary origins in China of more than 4,000 years ago.
Green tea was first brewed in 2737 BC during the reign of Emperor Chen Nung (or Shennong, in pinyin transliteration).
Green tea has been used as both a beverage and a medicine in most of Asia, including China, Japan, Korea, Thailand, and Vietnam, to help everything from controlling bleeding and helping heal wounds to regulating body temperature, blood sugar and promoting digestion.
Green tea contains a variety of enzymes, amino acids, carbohydrates, lipids, sterols, polyphenols, carotenoids, tocopherols, vitamins, caffeine and related compounds, phytochemicals, and dietary minerals. Numerous claims have been made for the health benefits of green tea based on chemical composition, in vitro and animal studies, though results in humans have been inconsistent and few clear benefits for humans have been demonstrated.
There is also evidence suggesting consuming large volumes of green tea, and in particularly green tea extracts, may cause oxidative stress and liver toxicity.