The leaves and buds of the Camellia sinensis plant used to manufacture green tea have not gone through the same withering and oxidation processes as those used to make oolong teas and black teas. Since its invention in China, the manufacturing and processing of green tea has spread to various East Asian nations.
There are many different kinds of tea, and they vary greatly depending on the type of C. sinensis utilized, the growing environment, the horticulture techniques used, the production process, and the time of harvest.
Green, yellow, or light brown teas are the most common colours for brewed green teas. Steamed green teas have a vegetal, sweet, and seaweed-like flavour profile, while pan-fired green teas often have a grassy, toasted flavour. Most green teas should have a rather light colour and only a slight astringency when properly brewed.
Regular tea contains caffeine and phytochemicals such polyphenols but is 99.9% water, has 1 kcal per 100 mL serving, has no appreciable nutrient content (table), and is 99.9% water.
Although there have been many claims made about the health advantages of this tea, human clinical research has not shown strong support for these claims. At the European Commission’s request, a panel of scientists produced a report on the health effects claims in 2011. In general, they concluded that the claims made for it were not adequately supported by the available scientific data. Although the caffeine in it may help with mental clarity, there is very limited, inconclusive evidence that frequent green tea consumption reduces the risk of cancer or cardiovascular disease.