Green tea is made from the common tea leaf known as Camellia sinensis which is also used to make black tea. Camellia sinensis has been in use since 500,000 years. It is mainly cultivated in China and India. It was traditionally taken as a refreshing drink and has been consumed in China, India, Japan and Thailand.

It is different from black tea because it isn't processed at all and the oxidation of the green tea is minimal. The leaf from the plant is picked and steamed or pan- dried immediately so that it can prevent oxidation or bacterial growth. The excess water is squeezed out by rolling with hand. In this way the flavor gets released. After that it is fired in driers and packed. Since the tea leaf is not allowed to oxidize the natural ingredients in the leaf are preserved. So it is much more beneficial than other teas. When it is brewed it turns the color into light green and so it is known as green tea.

Scientists are discovering more and more health benefits of green tea. Like most leaves the main content of the tea leaf is water. Fresh leaves have about 80% of water and the rest of the components are catechin, caffeine and Theanine and aminoacids. Catechin is a water soluble polyphenol, It has six primary catechin compounds. catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). Apigallocatechin gallate (EGCG), an antioxidant found in the tea helps in protecting cells and DNA from damage. It is the most active component in green tea. It is helpful in controlling cancer cells, reducing the possibility of heart attacks and atherosclerosis. . It is also used as a weight loss product and enhances immune system. It also protects against Inflammatory Bowel Disease, Diabetes, Liver disease etc. While green tea contains 30% to 40% polyphenols , black tea only contains only 3% to 10% polyphenols. There are different varieties of green tea depending on the area and the method of cultivation of the tea.

It are brewed using water that is under the boiling point (about 80 - 90 ?C), If the water is too hot the tea will turn bitter.

Does green tea have caffeine?

Like all teas Green tea also contains caffeine. An average cup (6 oz) of it contains approximately 30 milligrams of caffeine. Caffeine is a central nervous stimulant. Decaffeinated is also available, even though decaffeination doesn't result in the 100% removal of caffeine.

Possible interactions with medicines are Adenosine , beta-lactam antibiotics, benzodiazepines, propranolol and metoprolol, blood thinning Medications like warfarin, chemotherapy medications, specifically doxorubicin and tamoxifen, anti-psychotic effects of the medication clozapine, ephedrine, Monoamine oxidase inhibitors (MAOIs. Oral contraceptives can prolong the amount of time caffeine stays in the body and may increase its stimulating effects, .With regard to Phenylpropanolamine it, reduces blood levels of lithium. Caffeine and cold medications or weight loss medications taken at the same time can cause increase in blood pressure and may also cause mania.

Now there are green tea pills and green tea extracts are available which are claiming to be helpful in weight loss. Some people do not like the taste of green tea and so these pills and extract comes in handy.