Tea is a beverage consumed by hundreds of millions of people around the world. The three main types of tea are green, oolong and black. What separates these teas in nutritional quality and quantity is the type of processing each undergoes. Green tea processing avoids fermentation which compromises  nutritional potency. Oolong tea is partially fermented and black tea is completely fermented.

Few other foods or beverages contain as many health benefits as green tea. Green tea is the ideal replacement for coffee because it invigorates and calms the body without drowsiness. It contains about one third the amount of caffeine as coffee and L-theanine which negates the negative side effects of caffeine. Other benefits of L-theanine are reduced stress and anxiety and improved concentration and learning.

Green tea is considered to be a healthier beverage than pure water because it not only hydrates the body as well as water, but it helps protect against many diseases. It is reported to have the highest level of polyphenol antioxidants making it as valuable as vitamin C and E in the fight against health threatening, free radical damage.

Free radicals naturally occur in the body, but exposure to external toxins such as air pollution, cigarette smoke, ultraviolet rays and radiation can cause an overabundance of these particles which can damage cells and DNA.

Green tea also contains vitamin C, tocopherols, carotenoids, minerals such as selenium, zinc, chromium and manganese and several phytochemical compounds.

More than one thousand studies have been conducted regarding the health benefits of green tea. Most of the research is based on the amount consumed in Asian countries which is about three cups daily. The evidence suggests that green tea drinkers have a lower risk of a wide range of illnesses from viral and bacteria infections to diseases such as cancer, heart disease, stroke and osteoporosis.

A recent study suggests that green tea extract increases fat burning. The research shows that after taking the extract and engaging in moderately intense exercise, fat oxidation increased by seventeen percent. Research also showed that a higher percentage of the bodies total daily energy needs came from fat calories.

One particular type of polyphenols found in green tea known as catechins, has been found effective in preventing the absorption of glucose resulting in fat loss. One particular catechin, COMT is effective in enhancing metabolism and fat burning without any rise in heart rate or blood pressure.

Several studies have been conducted showing green teas ability to inhibit certain enzymes that cause arthritic inflammation. It has also been found to have many other anti-inflammatory compounds. It contains fifteen compounds that protect against ulcers. It is believed that long term use can prevent ulcers caused by non-steroidal anti-inflammatory drugs (NSAIDS).

Green tea contains a flavonoid called EGCG which has been found effective at inhibiting cancer tumor growth. Types of cancer it has been found effective against are colon, bladder, pancreatic, lung, small intestine, stomach and breast cancer. One recent study involving several thousand woman consuming green tea daily showed a ninety percent lower occurrence of breast cancer.

Japanese studies have shown that green tea daily intake, decreases the risk of heart disease. The more the tea is consumed, the lower the risk of heart disease. An increase of free radicals in the arteries is a key factor in the development of heart disease. Recent research shows that catechins found in green tea inhibit free radical production in the arteries.

Many other studies show that green tea is effective in lowering blood pressure, LDL cholesterol, triglycerides and preventing blood clots. According to a 2005 study, adding milk to green tea significantly reduces the antioxidant capability of the tea and should be avoided.