Although many tests have been inconclusive and others are still under way, some of the health claims by green tea proponents are:

Longer life

Weight loss

Increased ability to survive after a heart attack

Antioxidants to combat free radicals

Cavity fighting

Higher metabolism, more calories burned

Cancer prevention

Lower cholesterol

Detoxification of blood

Liver function support

Bone density maintenance

Reduced inflammation

Alzheimer's prevention and treatment

Lower risk of diabetes and heart disease

Green tea contains a group of polyphenols known as catechins. The most studied and effective compound is epigallocatechin gallate, better known as EGCG. A growing number of published scientific studies propose that it does protect against cancer and heart disease and aid weight control. It is used as a fat loss aid used in some dietary supplements.

The side effects of green tea are few and mild. They are mainly due to the caffeine content, which the Buddhist monks of the 8th century discovered helped keep them awake during long meditation sessions. Actually, green tea has just enough caffeine to give you a lift, but not enough to cause nervous jitters. It would take four cups to equal the amount of caffeine in just one cup of brewed coffee. There are 8 to 20 mg. of caffeine in green tea, compared to 40 to 60 mg. in black tea and 90 to 150 mg. in coffee. The best known effects of caffeine include increased intellectual activity, improved reading speed, more energy, increased heartbeat, improved alertness, quicker reaction times and a brighter mood. Too much caffeine, on the downside, can cause insomnia, headaches, irritability and muscle tension.

Because of the caffeine content, there are some possible drug interactions. If you are taking any medicines with the ingredients codeine, ephedrine, psedoephrine, theophylline, atropine, aminophylline or warfarin you should consult with your physician and pharmacist before taking green tea products.

Green tea is available in tea bags, loose leaves, and prebrewed in bottles. It is available in caffeinated and decaffeinated varieties. There is also a product called Matcha, which is made of powdered tea leaves that are simply mixed into hot water. If you are not a fan of the flavor, it can also be found in tea blend sodas and fruit juice beverages, tablets, extracts, nutrition bars and liqueur.

Green tea contains zero calories. Just substituting it for higher calorie beverages, particularly soda, will help you reduce your overall calorie intake and help you feel full and more energetic. While nobody knows exactly how much of the active ingredient, EGCG, is necessary, most researchers agree that to reap the benefits, just three to four cups a day are all that are needed.