Green tea is rich in catechin polyphenols, such as epigallocatechin gallate (EGCG). EGCG is an antioxidant with cancer fighting powers.
Studies have shown it can aid in protection against various forms of cancer including esophageal, gastric, skin, ovarian, lung, and colon cancer. Studies have also shown that drinking 2-3 cups per day can lower blood pressure, cholesterol, and decrease the risk of heart attack.
Not only does green tea contain immune boosting antioxidants, but it can also protect your teeth. Tea has bacteria killing properties to fight plaque, gum disease, and bad breath. Tea contains fluoride, which can protect against cavities.
Green tea has gotten a couple of knocks for it's fluoride content, despite the positive attributes, since too much fluoride can be bad for you. It is recommended that a person receive no more than 10/mg of fluoride per day. Loose leaf green tea only contains about 0.3 mg of fluoride, so unless you're drinking about 30 cups per day, don't worry.
Studies suggest that the polyphenols in green tea can help reduce and prevent rheumatoid arthritis. One study found that regular tea drinkers reported to have stronger bones and were less likely to develop arthritis. Those who drank tea regularly for 10 years or more had higher bone mineral density in their spines than non-tea drinkers.