Studies using animal models have shown that green tea can protect against a number of events associated with the development of cancers, and evidence is appearing that black tea may be equally beneficial. In humans the situation is far less clear. Green tea does seem to be associated with a lower risk of lung cancer in Japan, however black tea may not offer the same protection. It has been reported that green tea may be associated with a lower blood cholesterol in humans and may thus lower the risk of heart disease. Studies with cultured human cells and animals suggest that the catechins can increase the removal of cholesterol from the blood by a receptor mediated mechanism.
Some people are very sensitive to caffeine, so prefer decaffeinated teas and coffee.
Some scientists have found that regular tea appears to have better anti-cancer properties than decaffeinated, but others find no differences. Conclusion Research is continuing into the potential health benefits of tea, so at the moment, treat tea drinking as an enjoyable and refreshing beverage, and if it is good for you, then so much the better. Grolliers Multimedia Encyclopedia , 1995. Segal, M. Tea - a story of serendipity. FDA Consumer, March 1996, pp22-26.