Green tea has been publicized over the past ten to fifteen years in the western world for having antioxidant properties. All types of tea, however, originating from plant Camellia sinensis have some degree of antioxidants. But, much like vitamins in vegetables before and after cooking, the antioxidants in tea vary with how much the tea is processed.
“Processing” tea leaves from the time they’re picked before being put in a tea bag or loose blend includes wilting, drying, oxidizing, heating, and shaping, and the less tea leaves are processed, the more antioxidants a blend of tea has. For example, white tea, the blend claimed to have the highest level of antioxidants, is not wilted or oxidized, while the two teas with the most “processing,” black and oolong teas, have the least amount – although these two tea blends still contain some level of antioxidants.
The antioxidants found in these teas, particularly green tea are said to reduce heart disease and cancer, help with weight loss, and increase bone density. One such study shows that two cups of green per day reduce ovarian cancer risks by 46 percent, as well prevent blood clotting. However, a Japanese study published in the September 2006 Journal of American Medical Association has results showing that consuming green teas lowers death rates from heart disease.
The study, done by Tohaku University, used 400,000 participants ranging from 40 to 79 years of age and analyzed their death rates from heart disease and cancer over a period of eleven years. This study found that those from the group of participants who drank more than five cups of green tea daily had 26-percent lower heart disease rates than those who didn’t drink as much tea during the first seven years of study.
Aside from reducing heart disease and cancer risks, antioxidants found in teas other than green tea are said to be beneficial, as well. For example, a study published in September 2001 in The Strait Times discusses mice fed oolong teas seemed to age less than those who drank plain water.
Another Japanese study found that antioxidants in green teas can block the biochemical process in producing an allergic response and, from later studies in 1999 and 2002, can be beneficial in controlling arthritis inflammation. Antioxidants in green and other similar teas have also been shown to lower bad cholesterol levels by ten percent with five cups are drank per day.
One of the more defining studies, however, was one published in U.S. News and World Report in May 2002. The study examines people who drink caffeinated teas from Camellia sinensis plants, including white, green, black, and oolong teas, and those who drank larger quantities of these teas regularly were found to have higher bone mineral densities than those who didn’t.
Green tea, recently, has been thought to help with weight loss, but weight loss is correlated mostly by the caffeine in the green tea, rather than antioxidants. But, rather than taking caffeine pills for weight loss, green tea powder and pills have been shown to be more effective.