Tea Time for Good Health
Since ancient times, tea has been used as both a beverage and medicine by many cultures of the East. After water, it is the second most common drink worldwide. Research suggests that polyphenols in tea, known as catechins, might help protect against cancer and heart disease. Two cups of tea a day appear to be enough to confer heart benefits. Anti-cancer effects may require more. One researcher funded by the American Institute for Cancer Research (AICR) recommends six eight-ounce cups a day.
A true tea originates from the plant Camellia sinensis. Herbal "teas" are more appropriately referred to as infusions. Red or rooibos "tea" isn't technically a tea, either. It comes from the dried needles of the African rooibos herb.
Due to harvesting and processing differences, tea is split into four main kinds.
Black tea comes from withered leaves that are allowed to fully absorb oxygen from the air, turning dark brown and black. This full oxidation process alters the chemical composition of the leaves, transforming certain phytochemicals. Black tea also has more caffeine than other teas.
Oolong tea is also made from withered leaves, but these are only partially oxidized. The flavor and caffeine content lie between black tea and green tea.
Steaming fresh leaves at high temperatures, then drying and rolling them, produces green tea. The short oxidation process preserves a phytochemical content similar to that of fresh leaves.
White tea is the newest tea on grocery shelves and still a rarity. For this tea, young buds and leaves are rapidly steamed and dried without oxidation. More polyphenols remain because of the minimal processing. White tea has less caffeine than black and green teas.
Which Tea Is Best?
Most of the cancer prevention research done to date concerns green tea. Although all tea leaves contain catechins, the major one being epigallocatechin-3-gallate (EGCG), the EGCG content of green tea leaves is exceptionally high. An eight-ounce cup of green tea can contain up to 300 mg. Because oxidation reduces the amount of active EGCG, black tea has just 40 percent of the EGCG in green tea. No matter how you prepare green tea - with loose or bagged tea, short or long steeping times, hot or boiling water - the amount of EGCG in your cup will have anti-cancer potency because there is so much EGCG in the leaves.
A few studies suggest that white tea may be just as potent as green tea. Some experts also guess that black tea, as well as oolong tea, could contain other antioxidants that compare to EGCG. In fact, more study of the different kinds of teas seems likely to show that any kind of freshly brewed tea can benefit your health.
The American Institute for Cancer Research (AICR) is the only major cancer charity focusing exclusively on the link between diet, nutrition and cancer. The Institute provides a wide range of consumer education programs that help millions of Americans learn to make changes for lower cancer risk. AICR also supports innovative research in cancer prevention and treatment at universities, hospitals, and research centers across the U.S. The Institute has provided more than $70 million in funding for research in diet, nutrition and cancer. AIRC is a member of the World Cancer Research Fund International.
