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White Tea Antioxidants Strong Potential in Fighting Cancer
Adapted from Reuters Health, March 30, 2000
White tea, known to many tea connoisseurs and long a popular drink in China, may have the strongest potential of all teas for fighting cancer, according to Oregon State University researchers. They presented the first research ever on white tea March 29th at a national meeting of the American Chemical Society.
Among the rarest and most expensive varieties of tea, white tea is produced almost exclusively in China. It belongs to the same species (Camellia sinensis) as other tea plants, but has a higher proportion of buds to leaves. The buds are covered by silvery hairs, giving the plant a whitish appearance.
Some teas are processed more than others. White tea is rapidly steamed and dried, leaving the leaves "fresh." Green tea, composed of mainly leaves, is steamed or fired prior to being rolled. Oolong and black teas get their dark color and flavor from additional processing, including fermentation which is thought to reduce some levels of antioxidants that may effect health.
White tea appears to have more potent anticancer qualities than green tea, according to studies performed at the Linus Pauling Institute of Oregon State University in Corvallis. The researchers tested the tea to determine whether it could help prevent genetic mutations in bacteria, and colon and rectal cancer in cancer-prone rats. The rats were offered white tea - at a strength equivalent to steeping a tea bag in a cup for 5 minutes - instead of water for 8 weeks.
In both experiments, white tea was shown to have a strong protective effect, said Dr. Gilberto Santana-Rios, who described his work at the national meeting of the American Chemical Society.
By some measures, white tea offered twice the protection of water alone, and significantly more protection than green tea, he said." I was surprised by the potency. We were not expecting that much of a good result," Santana-Rios told Reuters Health. Although all teas are made from the same type of plant, they differ in which parts of the plant are collected and how they are processed.
Recent research suggests that how a tea is processed may play a part in tea's cancer-fighting potential. The key, researchers think, is a class of chemicals called polyphenols.
"Many of the more potent tea polyphenols known as catechins become oxidized or destroyed as green tea is further processed into oolong and black teas," says Roderick H. Dashwood, Ph.D., a biochemist in the university's Linus Pauling Institute and principal investigator of the study. "Our theory was that white tea might have equivalent or higher levels of these polyphenols than green tea, and thus be more beneficial."
Chemical analysis has confirmed their ideas. White tea contains the same types of polyphenols as green tea, but in different proportions. Those present in greater amounts may be responsible for white tea's enhanced cancer-fighting potential, says Dashwood.
Lab tests on four varieties of white tea showed that it may prevent DNA mutations, the earliest steps leading to cancer. The researchers say that their latest data indicate that white tea may protect against colon cancer in particular.
Santana-Rios suspects that processing destroys certain anticancer substances found naturally in the tea plant. Many of these chemicals have yet to be discovered, but they may include polyphenols, or catechins, which help give tea its bitter taste. White tea also has more caffeine than other teas, and caffeine is known to have anticancer properties, Santana-Rios pointed out
The researchers say more studies are needed to determine whether white tea actually protects people against cancer. "White tea, and tea in general, is a healthy alternative to other popular drinks, such as sodas," says Dashwood. "But to be on the safe side, one should maintain a healthy lifestyle that includes a diet rich in fruits and vegetables, regular exercise, and avoidance of smoking."
Dr. Dashwood is Associate Professor in the Department of Environmental and Molecular Toxicology at Oregon State University. He also is Principal Investigator with the university's Linus Pauling Institute. Dr. Santana-Rios is a post-doctoral Research Associate with the Linus Pauling Institute.