Antioxidants and polyphenols -- cancer prevention compounds -- are found in highest levels in white tea, which is the least processed of all teas, writes lead author Gayle. A. Orner, PhD, a researcher with the Linus Pauling Institute at Oregon State University.
White tea is relatively rare and is found in specialty tea shops, over the Internet, and in some grocery stores. Green tea, which undergoes some processing, has higher polyphenol levels than black tea, which gets the most processing, Orner says.
Her study of teas' protective effects against colon cancer appears in the February issue of Carcinogenesis.
In a study involving mice, Orner and colleagues tested the benefits of green tea, white tea and a drug called sulindac, which is a nonsteroidal anti-inflammatory (NSAID) that, like high-dose aspirin, has been shown to prevent progression of colon cancer and decrease the death rate.
Orner's study used mice that were genetically predisposed to develop tumors in their intestines.
After 12 weeks of treatment, mice that were given white tea, green tea, or low-dose sulindac had significantly fewer tumors than mice that received no treatment.
Mice that received no treatment developed about 30 tumors. Those that consumed green tea had an average of 17 tumors. Mice given white tea had 13 tumors. Mice given both sulindac and white tea had 80% fewer tumors -- an average of six.
It's evidence that tea's effects on metabolism can potentially block some cancer-causing effects, she explains. In fact, the concentrations of tea the mice got were comparable to those consumed by humans, she says.
"Therefore, this widely consumed beverage may be useful in the prevention of intestinal cancer in genetically predisposed individuals," she writes.
"These are pretty exciting results," Orner says in a news release. "What's especially significant is that as far as we can tell, consumption of tea has none of the side-effects of NSAIDs, which can be severe, including bleeding, ulcers, and even death."
The use of NSAIDS for cancer prevention, heart disease, and other concerns is increasingly common with many people, and high aspirin intake has been associated with a 40% to 50% decrease in death from colon cancer, she notes in her paper.
To get the same colon cancer-prevention benefits of green tea or white tea, drink about three mugs of tea daily, she says. This is based on studies in Japan with green tea and gastric cancer, where researchers essentially concluded "the more, the better."