Evidence continues to mount in favour of the consumption of white and green tea with the publication of findings from a new study that suggest these teas provide as much protection against colon tumours as the well recognised, and effective, prescription drug sulindac. But of particular interest - the powerful combination of tea and drugs.
Scientists at the Linus Pauling Institute at Oregon State University (OSU) claim that their findings could influence approaches to cancer prevention or therapy, especially for people who have trouble with the side effects that can be associated with regular use of non-steroidal anti-inflammatory drugs, or NSAIDs, such as sulindac or aspirin.
The study also indicated that routine consumption of green or white teas could be especially effective in combination with NSAIDs, and provide more cancer protection than either of the products separately.
"Tea is one of the most widely consumed beverages in the world, and recent upswings in the sales of green tea in the United States can be attributed to reports of potential health benefits against cancer and other chronic diseases," said Gayle Orner, an OSU research associate. "Teas exert significant protective effects in experimental animal models of skin, lung, oesophageal, gastric, hepatic, small intestinal, pancreatic, colon, bladder and mammary cancer."
OSU's Linus Pauling Institute has been involved in efforts to examine the effectiveness of white versus green tea in blocking mutagens and preventing cancer. In this latest study, they examined green and white teas that have high levels of the protective polyphenols called catechins, and also compared these teas to sulindac. This drug is commonly used around the world for many purposes, including the prevention of certain colon cancers.
"We have evidence that consumption of tea at the same time as a person ingests mutagens can potentially block some of the effects of the mutagens through changes in metabolism," said Rod Dashwood, a professor at the Linus Pauling Institute. "But since everyone probably has some DNA damage in their cells, another question becomes, is there anything we can do to prevent cancer progression even after cells are damaged?"
To study this, the researchers used as a model a special group of laboratory mice that are genetically predisposed to tumour development, especially in their intestines.
A group of these mice that received no treatment each developed about 30 polyps in their colons. Other research has shown that a therapy with sulindac, the prescription NSAID, could cut polyp formation in these mice by about half.
But consumption of green tea, the scientists found, reduced the number of tumours in the mice from an average of 30 to 17; and consumption of white tea from an average of 30 to 13. Mice given both sulindac and white tea, in combination, saw a tumour reduction of about 80 per cent, from 30 tumours to six.
"These are pretty exciting results," said Orner. "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."
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 40-50 per cent decrease in colon cancer mortality, the researchers note in their report.
Although the complications from prolonged use of NSAIDs can be significant, they often are dose-dependent, the researchers add. Any cancer preventive agent that worked effectively in combination with NSAIDs and allowed use of lower dosages could be quite significant, the scientists said, and green or white tea consumption may fit that description exactly.