Increasing intake of polyphenols, by eating more fruits and vegetables such as apricots or onions, or taking supplements, may help to prevent intestinal cancer, reports a European research group.
The team found that a complex wine polyphenol mixture could prevent the development of intestinal tumours, although in a second study black tea appeared to have no effects on development of colorectal cancer.
The tests are part of the ongoing Polybind project, designed to improve understanding of the uptake and metabolism of polyphenols, such as quercetin found in onions, and catechins, found in cherries, tea and apricots.
Colon cancer is a major cause of premature death in Europe, accounting for approximately 75000 deaths each year. Polyphenols have previously been shown to have anti-cancer properties.
The researchers assessed the impact of black tea on the metabolism of cooked meat mutagens implicated in colorectal cancer development in humans. A previous study has found that a combination of white and green tea, known for its powerful polyphenol ECEG, could offer as much protection against colon tumours as a prescription drug.
In the current study however the researchers were unable to confirm earlier findings that black tea exerts a statistically significant blocking effect against colorectal cancer development in humans, although it was recognised that the study only investigated short term consumption of tea. Longer term intake of black tea needs to be investigated further, they said.
In a second model, researchers assessed the effects of a complex wine polyphenol mixture on pre-cancerous lesions and tumours of the rat colon. They reported that the red wine polyphenols had a protective suppressing effect against colon carcinogenesis when the exposure to intestinal carcinogens induces a moderate response in terms of tumours developing. Such an effect was not seen when a large number of tumours were induced by chemicals.
The trials are currently pending publication. For more information, contact project co-ordinator, Christine Hill.