Oct. 15, 2003 Drinking coffee may help prevent colon cancer, according to a group of researchers in Germany. They identified a potent antioxidant compound in the popular brew that appears in animal studies to boost the activity of phase II enzymes, which are thought to protect against colon cancer, the second leading cause of cancer death in the United States.
The study is scheduled to appear in the Nov. 5 issue of the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society.
Although researchers have suspected for years that coffee consumption may offer some protection against cancer as a result of the drink's high antioxidant content, this study represents the first time that a specific, highly active anticancer compound has been identified in the beverage, say study leaders Thomas Hofmann, Ph.D., professor and head of the Institute for Food Chemistry at the University of Mnster in Germany, and Veronika Somoza, Ph.D., deputy director of the German Research Center for Food Chemistry in Garching.
"Until human studies are done, no one knows exactly how much coffee is needed to have a protective effect against colon cancer," says Hofmann. "However, our studies suggest that drinking coffee may offer some protection, especially if it's strong." For example, expresso-type coffee contains about two to three times more of the anticancer compound than a medium roasted coffee beverage, he says.
The anticancer compound, called methylpyridinium, is found almost exclusively in coffee and coffee products but is not found in significant amounts in other foods and beverages, Hofmann says. Its anticancer activity was unknown until now, he adds.
Methylpyridinium is not present in raw coffee beans but is formed during the roasting process from its chemical precursor, trigonellin, which is common in raw coffee beans. It is present in both caffeinated and decaffeinated coffee, and even in instant coffee, says Hofmann.
To investigate the theory that coffee fights cancer, Hofmann and his associates prepared a conventional coffee beverage using roasted, decaffeinated beans from Columbia. Specially prepared extracts of the brew were then exposed to laboratory preparations of human intestinal cells for three days and results were compared to cells that were not exposed to coffee.
In the cell study, coffee extracts significantly boosted activity levels of phase II enzymes in a dose dependent manner, the researchers say. In other words, the higher the quantity of coffee, the higher the increase in the activity level of the enzymes. Analysis of the extract showed that the most active anticancer compound was methylpyridinium.
To determine whether the compound had a similar effect in living systems, a group of 24 rats was evenly divided into three groups and each group was fed either a standard diet, a diet mixed with coffee extract, or a standard diet containing pure methylpyridinium.
Blood tests showed that rats fed the coffee extract had a 24 to 40 percent increase in phase II enzyme activity compared to control animals. Pure methylpyridinium also significantly boosted the enzymes' activity levels. The results provide strong support for coffee as a cancer fighter in living systems, Hofmann and Somoza say.
The researchers plan to conduct additional tests in the future to determine whether methylpyridinium is an effective cancer fighter in humans and whether it has any side effects.
If you don't like coffee but still want its anticancer benefits, there may be an option in the future: A pill or dietary supplement enriched with methylpyridinium could one day be developed, the researchers predict.
Funding for this study was provided by the German research associations FEI (Research Association of the German Food Industry), AiF (German Federation of Industrial Research Associations) and the Ministry of Economics and Technology.
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