Drinking coffee may help prevent colon cancer, say German researchers, who have identified a potent antioxidant compound in the popular beverage that increased protection against the disease in animal studies.
Scientists have suspected for years that coffee could offer some protection against cancer thanks to its high antioxidant content, but for the first time they identified a specific, highly active anticancer compound in the drink that boosts the activity of phase II enzymes.
"Until human studies are done, no one knows exactly how much coffee is needed to have a protective effect against colon cancer," said study leader Dr Thomas Hofmann, professor and head of the Institute for Food Chemistry at the University of Mnster in Germany. "However, our studies suggest that drinking coffee may offer some protection, especially if it's strong."
Expresso coffee contains about two to three times more of the anticancer compound than a medium roasted coffee beverage, he said.
The study, scheduled to appear in the November 5 issue of the Journal of Agricultural and Food Chemistry, revealed that coffee contains the anticancer compound methylpyridinium, not found in significant amounts in other foods and beverages. Its anticancer activity was unknown until now, said Hofmann.
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, said Hofmann.
Hofmann and his colleagues prepared a conventional coffee beverage using roasted, decaffeinated beans from Colombia. 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 reported. 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.
The chemical was then tested on a group of 24 rats, evenly divided into three groups. 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 24-40 per cent 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, the researchers claim.
Further research is needed to determine methylpyridinium's effects on humans. The researchers also suggested that a dietary supplement could be developed to offer the benefits of the coffee chemical to those not keen on the beverage.
Other research out this week suggests that coffee could also boost male fertility, according to a Brazilian team presenting evidence at the annual American Society for Reproductive Medicine conference in Texas.
In tests on 750 men awaiting vasectomy operations, coffee drinkers were found to have better sperm motility. The scientists have proposed research on coffee-based treatments for fertility problems.