Researchers from the Lombardi Comprehensive Cancer Center at Georgetown University explain how pentameric procyanidin (pentamer), a natural compound found in cocoa, deactivates a number of proteins that likely work in concert to push a cancer cell to continually divide.
"There are all kinds of chemicals in the food we eat that potentially have effects on cancer cells, and a natural compound in chocolate may be one," said the lead author, Robert B. Dickson, professor of oncology.
Procyanidins, mixtures of oligomers and polymers composed of the antioxidant flavonoids catechin or epicatechin, are found in a range of foods, including nuts, fruits, spices and some vegetables.
Flavonoids found in chocolate include the main flavonoid epicatechin, and catechin, and polymers of these, the proanthocyanidins. These antioxidants may protect cells from the damage caused by unstable molecules known as free radicals, which are thought to contribute to both heart disease and cancer development.
The primary family of flavonoids contributing to the antioxidant benefit in chocolate is the procyanidins, and of the various types of procyanidins, pentamer seem to be strongest, according to a number of studies.
The Georgetown researchers looked at what happened when they used a purified preparation of pentamer on a variety of breast cancer cells, compared to treatment on normal breast cells. They used a variety of tests to find and identify proteins that were deactivated in the cancer cells.
They identified two well-known tumour suppressor genes, as well as two other proteins known to be involved in regulating the "cell cycle" - the progression of a cell from a state of being "quiet" into division and growth.
They specifically found that the breast cancer cells stopped dividing when treated with pentamer and that all four proteins were inactivated. Furthermore, expression of one of the genes was reduced.
Dickson notes that "the novel aspect here is that a pattern of several regulatory proteins are jointly deactivated, probably greatly enhancing the inhibitory effect compared to targeting any one of the proteins singly."
But for the moment, the researchers are unaware as to why pentamer deactivates these proteins simultaneously, stopping the cell cycle. This will be the focus of future research.
Dickson stresses that this research, which is part of a series of studies conducted at Georgetown on the chocolate-cancer connection, does not mean that people who eat chocolate will either reduce their cancer risks or treat a current case.
"Although the study was conducted in breast cancer cell cultures, the finding could potentially apply to other cancers," he says.
Pushing the potential antioxidant activity of chocolate in a range of new formulations may help confectionery makers scoop up additional sales in an stagnant market marked by eroding sales as the increasingly health conscious consumer turns away from chocolate products.
"Western European sales have also been affected by a rising sense of health consciousness, having a particular impact on the chocolate segment," John Band, consumer markets analyst at Datamonitor said recently.
Sales growth for chocolate across Europe is slated to slow down in future years, with value sales likely to reach €5.6 billion by 2007, an increase of just 4 per cent.
Britain is far ahead of its continental rivals when it comes to chocolate consumption, accounting for 32 per cent of the total market by value in 2003 - estimated at €5.3 billion.
But a recent report from Datamonitor shows chocolate consumption is slowing down as health and diet concerns impact sales.
According to the market research firm, the pace of growth in the market is slated to slow down, kicking off in 2004 when overall chocolate volume sales rose by less than 1 per cent to 605m kg.
Full findings for the study are available from the university site.