Numerous experiments have shown that certain polyphenols, mainly flavonoids, can protect against heart disease and have anticancer, antiviral and antiallergic properties.
In one of the most well known examples, consumption of red wine, which contains the polyphenol resveratrol, has been associated with reduced risk of cardiovascular disease.
But researchers from the Universidade do Porto, Portugal found that such phenolic compounds could also fight breast cancer, the most common cancer among women in the European Union. Approximately one woman in 10 in Europe will develop breast cancer at some point in her life, according to the European Parliament's Directorate-General for Research.
They investigated the effect of epigallocatechin gallate (EGCG), xanthohumol and resveratrol, substances present in significant concentrations in tea, beer and red wine, respectively, on the growth of a human breast cancer cell line, MCF-7.
All three polyphenolic compounds tested showed a significant effect, decreasing breast cancer cells' proliferation, and at concentrations that were not toxic to cells.
Xanthohumol, found in beer, was the most potent polyphenol over breast cancer cell growth: it showed its effect more rapidly and at a lower concentration than the others.
EGCG was the least potent on a weight basis, although that may have no therapeutic meaning since it was also the least toxic compound, meaning it can be given in higher doses, said the researchers.
The results "add support and meaning to epidemiological studies that relate consumption of certain beverages with a lesser incidence and prevalence of cancer," said the researchers.
They warned however that the study does not call for women to increase alcohol consumption as a means of breast cancer prevention. Numerous studies have found that regular intake of alcohol affects the levels of important female hormones, exposing women's breast cells to higher levels of oestrogen when alcohol is consumed. This may in turn trigger the cells to become cancerous.
Further studies will be required before these compounds or the releveant beverages can be recommended to help prevent cancer.
The results will be presented at the American Physiological Society's (APS) annual scientific conference, Experimental Biology 2003, being held 17-21 April at the Washington DC Convention Center.