2008-07-03 10:53:32
Wed Jul 2, 2:45 PM ET
A scientific study published here Wednesday sheds light on why men who eat a lot of broccoli are less likely to develop prostate cancer.
Scientists have already observed that diets rich in cruciferous vegetables -- including broccoli, cauliflower, cabbage, Brussels sprouts, bok choy and kale -- may reduce the risk of prostate cancer and other chronic disease.
But the new research, by scientists at Britain's Institute of Food Research, is the first attempt to show how that works in a clinical study involving people, as opposed to animals or cell models.
For the new study, men at risk of developing prostate cancer ate 400 grams of broccoli or 400 grams of peas a week for 12 months, in addition to their normal diet.
The researchers took samples of prostate gland tissue from the men at the start of the study, at six months and at 12 months, to monitor changes in genes linked to cancer.
"There were more changes in gene expression in men who were on the broccoli-rich diet than on the pea diet, and these changes may be associated with the reduction in the risk of developing cancer," said a statement by the Public Library of Science, which published the work Wednesday in its online journal PLoS ONE.
"The results of the study suggested that relatively low amounts of cruciferous vegetables in the diet -- a few portions per week -- can have large effects on gene expression by changing cell signalling pathways," the statement said.
The signalling pathways are the routes by which information is transmitted to the nucleus of the cell where gene expression occurs.
"Other fruits and vegetables have been shown to also reduce the risk of prostate cancer and are likely to act through other mechanisms," said lead researcher Richard Mithen.
"Once we understand these, we can provide much better dietary advice in which specific combinations of fruit and vegetable are likely to be particularly beneficial.
"Until then, eating two or three portions of cruciferous vegetable per week ... should be encouraged."
Prostate cancer is the most common form of non-skin cancer affecting men in western countries.