The genes involved in the growth of prostate cancer tumours may be hindered by eating broccoli, experts claim.
Scientists made the discovery after adding either peas or broccoli to the normal diets of two groups of men for a year.
During the study tissue samples were removed from the men's prostate glands and analysed using "gene chip" technology to gauge the activity of thousands of genes.
The results showed that a broccoli-rich diet produced changes in gene activity, or expression, that were likely to prevent or hinder cancer growth and inflammation in the prostate.
In particular, biological signalling pathways involving two growth factors, TGF beta 1 and EGF, as well as the hormone insulin, were altered.
Growth factors are proteins that typically stimulate cell division or development, and often play a role in cancer.
TGF beta 1, EGF and insulin signalling have all been implicated in prostate and other cancers.
Professor Richard Mithen, from the Institute of Food Research in Norwich, who led the British and Italian team, said: "This is the first study providing experimental evidence obtained in humans that diets rich in cruciferous vegetables may reduce the risk of prostate cancer."
Cruciferous vegetables are a family that includes broccoli, Brussels sprouts, cabbage, cauliflower and kale.