A team of researchers, from the University of Newcastle upon Tyne in England and Denmark, found the natural pesticide falcarinol in carrots reduced the risk of cancer developing in rats by one third.
In nature, falcarinol protects the roots of carrots from fungal disease. The scientists investigated the compound after a previous published study suggested it could prevent the development of cancer. The researchers carried out the test on 24 rats with pre-cancerous tumors by dividing them into three groups. What was found after 18 weeks is that the rats who ate carrots, along with their ordinary feed and the group which consumed falcarinol with their feed in the quantity equal to that contained in the carrot group were one third less likely to develop full-scale tumors than the rats in the control group.
Dr Kirsten Brandt, a senior lecturer with Newcastle University's School of Agriculture, Food and Rural Development, carried out the research with the University of Southern Denmark and the Danish Institute of Agricultural Sciences. She said: "We already know that carrots are good for us and can reduce the risk of cancer but until now we have not known which element of the vegetable has these special properties.
"Our research allows us to make a more qualitative assessment of the vegetables we are eating, rather than quantitative. We now need to take it a step further by finding out how much falcarinol is needed to prevent the development of cancer and if certain types of carrot are better than others, as there are many varieties in existence, of different shapes, colours and sizes.
"We could also expand our research to include other vegetables. For consumers, it may soon no longer be a case of advising them to eat five portions of fruit and vegetables per day but to eat particular types of these in certain quantities. The research could also lead to more tailored advice for growers regarding the methods they should use when growing vegetables."
The experiment was conducted using raw carrots so researchers do not yet know if eating boiled carrots or drinking carrot juice, for example, would have the same effect.
Dr Brandt, who says she eats "more carrots than most" and grows her own organic varieties, recommended that consumers should eat one small carrot every day, together with other vegetables and fruits, to benefit from their health-giving properties.
Falcarinol is toxic in large amounts but to obtain a lethal dose you would have to eat 400 kilograms of carrots at once. Researchers suspect it is effective because it stimulates mechanisms in the body that fight cancer, although they have yet to carry out a detailed analysis in this respect.
Journal ref. Inhibitory effects of feeding with carrots or falcarinol on development of azoxymethane-induced colon preneoplastic lesions in rats, Kobaek-Larsen et al, Journal of Agricultural and Food Chemistry, 2005
Adapted from materials provided by University Of Newcastle Upon Tyne