"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.

A team of researchers from the University of Newcastle upon Tyne in England and Denmark found the compound reduced the risk of cancer developing in rats by one third.

Although experts have recommended that people eat carrots for their anti-cancer properties, it has not been known, before now, exactly what component of the vegetable has this effect.

Falcarinol protects carrots from fungal diseases, such as licorice rot that causes black spots on the roots during storage. The scientists investigated the compound after a previous published study suggested it could prevent the development of cancer.

Qualitative Assessment of Vegetables We Eat

The research team carried out tests on 24 rats with pre-cancerous tumors in laboratory conditions. They divided them into three groups and fed them different diets.

The team found that after 18 weeks, rats who ate carrots (the popular orange variety) along with their ordinary feed and the group that consumed falcarinol with their feed -- in an amount equal to that contained in the carrots -- were one third less likely to develop full-scale tumors than the rats in the control group.

"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," says Dr. Kirsten Brandt, a senior lecturer with Newcastle University's School of Agriculture, Food and Rural Development, who carried out the research with the University of Southern Denmark and the Danish Institute of Agricultural Sciences.

"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, colors and sizes," Dr. Brandt points out.

A Carrot a Day

"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," Dr. Brandt suggests.

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.