According to the Newcastle University study, which will be presented at NutrEvent, a conference on nutrition and health, to be held in France, anti-cancer properties of carrots are more potent if the vegetable is not cut up before cooking.
The study's researchers found "boiled before cut" carrots contained 25 percent more of the anti-cancer compound falcarinol than those chopped up first, reports The BBC.
Experiments on rats fed falcarinol have shown they develop fewer tumours.
Lead researcher Dr Kirsten Brandt, from Newcastle University's School of Agriculture, Food and Rural Development, said: "Chopping up your carrots increases the surface area so more of the nutrients leach out into the water while they are cooked.
"By keeping them whole and chopping them up afterwards you are locking in nutrients and the taste, so the carrot is better for you all round."