Carrots

Beta-carotene has been associated with an increased risk for lung cancer in smokers. The three studies that indicated this association did, however, test the association with amounts of beta-carotene that dramatically exceeded the recommended doses.

Normal, dietary beta-carotene intake should be safe (and, in moderate amounts, may protect against cancer). Excessive beta-carotene supplementation could, however, create a problem.

A balanced diet, that includes one portion of carrots (1/2 a cup of grated carrots) per day, should be fine.

The good news is that cooking doesn't seem to diminish this vegetable's benefits: beta-carotene is not destroyed by the cooking process.

Interestingly, the anti-cancer properties of carrots are enhanced 25% if they are cooked whole rather than chopped up beforehand.

And, for the record, fresh carrots are healthier than carrot juice.

Carrots are low in calories and can therefore be eaten freely. Even just one carrot a day will increase the beta-carotene levels in the body.