The 10 highest ORAC fruits, in descending order, are prunes, raisins, blueberries, blackberries, strawberries, raspberries, plums, oranges, red grapes and cherries. The 10 highest ORAC vegetables are garlic, kale, spinach, Brussels sprouts, alfalfa sprouts, broccoli florets, beets, red bell peppers, onions and corn. A study of ferrets explains how high-dose beta carotene supplements may have increased lung cancer rates among smokers in two large intervention trials reported in 1994 and 1996. Excess beta carotene stored in the lungs became oxidized into products that turned the normal control of cell division upside down. These oxidized metabolites decreased a tumor suppressor and increased a tumor promoter in the animals' lungs.
Ferrets metabolize beta carotene very much like humans.
Two other groups got either the supplement or smoke exposure, while a control group got neither. The group getting both treatments had the strongest precancerous changes. The products of genes that promote cell division were three- to fourfold higher in these animals than in the control group. The findings point out the importance of understanding how the body handles nutrients before high doses are recommended. Beta carotene in amounts obtained from fruits and vegetables is completely safe.