One of the most important and abundant of the carotenes, a portion of which the liver converts to vitamin A. It should be noted, however, that while excess vitamin A can be toxic to the body, residual beta carotene is quickly eliminated. Scientists now believe that beta carotene is a powerful ANTIOXIDANT with properties that can contribute to reducing cancer and heart disease. It's found in vegetables like carrots, broccoli, squash, spinach and sweet potatoes. Beta carotene's orange-yellow pigment is also used as a coloring in foods like butter and margarine.Carotenoids are the red, orange and yellow plant pigments that give fruits and vegetables their vivid colors. All fruits and vegetables contain varying concentrations of carotenoids, but their colors are often covered up by green chlorophyll contained in the plant. There are more than 600 different naturally-occuring carotenoids. Some of them have been identified as playing a vital role by protecting our cells and tissues from the damaging effects of free radicals and singlet oxygen. Lycopene, the carotenoid that gives tomatoes their red color, is particularly effective at quenching the destructive free radical singlet oxygen.