Carotenes are naturally occurring compounds that give many vegetables and fruits their color. Beta-carotene is the best known and a precursor of vitamin A. Other carotenes include alpha and gamma-carotene, lycopene, lutein, zeaxanthin, and astaxanthin. Some carotenes act as antioxidants and many are being linked to protection from cancer. Eat generous amounts of colorful vegetables and fruit, as well as a supplement of mixed carotenes. If you take a supplement that contains carotenes, make sure it has 15,000 IU of mixed carotenes.