Food carotenoids and cancer prevention: An overview of current research

Carotenoids are plant pigments that are present in the human diet as microcomponents of fruit and vegetables. Since 1980, a consistent bulk of the results from both epidemiologic and experimental studies has strongly suggested that beta-carotene, a widespread food carotenoid with provitamin A activity, could prevent the onset of cancers, especially lung cancer. Unfortunately, subsequent large-scale intervention studies failed, with one exception, to demonstrate any chemopreventive potency for beta-carotene supplementation in humans, revealing a lack of knowledge of the mechanisms involved. In addition to their antioxidant properties, which have long been thought to be the clue to their biological effects, carotenoids appear to have a variety of cellular actions that make them remarkable 'physiological modulators'. Research is still needed before new chemoprevention trials can eventually be undertaken on a strong scientific basis.