Anticarcinogenic activities of carotenoids in animals and cellular systems.

A large number of studies have indicated that carotenoid pigments act as anticarcinogenic agents in animals treated with either ultraviolet light, ultraviolet light with chemicals, or with chemical carcinogens alone. Although pharmacological doses of cartenoids were used in the early experiments, more recent evidence indicates that relatively small doses can be effective. These studies have been complemented by investigations in bacteria and mammalian tissue, either in cell culture or in organ culture, where it has been demonstrated that various carotenoid pigments can prevent mutagenesis, genotoxic effects, or malignant transformation. It would appear that these effects are intrinsic to the carotenoid molecule, and not necessarily due to the metabolic conversion to retinoids. Partially based on these observations, it has been suggested that carotenoid pigments may function as chemopreventive agents for reducing the risk of cancer in humans. Numerous studies are underway to test this hypothesis.