Functions and Actions of Retinoids and Carotenoids: Building on the Vision of James

Dr. James Allen Olson helped us to define the role of beta-carotene in human health by categorizing these as “functions, actions and associations.” In the last decade, significant research has shown that betacarotene acts as an antioxidant in biologically relevant systems, affects several aspects of human immune function and higher intake/serum levels are associated with improvements in certain physiological functions such as lung function. The unexpected findings of increased lung cancer in beta-carotene supplemented smokers in the ATBC and CARET intervention studies have resulted in the need for expanded research efforts to define the mechanism(s) of action of beta-carotene. Recent survey data as well as laboratory animal studies continue to find an inverse association between beta-carotene and cancer risk. Because beta-carotene is the major source of vitamin A for the majority of the world’s population, it is critical to define the safe levels of intake from foods and supplements. J. Nutr. 134: 225S–230S, 2004.