Carotenoids and health risk
INTRODUCTION In recent years, carotenoids have both been hailed as miracle nutrients and viewed with skepticism regarding their actual impact on health. Although observational epidemiologic studies show a consistent inverse association between fruit and vegetable intake and the risk of several cancers, cardiovascular disease, and agerelated macular degeneration, ^-carotene (BC) intervention trials in smokers did not result in reduced risk of lung cancer or cardiovascular disease. This mixture of optimism and uncertainty stems from the limited knowledge about the absorption, transport, utilization, and effect of carotenoids in human tissues. The study of carotenoids has proceeded steadily, but slowly, as carotenoids are delicate compounds making research on their chemical structure and behavior arduous. Also, observational epidemiologic studies evaluating the consumption of whole foods do not allow us to know with certainty whether the results are due to the carotenoid content of certain foods, other components of the whole food, or a combination of interacting factors. In addition, the human absorption of intact carotenoids is unique and not easily replicated in animal models.