ABSTRACT
Carotenoids, a class of yellow to deep-red pigments present in many commonly eaten
fruits
and
vegetables
, have been hypothesized to play a role in the prevention of chronic diseases such as cancer and heart disease. Most research to date has focused on the relationship between
β
-carotene and lung cancer. Lung cancer is one of the most common cancers in the United States, and
β-carotene was initially the most thoroughly studied carotenoid because of its role as a
vitamin A
precursor
(Cooper et al., 1999). Vitamin A is an essential nutrient for humans and other vertebrates. Dietary
sources of vitamin A are provided either by
retinol esters
, which are present in foods of animal origin and are hydrolyzed in the intestine to form
retinol
, or by
plant carotenoids
. More than 600 carotenoids have been identified in nature, of which 50 to 60 possess provitamin A properties and ~10 have nutritional relevance (De Flora et al., 1999).
