Carotenoids

Abstract

Carotenoids—plant pigments that are generally found in fruits and vegetables are widespread in plants and in photosynthetic bacteria, where they serve two essential functions: as accessory pigments in photosynthesis and in photoprotection. These two functions are a result of the conjugated polyene structure of carotenoids (Fig. 1), which allows the molecule to absorb light and quench, or inactivate, singlet oxygen and free radicals. Although several hundred different carotenoids are found in nature, humans generally ingest and absorb significant quantities of relatively few carotenoids, particularly lycopene, 13- and a-carotene, lutein, zeaxanthin, and (3-cryptoxanthin. The carotenoid profile of an individual’s blood is a reflection of the carotenoid composition of that individual’s diet. Normative intake data and plasma concentrations from the Third National Health and Nutrition Examination Survey in the United States (NHANES III) have been made available for these carotenoids (1, 2), as shown in Table 1. Lycopene, a red pigment derived almost exclusively from tomatoes/tomato products, is the predominant carotenoid in the United States population as a whole. Persons in the United States generally consume substantial quantities of foods containing tomato products, such as pastas with tomato sauce, pizza, and lasagna. In countries where tomatoes are not widely con- sumed, lycopene concentrations in blood can be low relative to other carotenoids.