Absorption, transport, and metabolism of carotenoids in humans

Abstract

Vitamin A, which is an essential nutrient for humans, may be provided in the diet either as preformed vitamin A or as provitamin A carotenoids. The bioavailability of carotenoids in foods varies greatly, depending on many factors. Carotenoids are emulsified and then are solubilized in micellar form within the intestine with an absolute requirement for conjugated bile salts. Dietary carotenoids are absorbed as part of chylomicra, but in the steady state they are primarily constituents of low density and high density lipoproteins. Carotenoids are metabolized in many different ways, depending on their structure. Of particular importance nutritionally is the conversion of provitamin A carotenoids to vitamin A. Carotenoids are found in nearly all tissues, but, particularly, in the liver and adipose tissue. Each carotenoid shows individual features relative to its absorption, transport, and metabolism. © 1994 IUPAC