Carotenoid and retinoid metabolism: insights from isotope studies.
Use of isotopes as tracers has had an important role in elucidating key features of vitamin A and retinoid metabolism in animal models and humans. Their use has shown that beta-carotene absorption is variable, and that the appearance of beta-carotene and its metabolites in the blood by time since dosing follows characteristic patterns. Retinol formed from beta-carotene shows a different pattern, as does lutein. In this article, we summarize and discuss insights and some surprises into the absorption and metabolism of vitamin A, beta-carotene, and lutein that were gained with the use of isotope tracers in humans, rats, and cells as models.
Burri
Betty J
BJ
Western Human Nutrition Research Center, ARS/USDA, Davis, CA 95616, USA.
Clifford
Andrew J
AJ
D000818:Animals; D002338:Carotenoids / Q000378:metabolism*; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D009752:Nutritional Status; D010315:Particle Accelerators; D012176:Retinoids / Q000378:metabolism*; D019207:beta Carotene / Q000378:metabolism / Q000493:pharmacokinetics
D012176:Retinoids; D019207:beta Carotene; D002338:Carotenoids