title: Modulation of plasma all-trans retinoic acid concentrations by the consumption of carotenoid-rich vegetables.
abstract: OBJECTIVE
  A human intervention trial was conducted to determine the effects of consumption of carotenoid-rich vegetables on levels of retinol (ROL) and the active vitamin A metabolite all-trans retinoic acid (ATRA).
  
  
  METHODS
  The study was divided into four periods, each lasting 2 wk: weeks 1-2, a low carotenoid period; weeks 3-4, daily consumption of 330 mL of tomato juice; weeks 5-6, 330 mL of carrot juice daily; and weeks 7-8, 10 g of dried spinach powder daily. ROL and ATRA concentrations were measured after each 2-wk study period.
  
  
  CONCLUSIONS
  This study shows that consumption of carrot juice containing high concentrations of the pro-vitamin A carotenoid beta-carotene results in slightly, non-significantly increased plasma ROL concentrations and strong, significantly increased (almost double, from 1.2 +/- 0.3 to 2.0 +/- 0.31 ng/mL) plasma concentrations of ATRA, whereas consumption of tomato juice and spinach powder results in no significant alteration in concentrations of plasma ROL and ATRA.
authors.affiliation: Apoptosis and Genomics Research Center, Hungarian Academy of Sciences, Laboratory of Nutritional Bioactivation and Bioanalysis, Department of Biochemistry and Molecular Biology, University of Debrecen, Debrecen, Hungary. rruehl@dote.hu
authors.forename: Ralph
authors.initials: R
authors.lastname: Rühl
authors.forename: Achim
authors.initials: A
authors.lastname: Bub
authors.forename: Bernhard
authors.initials: B
authors.lastname: Watzl
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000975:Antioxidants / Q000378:metabolism; D002338:Carotenoids / Q000008:administration & dosage* / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D018592:Cross-Over Studies; D018552:Daucus carota / Q000737:chemistry*; D006801:Humans; D008297:Male; D014212:Tretinoin / Q000097:blood*; D014675:Vegetables / Q000737:chemistry; D019207:beta Carotene / Q000097:blood
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D002338:Carotenoids; D014212:Tretinoin