title: Absorption and Distribution Kinetics of the 13C-Labeled Tomato Carotenoid Phytoene in Healthy Adults.
abstract: BACKGROUND
  Phytoene is a tomato carotenoid that may contribute to the apparent health benefits of tomato consumption. Although phytoene is a less prominent tomato carotenoid than lycopene, it is a major carotenoid in various human tissues. Phytoene distribution to plasma lipoproteins and tissues differs from lycopene, suggesting the kinetics of phytoene and lycopene differ.
  
  
  OBJECTIVE
  The objective of this study was to characterize the kinetic parameters of phytoene absorption, distribution, and excretion in adults, to better understand why biodistribution of phytoene differs from lycopene.
  
  
  METHODS
  Four adults (2 males, 2 females) maintained a controlled phytoene diet (1-5 mg/d) for 42 d. On day 14, each consumed 3.2 mg (13)C-phytoene, produced using tomato cell suspension culture technology. Blood samples were collected at 0, 1-15, 17, 21, and 24 h and 2, 3, 4, 7, 10, 14, 17, 21, and 28 d after (13)C-phytoene consumption. Plasma-unlabeled and plasma-labeled phytoene concentrations were determined using ultra-HPLC-quadrupole time-of-flight-mass spectrometry, and data were fit to a 7-compartment carotenoid kinetic model using WinSAAM 3.0.7 software.
  
  
  RESULTS
  Subjects were compliant with a controlled phytoene diet, consuming a mean ± SE of 2.5 ± 0.6 mg/d, resulting in a plasma unlabeled phytoene concentration of 71 ± 14 nmol/L. A maximal plasma (13)C-phytoene concentration of 55.6 ± 5.9 nM was achieved 19.8 ± 9.2 h after consumption, and the plasma half-life was 2.3 ± 0.2 d. Compared with previous results for lycopene, phytoene bioavailability was nearly double at 58% ± 19%, the clearance rate from chylomicrons was slower, and the rates of deposition into and utilization by the slow turnover tissue compartment were nearly 3 times greater.
  
  
  CONCLUSIONS
  Although only differing from lycopene by 4 double bonds, phytoene exhibits markedly different kinetic characteristics in human plasma, providing insight into metabolic processes contributing to phytoene enrichment in plasma and tissues compared with lycopene. This trial was registered at clinicaltrials.gov as NCT01692340.
authors.affiliation: The Ohio State University Comprehensive Cancer Center.
authors.forename: Nancy E
authors.identifier: http://orcid.org/0000-0001-7281-9187
authors.initials: NE
authors.lastname: Moran
authors.affiliation: Human Nutrition Research Center, USDA, Beltsville, MD; and.
authors.forename: Janet A
authors.identifier: http://orcid.org/0000-0002-9121-886X
authors.initials: JA
authors.lastname: Novotny
authors.affiliation: Department of Food Science and Technology, and.
authors.forename: Morgan J
authors.identifier: http://orcid.org/0000-0001-9379-0264
authors.initials: MJ
authors.lastname: Cichon
authors.affiliation: The Ohio State University Comprehensive Cancer Center, Department of Food Science and Technology, and.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Riedl
authors.affiliation: Department of Food Science and Human Nutrition and Division of Nutritional Sciences, University of Illinois, Urbana, IL.
authors.forename: Randy B
authors.initials: RB
authors.lastname: Rogers
authors.affiliation: The Ohio State University Comprehensive Cancer Center.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Grainger
authors.affiliation: The Ohio State University Comprehensive Cancer Center, Department of Food Science and Technology, and.
authors.forename: Steven J
authors.identifier: http://orcid.org/0000-0002-1427-5780
authors.initials: SJ
authors.lastname: Schwartz
authors.affiliation: Department of Food Science and Human Nutrition and Division of Nutritional Sciences, University of Illinois, Urbana, IL.
authors.forename: John W
authors.initials: JW
authors.lastname: Erdman
authors.affiliation: The Ohio State University Comprehensive Cancer Center, The James Cancer Hospital and Department of Internal Medicine-Division of Medical Oncology, The Ohio State University, Columbus, OH; Steven.Clinton@osumc.edu.
authors.forename: Steven K
authors.initials: SK
authors.lastname: Clinton
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism / Q000493:pharmacokinetics*; D001682:Biological Availability; D002247:Carbon Isotopes; D002338:Carotenoids / Q000097:blood / Q000493:pharmacokinetics*; D004032:Diet; D005260:Female; D006207:Half-Life; D006801:Humans; D007408:Intestinal Absorption; D007700:Kinetics; D000077276:Lycopene; D018551:Solanum lycopersicum / Q000737:chemistry*; D008297:Male; D014018:Tissue Distribution
chemical_list: D000975:Antioxidants; D002247:Carbon Isotopes; D002338:Carotenoids; C100185:(all-E) phytoene; D000077276:Lycopene
keywords: carotenoid; compartmental modeling; kinetics; phytoene; tomato