title: Urinary α-carboxyethyl hydroxychroman can be used as a predictor of α-tocopherol adequacy, as demonstrated in the Energetics Study.
abstract: BACKGROUND
  Other than the in vitro erythrocyte hemolysis test, no valid biomarkers of vitamin E status currently exist.
  
  
  OBJECTIVE
  We hypothesized that the urinary vitamin E metabolite α-carboxyethyl hydroxychroman (α-CEHC) could serve as a biomarker.
  
  
  METHODS
  The relations between urinary α-CEHC, plasma α-tocopherol, and vitamin E intakes were assessed by using a previously validated multipass, Web-based, 24-h self-administered dietary recall, and we concurrently collected plasma and 24-h urine samples from 233 participants of both sexes.
  
  
  RESULTS
  Median vitamin E intakes were 9.7 mg α-tocopherol/d. Intakes were correlated with plasma α-tocopherol (R = 0.40, P < 0.001) and urinary α-CEHC (R = 0.42, P < 0.001); these correlations were essentially unchanged after multivariate adjustments. On the basis of multiple regression analysis, urinary α-CEHC excretion increased by ~0.086 μmol/g creatinine (95% CI: 0.047, 0.125) for every 1-mg (2.3-μmol) increase in dietary α-tocopherol. Urinary α-CEHC excretion remained at a plateau (median: 1.39 μmol/g creatinine) until dietary intakes of α-tocopherol exceeded 9 mg α-tocopherol/d. The inflection point at which vitamin E metabolism increased was estimated to be at an intake of 12.8 mg α-tocopherol/d. Daily excretion of >1.39 μmol α-CEHC/g creatinine is associated with a greater than adequate α-tocopherol status, as evidenced by increased vitamin E metabolism and excretion.
  
  
  CONCLUSIONS
  Thus, urinary α-CEHC is a valid biomarker of α-tocopherol status that can be used to set a value for the Estimated Adequate Requirement of vitamin E.
authors.affiliation: General Internal Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Lebold
authors.forename: Alfonso
authors.initials: A
authors.lastname: Ang
authors.forename: Maret G
authors.initials: MG
authors.lastname: Traber
authors.forename: Lenore
authors.initials: L
authors.lastname: Arab
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D002839:Chromans / Q000652:urine*; D015331:Cohort Studies; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D009751:Nutritional Requirements; D009752:Nutritional Status; D011237:Predictive Value of Tests; D011795:Surveys and Questionnaires; D014810:Vitamin E / Q000008:administration & dosage / Q000378:metabolism; D014811:Vitamin E Deficiency / Q000097:blood / Q000175:diagnosis / Q000378:metabolism / Q000652:urine; D055815:Young Adult; D024502:alpha-Tocopherol / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism
chemical_list: D015415:Biomarkers; D002839:Chromans; C483420:carboxyethyl-hydroxychroman; D014810:Vitamin E; D024502:alpha-Tocopherol