title: Population-based study of alpha- and gamma-tocopherol in plasma and adipose tissue as biomarkers of intake in Costa Rican adults.
abstract: BACKGROUND
  gamma-Tocopherol is the most abundant form of vitamin E in the US diet, but alpha-tocopherol concentrations are the highest in plasma and tissues. Although plasma and adipose tissue concentrations of alpha-tocopherol have been used as biomarkers of intake, the relation between gamma-tocopherol intake and concentrations in plasma and adipose tissue is unknown.
  
  
  OBJECTIVE
  Our goal was to investigate in a randomly selected population from Costa Rica whether plasma or adipose tissue concentrations of alpha- and gamma-tocopherol are suitable biomarkers of intake.
  
  
  METHODS
  A total of 361 men (x +/- SD age: 55 +/- 11 y) and 121 women (aged 59 +/- 10 y) completed a 135-item food-frequency questionnaire and provided a fasting blood sample and adipose tissue biopsy sample.
  
  
  RESULTS
  Dietary gamma-tocopherol correlated with adipose tissue (r = 0.37, P < 0.001) and plasma (r = 0.42, P < 0.001) concentrations, regardless of supplement use. Dietary alpha-tocopherol correlated poorly with adipose tissue (r = 0.15, P < 0.01) and plasma (r = 0.16, P < 0.001) concentrations, and these correlations were even lower when users of vitamin supplements (n = 24) were excluded (adipose tissue: r = 0.10, P < 0.05; plasma: r = 0.09, P < 0.05). Compared with subjects who reported palm shortening (36%) as the major type of fat used for cooking, subjects using soybean oil (52%) had higher amounts of both alpha- and gamma-tocopherol in their diets. However, only gamma-tocopherol concentrations were higher in the plasma and adipose tissue of soybean oil users.
  
  
  CONCLUSIONS
  Plasma and adipose tissue concentrations of gamma-tocopherol are equally good biomarkers of intake. The weak associations between alpha-tocopherol intake and plasma or adipose tissue concentrations suggest that these biomarkers are influenced more by factors other than alpha-tocopherol intake.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston 02115, USA.
authors.forename: A
authors.initials: A
authors.lastname: El-Sohemy
authors.forename: A
authors.initials: A
authors.lastname: Baylin
authors.forename: A
authors.initials: A
authors.lastname: Ascherio
authors.forename: E
authors.initials: E
authors.lastname: Kabagambe
authors.forename: D
authors.initials: D
authors.lastname: Spiegelman
authors.forename: H
authors.initials: H
authors.lastname: Campos
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy; D003364:Costa Rica; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage; D019587:Dietary Supplements; D005215:Fasting; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D011795:Surveys and Questionnaires; D014018:Tissue Distribution; D014810:Vitamin E / Q000008:administration & dosage* / Q000097:blood* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D004041:Dietary Fats; D014810:Vitamin E