title: Evaluation of the odd fatty acids 15:0 and 17:0 in serum and adipose tissue as markers of intake of milk and dairy fat.
abstract: BACKGROUND
  There is a need for biomarkers of dietary saturated fatty acids, because several diseases have been related to intake of these fatty acids.
  
  
  OBJECTIVE
  To examine the relation between intake of dairy fat and the proportion of pentadecanoic (15:0) and heptadecanoic (17:0) acid in serum and adipose tissue.
  
  
  METHODS
  Healthy men aged 21-55 y provided serum (n = 110) and adipose tissue samples (n = 107) and completed both 14 days weighed records (WR) and a 180-item food frequency questionnaire (FFQ). The proportions of 15:0 and 17:0 acid in serum and adipose tissue as measured by gas liquid chromatography were evaluated as biomarkers for fat intake from dairy products using Pearsons correlation coefficient and the method of triads.
  
  
  RESULTS
  The strongest correlation coefficients were observed between total intake of dairy fat estimated from WR and relative content of 15:0 in adipose tissue (0.52, 95% CI: 0.37, 0.65) and total serum (0.43, 95% CI 0.26, 0.57). A consistent inverse association was observed between the intake of milk fat and relative serum content of 17:0. The validity coefficients observed for the intake of dairy fat estimated from weighed records, the 180-item FFQ and by the relative content of 15:0 in serum and adipose tissue were 0.94 (95% CI: 0.68, 1.00), 0.50 (95% CI: 0.29, 0.67), 0.49 (95% CI: 0.32, 0.67) and 0.56 (95% CI: 0.28, 0.82), respectively.
  
  
  CONCLUSIONS
  Relative content of 15:0 in serum and adipose tissue may be a useful biomarker for the intake of total dairy fat, whereas FFQs and WRs may provide better estimates of the intake of fat from milk.
authors.affiliation: Department of Nutrition, Institute of Basic Medical Sciences, School of Medicine, University of Oslo, Blindern, Norway. asgeir.brevik@basalmed.uio.no
authors.forename: A
authors.initials: A
authors.lastname: Brevik
authors.forename: M B
authors.initials: MB
authors.lastname: Veierød
authors.forename: C A
authors.initials: CA
authors.lastname: Drevon
authors.forename: L F
authors.initials: LF
authors.lastname: Andersen
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry*; D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000097:blood / Q000378:metabolism; D002849:Chromatography, Gas; D003611:Dairy Products; D015930:Diet Records; D004041:Dietary Fats / Q000008:administration & dosage / Q000032:analysis* / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008892:Milk; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D004041:Dietary Fats; D005227:Fatty Acids; C117025:pentadecanoic acid; C013102:margaric acid