title: Vitamin D status and PUFA ratios in a national representative cross-section of healthy, middle-aged Norwegian women—the Norwegian Women and Cancer Post-Genome Cohort.
abstract: OBJECTIVE
  Vitamin D and polyunsaturated fatty acids (PUFAs) are derived from partially overlapping sources. Vitamin D is produced in the skin after sun exposure, but is also derived from fatty fish and fish oils. Dietary PUFAs are mainly derived from plant oils that are rich in n-6 PUFAs, but fatty fish provides high amounts of the marine n-3 PUFAs. The Western diet provides an excess of n-6 PUFAs compared to n-3 PUFAs, and the ratios of these may influence human health. Here, we investigated the potential associations of plasma concentrations of vitamin D, marine PUFAs and PUFA ratios.
  
  
  METHODS
  Plasma concentrations of vitamin D (25(OH)D), marine PUFAs, and PUFA ratios were measured in 372 women from the Norwegian Women and Cancer (NOWAC) Post-Genome Cohort. Covariability was examined in 310 non-users of cod liver oil, using Spearman's rank correlation and linear regression.
  
  
  RESULTS
  In non-users of cod liver oil, the average concentration of vitamin D was 40.3 nmol/L, and marine PUFA concentration was 0.2 mg/g. PUFA ratios were dominated by the n-6 fatty acids. Vitamin D levels were significantly associated with marine fatty acids and weakly associated with PUFA ratios.
  
  
  CONCLUSIONS
  Concentrations of vitamin D and marine PUFAs were below recommended levels. The correlation analyses indicated that health-related effects of vitamin D and marine PUFAs respectively may be hard to separate in epidemiological studies. However, measured health effects of PUFA ratios and vitamin D are likely to derive from the influence of the two factors separately. The presented results are the first to show these associations in a nationally representative cohort.
authors.affiliation: Department of Community Medicine, UiT The Arctic University of Norway, Tromsø, Norway karina.s.olsen@uit.no.
authors.forename: Karina Standahl
authors.initials: KS
authors.lastname: Olsen
authors.affiliation: Departments of Clinical Science Section for Paediatrics, Haukeland University Hospital, Bergen, Norway.
authors.forename: Lage
authors.initials: L
authors.lastname: Aksnes
authors.affiliation: Biomedicine, University of Bergen, Bergen, Norway.
authors.forename: Livar
authors.initials: L
authors.lastname: Frøyland
authors.affiliation: Department of Community Medicine, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Eiliv
authors.initials: E
authors.lastname: Lund
authors.affiliation: Department of Community Medicine, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Charlotta
authors.initials: C
authors.lastname: Rylander
mesh_terms: D000818:Animals; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004032:Diet / Q000706:statistics & numerical data; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage / Q000032:analysis / Q000097:blood*; D005260:Female; D005399:Fishes; D006801:Humans; D008875:Middle Aged; D009664:Norway; D014807:Vitamin D / Q000008:administration & dosage / Q000097:blood*
chemical_list: D005231:Fatty Acids, Unsaturated; D014807:Vitamin D
keywords: Fatty acids; PUFA; epidemiology; fatty fish; nutrition; vitamin D