title: Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of α-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort.
abstract: BACKGROUND
  Intakes of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) are important for health. Because fish is the major source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), non-fish-eaters may have suboptimal n-3 PUFA status, although the importance of the conversion of plant-derived α-linolenic acid (ALA) to EPA and DHA is debated.
  
  
  OBJECTIVE
  The objective was to determine intakes, food sources, and status of n-3 PUFAs according to dietary habit (fish-eaters and non-fish-eating meat-eaters, vegetarians, or vegans) and estimated conversion between dietary ALA and circulating long-chain n-3 PUFAs.
  
  
  METHODS
  This study included 14,422 men and women aged 39-78 y from the EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk cohort with 7-d diary data and a substudy in 4902 individuals with plasma phospholipid fatty acid measures. Intakes and status of n-3 PUFAs were measured, and the product-precursor ratio [corrected] of ALA to circulating n-3 PUFAs was calculated.
  
  
  RESULTS
  Most of the dietary intake of EPA and DHA was supplied by fish; however, meat was the major source in meat-eaters, and spreading fats, soups, and sauces were the major sources in vegetarians. Total n-3 PUFA intakes in non-fish-eaters were 57-80% of those in fish-eaters, but status differences were considerably smaller [corrected]. The estimated product-precursor ratio [corrected] was greater in women than in men and greater in non-fish-eaters than in fish-eaters.
  
  
  CONCLUSIONS
  Substantial differences in intakes and in sources of n-3 PUFAs existed between the dietary-habit groups, but the differences in status were smaller than expected, possibly because the product-precursor ratio [corrected] was greater in non-fish-eaters than in fish-eaters, potentially indicating increased estimated conversion of ALA. If intervention studies were to confirm these findings, it could have implications for fish requirements.
authors.affiliation: School of Medicine Health Policy and Practice, University of East Anglia, Norwich, United Kingdom. a.welch@uea.ac.uk
authors.forename: Ailsa A
authors.initials: AA
authors.lastname: Welch
authors.forename: Subodha
authors.initials: S
authors.lastname: Shakya-Shrestha
authors.forename: Marleen A H
authors.initials: MA
authors.lastname: Lentjes
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Wareham
authors.forename: Kay-Tee
authors.initials: KT
authors.lastname: Khaw
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D015331:Cohort Studies; D004032:Diet; D015930:Diet Records; D014676:Diet, Vegetarian; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000096:biosynthesis / Q000097:blood; D005260:Female; D005399:Fishes; D006801:Humans; D008297:Male; D008460:Meat; D008875:Middle Aged; D017747:Seafood; D012737:Sex Factors; D017962:alpha-Linolenic Acid / Q000378:metabolism*
chemical_list: D015525:Fatty Acids, Omega-3; D017962:alpha-Linolenic Acid