title: Plasma concentrations and intakes of amino acids in male meat-eaters, fish-eaters, vegetarians and vegans: a cross-sectional analysis in the EPIC-Oxford cohort.
abstract: OBJECTIVE
  We aimed to investigate the differences in plasma concentrations and in intakes of amino acids between male meat-eaters, fish-eaters, vegetarians and vegans in the Oxford arm of the European Prospective Investigation into Cancer and Nutrition.
  
  
  METHODS
  This cross-sectional analysis included 392 men, aged 30-49 years. Plasma amino acid concentrations were measured with a targeted metabolomic approach using mass spectrometry, and dietary intake was assessed using a food frequency questionnaire. Differences between diet groups in mean plasma concentrations and intakes of amino acids were examined using analysis of variance, controlling for potential confounding factors and multiple testing.
  
  
  RESULTS
  In plasma, concentrations of 6 out of 21 amino acids varied significantly by diet group, with differences of -13% to +16% between meat-eaters and vegans. Concentrations of methionine, tryptophan and tyrosine were highest in fish-eaters and vegetarians, followed by meat-eaters, and lowest in vegans. A broadly similar pattern was seen for lysine, whereas alanine concentration was highest in fish-eaters and lowest in meat-eaters. For glycine, vegans had the highest concentration and meat-eaters the lowest. Intakes of all 18 dietary amino acids differed by diet group; for the majority of these, intake was highest in meat-eaters followed by fish-eaters, then vegetarians and lowest in vegans (up to 47% lower than in meat-eaters).
  
  
  CONCLUSIONS
  Men belonging to different habitual diet groups have significantly different plasma concentrations of lysine, methionine, tryptophan, alanine, glycine and tyrosine. However, the differences in plasma concentrations were less marked than and did not necessarily mirror those seen for amino acid intakes.
authors.affiliation: Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Schmidt
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: S
authors.initials: S
authors.lastname: Rinaldi
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: A
authors.initials: A
authors.lastname: Scalbert
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: P
authors.initials: P
authors.lastname: Ferrari
authors.affiliation: International Agency for Research on Cancer, Lyon, France.
authors.forename: D
authors.initials: D
authors.lastname: Achaintre
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gunter
authors.affiliation: Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: P N
authors.initials: PN
authors.lastname: Appleby
authors.affiliation: Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Key
authors.affiliation: Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Travis
mesh_terms: D000328:Adult; D000409:Alanine / Q000097:blood; D000596:Amino Acids / Q000097:blood*; D000818:Animals; D003430:Cross-Sectional Studies; D000067269:Diet, Vegan; D014676:Diet, Vegetarian; D002149:Energy Intake; D005399:Fishes; D005998:Glycine / Q000097:blood; D006801:Humans; D008239:Lysine / Q000097:blood; D008297:Male; D008460:Meat; D008715:Methionine / Q000097:blood; D008875:Middle Aged; D017747:Seafood; D011795:Surveys and Questionnaires; D014364:Tryptophan / Q000097:blood; D014443:Tyrosine / Q000097:blood
chemical_list: D000596:Amino Acids; D014443:Tyrosine; D014364:Tryptophan; D008715:Methionine; D008239:Lysine; D000409:Alanine; D005998:Glycine