title: Relation of iron and red meat intake to blood pressure: cross sectional epidemiological study.
abstract: OBJECTIVE
  To investigate associations of dietary iron (total, haem, and non-haem), supplemental iron, and red meat with blood pressure.
  
  
  METHODS
  Cross sectional epidemiological study.
  
  
  METHODS
  17 population samples from Japan, China, the United Kingdom, and the United States participating in the international collaborative study on macro-/micronutrients and blood pressure (INTERMAP).
  
  
  METHODS
  4680 adults aged 40-59.
  
  
  METHODS
  Average of eight blood pressure readings.
  
  
  RESULTS
  In multiple linear regression analyses dietary total iron and non-haem iron were consistently inversely associated with blood pressure. With adjustment for potential non-dietary and dietary confounders, dietary total iron intake higher by 4.20 mg/4.2 MJ (2 SD) was associated with -1.39 mm Hg (P<0.01) lower systolic blood pressure. Dietary non-haem iron intake higher by 4.13 mg/4.2 MJ (2 SD) was associated with -1.45 mm Hg (P<0.001) lower systolic blood pressure. Differences were smaller for diastolic blood pressure. In most models haem iron intake from food was positively, non-significantly associated with blood pressure. Iron intake from combined diet and supplements yielded smaller associations than dietary iron alone. Red meat intake was directly associated with blood pressure; 102.6 g/24 h (2 SD) higher intake was associated with 1.25 mm Hg higher systolic blood pressure. Associations between red meat and blood pressure persisted after adjustment for multiple confounders.
  
  
  CONCLUSIONS
  Non-haem iron has a possible role in the prevention and control of adverse blood pressure levels. An unfavourable effect of red meat on blood pressure was observed. These results need confirmation including in prospective studies, clinical trials, and from experimental evidence on possible mechanisms.
authors.affiliation: Department of Epidemiology and Public Health, Imperial College London, St Mary's Campus, London W2 1PG. I.Tzoulaki@imperial.ac.uk
authors.forename: Ioanna
authors.initials: I
authors.lastname: Tzoulaki
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Brown
authors.forename: Queenie
authors.initials: Q
authors.lastname: Chan
authors.forename: Linda
authors.initials: L
authors.lastname: Van Horn
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ueshima
authors.forename: Liancheng
authors.initials: L
authors.lastname: Zhao
authors.forename: Jeremiah
authors.initials: J
authors.lastname: Stamler
authors.forename: Paul
authors.initials: P
authors.lastname: Elliott
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006418:Heme / Q000032:analysis; D006801:Humans; D006973:Hypertension / Q000209:etiology*; D019266:Iron, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D016014:Linear Models; D008297:Male; D008461:Meat Products / Q000009:adverse effects*; D008875:Middle Aged
chemical_list: D019266:Iron, Dietary; D006418:Heme