title: Twenty-four hour urinary urea excretion and 9-year risk of hypertension: the PREVEND study.
abstract: OBJECTIVE
  It is not yet clear whether dietary protein could help maintaining a healthy blood pressure (BP). We investigated the association between total protein intake, estimated from 24-h urinary urea excretion, and incident hypertension in Dutch men and women.
  
  
  METHODS
  We analyzed data of 3997 men and women (aged 28-75 years) who participated in the Prevention of Renal and Vascular Endstage Disease (PREVEND) study, a prospective cohort study. Urea excretion was assessed in two consecutive 24-h urine collections at baseline and approximately 4 years later, from which total protein intake was estimated using the Maroni method. Participants were followed for 9 years for hypertension incidence, defined as BP at least 140/90 mmHg or initiation of antihypertensive medication. Hazard ratios (HR) were obtained in sex-specific quintiles of protein intake using time-dependent Cox regression, adjusted for age, sex, BMI, smoking, alcohol use, and 24-h urinary excretions of sodium and potassium.
  
  
  RESULTS
  Baseline BP was on average 119/70 mmHg and 976 participants developed hypertension during follow-up. Mean protein intake (in g/kg ideal body weight) was 1.18 ± 0.26 for men and 1.12 ± 0.25 for women. Estimated protein intake was nonlinearly inversely associated with incident hypertension in the fully adjusted model, with nonsignificant HR of 0.77, 0.75, 0.82, and 0.83 in consecutive quintiles compared with the lowest quintile (P-trend: 0.52).
  
  
  CONCLUSIONS
  Protein intake, as assessed by urinary urea excretion, was not significantly associated with 9-year hypertension incidence in Dutch men and women.
authors.affiliation: Top Institute Food and Nutrition bDivision of Human Nutrition, Wageningen University, Wageningen, The Netherlands. susanne.tielemans@wur.nl
authors.forename: Susanne M A J
authors.initials: SM
authors.lastname: Tielemans
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Geleijnse
authors.forename: Marleen A
authors.initials: MA
authors.lastname: van Baak
authors.forename: Mariëlle F
authors.initials: MF
authors.lastname: Engberink
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Brink
authors.forename: Paul E
authors.initials: PE
authors.lastname: de Jong
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Gansevoort
authors.forename: Stephan J L
authors.initials: SJ
authors.lastname: Bakker
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure; D015992:Body Mass Index; D004032:Diet; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000652:urine*; D007676:Kidney Failure, Chronic / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011188:Potassium / Q000652:urine; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012964:Sodium / Q000652:urine; D014508:Urea / Q000652:urine*
chemical_list: D014508:Urea; D012964:Sodium; D011188:Potassium