title: Moderate salt restriction effectively lowers blood pressure and degree of salt sensitivity is related to baseline concentration of renin and N-terminal atrial natriuretic peptide in plasma.
abstract: OBJECTIVE
  The effect of salt restriction on blood pressure is under intense debate. We tested the effect of 100 mmol salt reduction on ambulatory blood pressure (ABP) in 46 Swedish individuals, 39 of whom completed the study, using a double-blind, placebo-controlled, cross-over design. Furthermore, we tested whether the basal plasma concentration of renin or N-terminal atrial natriuretic peptide (Nt-proANP) predict the degree of salt sensitivity.
  
  
  METHODS
  Participants received all meals and drinks with a total daily NaCl content of 50 mmol during 8 weeks. In addition, NaCl capsules (100 mmol/day) and corresponding placebo capsules were administered for 4 weeks each in random order. ABP after high-salt intake (150 mmol/day) was compared with ABP after low-salt intake (50 mmol/day). Salt sensitivity was defined as the difference between 24-h systolic ABP at the high-salt versus the low-salt periods. Baseline renin and Nt-proANP were related to salt sensitivity.
  
  
  RESULTS
  Lowering of salt intake from 150 to 50 mmol/day induced significant blood pressure reductions (mean reduction, 95% confidence interval) in systolic and diastolic 24-h ABP (5.8, 3.4-8.2 and 2.6, 0.91-4.4 mmHg), daytime ABP (5.5, 2.9-8.1 and 2.3, 0.42-4.1 mmHg) and night-time ABP (6.4, 3.5-9.3 and 3.4, 1.4-5.5 mmHg). Baseline ln(renin) correlated inversely with salt sensitivity (r = -0.50, P = 0.001) whereas baseline ln(Nt-proANP) correlated directly (r = 0.33, P = 0.04).
  
  
  CONCLUSIONS
  Lowering of salt intake with 100 mmol/day induces clinically relevant ABP reductions. Renin and Nt-proANP, measured with individuals on their habitual diet, could be useful biomarkers to identify individuals with the greatest blood pressure-lowering benefit from reduced salt intake.
authors.affiliation: Department of Clinical Sciences, Malmö University Hospital and Lund University, Malmö, Sweden. olle.melander@med.lu.se
authors.forename: Olle
authors.initials: O
authors.lastname: Melander
authors.forename: Fredrik
authors.initials: F
authors.lastname: von Wowern
authors.forename: Erik
authors.initials: E
authors.lastname: Frandsen
authors.forename: Philippe
authors.initials: P
authors.lastname: Burri
authors.forename: Gunilla
authors.initials: G
authors.lastname: Willsteen
authors.forename: Mattias
authors.initials: M
authors.lastname: Aurell
authors.forename: U Lennart
authors.initials: UL
authors.lastname: Hulthén
mesh_terms: D009320:Atrial Natriuretic Factor / Q000097:blood; D015415:Biomarkers; D001794:Blood Pressure / Q000187:drug effects*; D018660:Blood Pressure Monitoring, Ambulatory; D018592:Cross-Over Studies; D004039:Diet, Sodium-Restricted; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006973:Hypertension / Q000178:diet therapy*; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D017673:Sodium Chloride, Dietary; D009320:Atrial Natriuretic Factor; D012083:Renin