title: The effect of vitamin D on renin-angiotensin system activation and blood pressure: a randomized control trial.
abstract: Disruption of vitamin D signaling in rodents causes activation of the rennin-angiotensin system (RAS) and development of hypertension. Observational studies in humans found lower circulating 25-hydroxyvitamin D [25(OH)D] is associated with increased RAS activity and blood pressure (BP). We performed the first randomized control trial to investigate the effects of vitamin D supplementation on the RAS in humans.
  
  
  
  Vitamin D deficient, [25(OH)D ≤20 ng/ml), overweight individuals without hypertension were randomized into a double-blind, placebo-controlled trial of 8-weeks treatment with ergocalciferol or placebo. Kidney-specific RAS activity, measured using renal plasma flow response to captopril in high sodium balance, was assessed at baseline and 8 weeks, as was systemic RAS activity and 24-h ambulatory BP.
  
  
  
  In total, 84 participants completed the study. Mean 25[OH]D levels increased from 14.7 to 30.3 ng/ml in the ergocalciferol group, P value < 0.0001, and from 14.3 to 17.4 ng/ml in the placebo group, P value = 0.3. The renal plasma flow response to captopril was 33.9 ± 56.1 ml/min per 1.73 m at baseline and 35.7 ± 47.7 ml/min per 1.73 m at 8 weeks in the ergocalciferol group (P value = 0.83); and was 37.3 ± 46.9 ml/min per 1.73 m at baseline and 35.9 ± 26.2 ml/min per 1.73 m at 8 weeks in the placebo group (P value = 0.78). Ergocalciferol had no effect on PRA, AngII, or 24-h BP measurements.
  
  
  
  This trial found no benefit from correcting vitamin D deficiency on RAS activity or BP after 8 weeks. These findings are not consistent with the hypothesis that vitamin D is a modifiable target for lowering BP in vitamin D deficient individuals.
authors.affiliation: aRenal Division bChanning Division of Network Medicine cDivision of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Ciaran J
authors.initials: CJ
authors.lastname: McMullan
authors.forename: Lea
authors.initials: L
authors.lastname: Borgi
authors.forename: Gary C
authors.initials: GC
authors.lastname: Curhan
authors.forename: Naomi
authors.initials: N
authors.lastname: Fisher
authors.forename: John P
authors.initials: JP
authors.lastname: Forman
mesh_terms: D000328:Adult; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001795:Blood Pressure Determination; D002216:Captopril / Q000494:pharmacology; D019587:Dietary Supplements; D004311:Double-Blind Method; D004872:Ergocalciferols / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000150:complications; D012079:Renal Circulation / Q000187:drug effects*; D012084:Renin-Angiotensin System / Q000187:drug effects*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D014815:Vitamins / Q000494:pharmacology / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D000959:Antihypertensive Agents; D004872:Ergocalciferols; D014815:Vitamins; D014807:Vitamin D; D002216:Captopril; C104450:25-hydroxyvitamin D