title: Effect of soy isoflavone supplementation on nitric oxide metabolism and blood pressure in menopausal women.
abstract: BACKGROUND
  Isoflavones, having chemical structures similar to estrogens, are believed to stimulate nitric oxide production and thus lower blood pressure. The efficacy of soy isoflavone supplementation to stimulate nitric oxide production and lower blood pressure in menopausal women with high normal blood pressure remains unknown.
  
  
  OBJECTIVE
  The objective was to test the effect of soy isoflavone supplementation on nitric oxide production and blood pressure in menopausal women with high normal blood pressure.
  
  
  METHODS
  A randomized, double-blind, parallel, placebo-controlled 6-wk trial was conducted to assess the effects of daily supplementation with 80 mg soy hypocotyl isoflavones (in aglycone units) on nitric oxide metabolism and blood pressure in 24 menopausal women with 12 women per group. Changes in nitric oxide metabolism were assessed via a primed, constant-infusion protocol with [15N]arginine and [13C]- and [2H]citrulline. Changes in blood pressure and associated vascular hemodynamics were assessed via office and 24-h ambulatory blood pressure monitoring, forearm blood flow, and indexes of arterial compliance.
  
  
  RESULTS
  When compared with placebo and after control for pretreatment values, soy isoflavone supplementation had no effect on arginine flux, citrulline flux, nitric oxide synthesis, blood pressure, forearm blood flow, or estimates of arterial stiffness.
  
  
  CONCLUSIONS
  Daily supplementation with 80 mg soy hypocotyl isoflavones over a 6-wk period had no effect on nitric oxide metabolism or blood pressure and associated vascular hemodynamics in menopausal women with high normal blood pressure.
authors.affiliation: U.S. Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA. wwong@bcm.edu
authors.forename: William W
authors.initials: WW
authors.lastname: Wong
authors.forename: Addison A
authors.initials: AA
authors.lastname: Taylor
authors.forename: E O'Brian
authors.initials: EO
authors.lastname: Smith
authors.forename: Stephen
authors.initials: S
authors.lastname: Barnes
authors.forename: David L
authors.initials: DL
authors.lastname: Hachey
mesh_terms: D001794:Blood Pressure / Q000187:drug effects*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D018546:Hypocotyl; D007529:Isoflavones / Q000494:pharmacology*; D008593:Menopause / Q000187:drug effects* / Q000502:physiology; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D013025:Glycine max / Q000737:chemistry*
chemical_list: D007529:Isoflavones; D010936:Plant Extracts; D009569:Nitric Oxide