Daily blueberry consumption improves blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension: a randomized, double-blind, placebo-controlled clinical trial

J Acad Nutr Diet. 2015 Mar;115(3):369-77. doi: 10.1016/j.jand.2014.11.001. Epub 2015 Jan 8.

Abstract

Background: Postmenopausal women have a high prevalence of hypertension and often develop arterial stiffness thereby increasing cardiovascular disease risk. Although antihypertensive drug therapies exist, increasing numbers of people prefer natural therapies. In vivo studies and a limited number of clinical studies have demonstrated the antihypertensive and vascular-protective effects of blueberries.

Objective: To examine the effects of daily blueberry consumption for 8 weeks on blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension.

Design: This was an 8-week, randomized, double-blind, placebo-controlled clinical trial.

Participants/setting: Forty-eight postmenopausal women with pre- and stage 1-hypertension recruited from the greater Tallahassee, FL, area participated.

Intervention: Participants were randomly assigned to receive either 22 g freeze-dried blueberry powder or 22 g control powder.

Main outcome measures: Resting brachial systolic and diastolic blood pressures were evaluated and arterial stiffness was assessed using carotid-femoral pulse wave velocity and brachial-ankle pulse wave velocity. C-reactive protein, nitric oxide, and superoxide dismutase were measured at baseline, 4 weeks, and 8 weeks.

Statistical analyses performed: Statistical analysis was performed using a split plot model of repeated measures analysis of variance.

Results: After 8 weeks, systolic blood pressure and diastolic blood pressure (131±17 mm Hg [P<0.05] and 75±9 mm Hg [P<0.01], respectively) and brachial-ankle pulse wave velocity (1,401±122 cm/second; P<0.01) were significantly lower than baseline levels (138±14 mm Hg, 80±7 mm Hg, and 1,498±179 cm/second, respectively), with significant (P<0.05) group×time interactions in the blueberry powder group, whereas there were no changes in the group receiving the control powder. Nitric oxide levels were greater (15.35±11.16 μmol/L; P<0.01) in the blueberry powder group at 8 weeks compared with baseline values (9.11±7.95 μmol/L), whereas there were no changes in the control group.

Conclusions: Daily blueberry consumption may reduce blood pressure and arterial stiffness, which may be due, in part, to increased nitric oxide production.

Trial registration: ClinicalTrials.gov NCT01686282.

Keywords: Blueberries; Flavonoids; Nitric oxide; Pulse wave velocity; Vasodilation.

Publication types

  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Ankle Brachial Index
  • Blood Pressure / physiology
  • Blueberry Plants*
  • C-Reactive Protein / metabolism
  • Double-Blind Method
  • Female
  • Florida
  • Fruit*
  • Humans
  • Hypertension / blood
  • Hypertension / diet therapy*
  • Hypertension / physiopathology
  • Middle Aged
  • Nitric Oxide / blood
  • Pulse Wave Analysis
  • Superoxide Dismutase / blood
  • Vascular Stiffness / physiology

Substances

  • Nitric Oxide
  • C-Reactive Protein
  • Superoxide Dismutase

Associated data

  • ClinicalTrials.gov/NCT01686282