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NCT Number: NCT01686282

Blueberry Consumption Improves Vascular Function and Lowers Blood Pressure in Postmenopausal Women With Pre- and Stage 1-hypertension

Cardiovascular disease (CVD) continues to be the leading cause of death in the U.S. Americans have been more concerned about their blood cholesterol levels and dietary cholesterol intakes rather than their overall cardiovascular health risk factors leading to CVD such as hypertension, vascular dysfunction, inadequate consumption of fruits and vegetables and physical activity. Statistics show that approximately 91% of individuals with CVD have vascular dysfunction which is attributed to endothelial and autonomic dysfunction leading to increased arterial stiffness.

The investigators long-term goal is to provide feasible and effective dietary ways for pre- and stage 1- hypertensive individuals to normalize their blood pressure (BP), improve vascular function and thereby reducing their cardiovascular risk and enhancing the quality of life. Blueberries are a rich source of phenolic compounds and these compounds may play an important role in promoting cardiovascular health. Considering the strong possibility that phytochemicals present in blueberry work additively or synergistically, it would be ideal to investigate the cardioprotective effects of blueberry as a whole. The investigators overall objective to bring forth evidence that blueberry consumption will reduce BP and cardiovascular risk factors including endothelial dysfunction, arterial stiffness, and autonomic dysfunction in pre- and stage 1-hypertensive postmenopausal women. The investigators hypothesize that blueberry supplementation will improve vascular function and will lower blood pressure in postmenopausal women with pre-hypertension. The findings of this study will provide a foundation for disseminating feasible, safe approaches for preventing and combating hypertension at its early stage which does not require drug therapy.

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Key information

Conditions

Blood Pressure Cardiovascular Diseases Hypertension Vascular Diseases

Age range

45 year–65 year

Sex eligibility

Female

Study type

Interventional

Phase

Phase 2

Primary location

The Department of Nutrition, Food, and Exercise Sciences, Florida State University

Tallahassee, Florida, 32306, United States

About this study

The purpose of this study is to examine the effects of 22 grams of freeze-dried blueberry intake on a daily basis for eight weeks in:

The purpose of the study is to examine the effects of 22 grams of freeze-dried blueberry intake on a daily basis for eight weeks on arterial function and blood pressure in postmenopausal women with pre- and stage 1-hypertension. The specific aims of the study are:

  • To investigate the extent to which daily consumption of 22 g blueberry drink-mix reduces blood pressure in individuals with pre- and stage 1-hypertension.
  • To determine whether daily consumption of 22 g blueberry drink-mix will improve the autonomic control of blood pressure and heart rate in individuals with pre- and stage 1-hypertension.
  • To measure serum markers of oxidative stress to determine whether increased antioxidant defense is in part responsible for blueberry's vascular protective effects.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 40 women (1 to 10 years after natural menopause or bilateral oophorectomy) 45-65 years of age.
  • Seated blood pressure ≥ 130/85 mm Hg but ≤ 160/90 mm Hg.

Exclusion criteria

  • Blood pressure >160/100 mmHg
  • Taking insulin
  • Cardiovascular disease
  • Active cancer
  • Asthma
  • Glaucoma
  • Thyroid disease
  • Kidney disease
  • Liver disease
  • Pancreatic disease
  • Enrollment in a weight loss program
  • Heavy smokers (>20 cigarettes per day)

Treatment and study plan

Freeze-dried Blueberry Powder

Dietary Supplement

8 weeks of freeze-dried taken in two doses of 22g each per day.

Other names: U.S. Highbush Blueberry Council

Placebo

Dietary Supplement

8 weeks of freeze-dried taken in two doses of 22g each per day.

Primary outcomes

  1. Blood Pressure

    Time frame: 8 weeks

    By measuring aortic blood pressure at rest and during physiological stress (handgrip exercise and post-exercise muscle ischemia).

Secondary outcomes

  1. Autonomic Control of Blood Pressure

    Time frame: 8 weeks

    By measuring blood pressure variability and baroreflex sensitivity at rest and during physiological stress.

  2. Autonomic Control of Heart Rate

    Time frame: 8 weeks

    By measuring heart rate variability at rest and during physiological stress.

  3. Endothelial Function

    Time frame: 8 week

    By measuring markers of vascular inflammation (adiponectin, leptin, endothelin-1, angiotensin II and 8-isoprostane).

  4. Inflammation

    Time frame: 8 weeks

    By measuring a marker of inflammation (tumor necrosis factor-α [TNF-α]).

  5. Oxidative Stress

    Time frame: 8 weeks

    By measuring markers of oxidative stress (superoxide dismutase [SOD], nitrate/nitrite [NOx], ET-1, angiotensin II, 8-isoprostane, MDA, and oxidized LDL).

  6. Arterial Stiffness

    Time frame: 8 Week

    By measuring the augmentation index and arterial stiffness at rest and during physiological stress (handgrip exercise and post-exercise muscle ischemia).

Sponsors and collaborators

Lead sponsor

Florida State University

Other

Collaborators

  • U.S. Highbush Blueberry Council

Registry information

Official study title

Daily Incorporation of Blueberries Into a Diet Favorably Improves Vascular Function and Lowers Aortic Blood Pressure in Postmenopausal Women With Pre- and Stage 1-hypertension.

Important dates

Study start
2012
Primary completion
2013
Study completion
2014
First posted
Sep 18, 2012
Registry last updated
Jan 14, 2015

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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