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Clinical Trial of Dietary Protein and Blood Pressure (ProBP)

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00046566
First Posted: October 1, 2002
Last Update Posted: July 24, 2017
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Collaborator:
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Jiang He, MD, PhD, Tulane University
  Purpose
The purpose of this study is to examine the effect of dietary protein supplements on high blood pressure (BP).

Condition Intervention
Cardiovascular Diseases Hypertension Heart Diseases Dietary Supplement: Soy protein-milk protein-carbohydrate Dietary Supplement: Milk protein-carbohydrate-soy protein Behavioral: Carbohydrate-soy protein-milk protein

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description:
The trial participants were assigned to take 40 g/d soy protein, milk protein, or carbohydrate supplementation each for 8 weeks in a random order. A 3-week washout period was implemented between the interventions.
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Masking Description:
The randomization assignment list was generated by a computer program that could only be accessed by the study data coordinator. Apart from the data coordinator, all research personnel, including study coordinators and BP technicians, and the study participants were unaware of treatment assignment.
Primary Purpose: Prevention
Official Title: Clinical Trial of Dietary Protein on Blood Pressure

Resource links provided by NLM:


Further study details as provided by Jiang He, MD, PhD, Tulane University:

Primary Outcome Measures:
  • Change From Baseline in Average Systolic Blood Pressure at 8 Weeks [ Time Frame: Every 8 weeks ]
    The change of systolic blood pressure was calculated as the mean of 6 blood pressure values from two 8-week visits minus the mean of 6 values from two baseline visits within each intervention phase. At each visit, 3 BP values were measured with a Hawksley random-zero sphygmomanometer by trained and certified observers who were masked to group assignment. BP readings were taken from the right arm with appropriately sized cuffs after the participant had been seated quietly for 5 minutes. The participant was instructed not to eat, smoke, drink alcohol, or exercise for at least 30 minutes before their BP measurements.


Secondary Outcome Measures:
  • Change From Baseline in Serum LDL-cholesterol at 8 Weeks [ Time Frame: Every 8 weeks ]
    Change in serum LDL-cholesterol was calculated as LDL-cholesterol at 8 weeks minus LDL-cholesterol at baseline. Over-night fasting serum LDL-cholesterol was measured with an enzymatic method.

  • Body Weight at 8 Weeks [ Time Frame: Every 8 weeks ]
    Body weight was measured by trained staff using a standard protocol at week 8.


Enrollment: 352
Study Start Date: July 2002
Study Completion Date: April 2008
Primary Completion Date: April 2008 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Soy protein-milk protein-carbohydrate
Participants received 40 grams of soy protein daily for 8 weeks, 40 grams of milk protein daily for 8 weeks, and 40 grams of carbohydrate daily for 8 weeks.
Dietary Supplement: Soy protein-milk protein-carbohydrate
40 grams of soy protein per day for 8 weeks, 40 grams of milk protein per day for 8 weeks, and 40 grams of carbohydrate per day for 8 weeks
Experimental: Milk protein-carbohydrate-soy protein
Participants received 40 grams of milk protein daily for 8 weeks, 40 grams of carbohydrate daily for 8 weeks, and 40 grams of soy protein daily for 8 weeks.
Dietary Supplement: Milk protein-carbohydrate-soy protein
40 grams of milk protein per day for 8 weeks, 40 grams of carbohydrate per day for 8 weeks, 40 grams of soy protein per day for 8 weeks.
Placebo Comparator: Carbohydrate-soy protein-milk protein
Participants received 40 grams of complex carbohydrate daily for 8 weeks, 40 grams of soy protein daily for 8 weeks, and 40 grams of milk protein daily for 8 weeks.
Behavioral: Carbohydrate-soy protein-milk protein
40 grams of carbohydrate per day for 8 weeks, 40 grams of soy protein per day for 8 weeks, 40 grams of milk protein per day for 8 weeks,

Detailed Description:

BACKGROUND:

At least 50 million adult Americans have high BP, which is one of the most important modifiable risk factors for coronary heart disease, stroke, and end-stage kidney disease. Nutrient intake has been related to the development of high BP, and nutritional modifications have become an important approach for the treatment and prevention of high BP. While the effect of sodium, potassium, and alcohol on BP has been studied extensively, the effect of dietary macronutrients, such as protein, has not been as well studied. Results from this study may provide justification for recommending protein supplements for the prevention and treatment of high BP in the general population.

DESIGN NARRATIVE:

The study will enroll 280 healthy participants with BP levels higher than optimal or with stage-1 hypertension (systolic BP of 120-159 mm Hg and diastolic BP of 80-95 mm HG). Participants will be recruited by a mass mailing and a worksite/community-based BP screening in New Orleans, Louisiana, and Jackson, Mississippi. Following a two-week screening period, eligible participants will receive either 40 grams of soy protein, 40 grams of milk protein, or 40 grams of complex carbohydrates (control) daily for eight weeks. Following those eight weeks, participants will not receive any supplements for three weeks. Participants will then repeat the process with the other two supplements. The primary outcome will be difference in BP during the soy protein supplementation, milk protein supplementation, and placebo control phases. In addition, changes in serum lipids; waist and hip circumference; and fasting plasma insulin, glucose, leptin, and homocysteine will be monitored and examined in terms of impact on BP level.

  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   22 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Systolic BP of 120 to 159 mm Hg and diastolic BP of 80 to 95 mm Hg (average of 6 measurements at 2 screening visits)
  • Willing to participate in all aspects of the study

Exclusion Criteria:

  • Consumption of dietary protein greater than or equal to 1.63 grams/kg per day, as determined by two 24-hour dietary recalls
  • Stage-2 or higher severe hypertension (systolic BP greater than or equal to 160 mm Hg and/or diastolic BP greater than or equal to 95 mm Hg)
  • Use of antihypertensive medications or medications that affect BP
  • History of clinical heart disease (e.g., angina/heart attack, coronary revascularization, heart failure, stroke/transient ischemic attack, peripheral arterial disease)
  • Kidney disease (serum creatinine level greater than or equal to 1.7 mg/dL for men and greater than or equal to 1.5 mg/dL for women)
  • Current hypercholesterolemia (fasting serum total cholesterol greater than or equal to 240 mg/dL) or use of cholesterol-lowering medications
  • Current diabetes (fasting serum glucose greater than or equal to 126 mg/dL) or use of insulin or oral hypoglycemic agents
  • Severe obesity (body mass index greater than or equal to 40 kg/m²)
  • Current use of prescription weight loss medications, underwent weight loss surgery, and/or experienced weight loss greater than 15 pounds within the 6 months prior to study entry
  • Cancer (except non-melanoma skin cancer) that required treatment during the year prior to study entry
  • Consumption of more than 14 alcoholic beverages per week
  • Current participation in another medical study
  • Consumption of milk or soy protein greater than or equal to the 90th percentile of intake in the U.S. general population
  • Has another member of the household participating in the study
  • Study employees or living with study employees
  • Allergy or intolerance to soy protein or milk protein products
  • Allergy to aspartame
  • Plans to move out of the study area (greater than or equal to 50 miles from the study site) and has difficulty coming to the study site
  • Inability or unwillingness to cooperate during the screening visits
  • Poor compliance during the screening period (intake of less than 85% of supplements)
  • Pregnant or plans to become pregnant during the study
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00046566


Locations
United States, Louisiana
Tulane University
New Orleans, Louisiana, United States, 70112
Sponsors and Collaborators
Tulane University
National Heart, Lung, and Blood Institute (NHLBI)
Investigators
Study Chair: Jiang He, MD Tulane University
  More Information

Additional Information:
Publications:
Responsible Party: Jiang He, MD, PhD, Professor and Chair, Tulane University
ClinicalTrials.gov Identifier: NCT00046566     History of Changes
Other Study ID Numbers: 145
R01HL068057 ( U.S. NIH Grant/Contract )
First Submitted: September 30, 2002
First Posted: October 1, 2002
Results First Submitted: November 30, 2016
Results First Posted: July 24, 2017
Last Update Posted: July 24, 2017
Last Verified: April 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Additional relevant MeSH terms:
Cardiovascular Diseases
Heart Diseases