Clinical Trial of Protein and Blood Pressure
Clinical Trial of Protein and Blood Pressure
The purpose of this randomized, double-blind, controlled trial is to examine the effect of
 soybean protein supplementation on blood pressure in persons with prehypertension or stage-1
 hypertension.
Background: Epidemiologic studies suggest that vegetable protein intake is inversely related
 to blood pressure.

 Objectives: To examine the effect of soybean protein supplementation on blood pressure in
 persons with prehypertension or stage-1 hypertension

 Design: Randomized, double-blind, controlled trial

 Study Participants: 350 participants, aged 35-64 years, with an initial untreated systolic
 blood pressure of 130-159 mmHg and/or diastolic blood pressure of 80-99 mmHg

 Intervention: Study participants will be randomly assigned to take 40-grams of isolated
 soybean protein supplements per day or complex carbohydrate control for 12 weeks.

 Outcomes: Blood pressure measurements will be obtained using random-zero sphygmomanometers at
 baseline and during the trial at weeks 6 and 12. Net changes in systolic and diastolic blood
 pressure before and after the intervention is the primary outcome.
Inclusion Criteria:

 1. 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)

 2. Willing to participate in all aspects of the study

 Exclusion Criteria:

 1. Consumption of dietary protein greater than or equal to 1.63 grams/kg per day, as
 determined by two 24-hour dietary recalls

 2. 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)

 3. Use of antihypertensive medications or medications that affect BP

 4. History of clinical heart disease (e.g., angina/heart attack, coronary
 revascularization, heart failure, stroke/transient ischemic attack, peripheral
 arterial disease)

 5. 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)

 6. Current hypercholesterolemia (fasting serum total cholesterol greater than or equal to
 240 mg/dL) or use of cholesterol-lowering medications

 7. Current diabetes (fasting serum glucose greater than or equal to 126 mg/dL) or use of
 insulin or oral hypoglycemic agents

 8. Severe obesity (body mass index greater than or equal to 40 kg/m²)

 9. 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

 10. Cancer (except non-melanoma skin cancer) that required treatment during the year prior
 to study entry

 11. Consumption of more than 14 alcoholic beverages per week

 12. Current participation in another medical study

 13. Consumption of milk or soy protein greater than or equal to the 90th percentile of
 intake in the U.S. general population

 14. Has another member of the household participating in the study

 15. Study employees or living with study employees

 16. Allergy or intolerance to soy protein or milk protein products

 17. Allergy to aspartame

 18. 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

 19. Inability or unwillingness to cooperate during the screening visits

 20. Poor compliance during the screening period (intake of less than 85% of supplements)

 21. Pregnant or plans to become pregnant during the study