Clinical Trial of Dietary Protein and Blood Pressure (ProBP)
|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 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)
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|
- 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.
- 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.
|Study Start Date:||July 2002|
|Study Completion Date:||April 2008|
|Primary Completion Date:||April 2008 (Final data collection date for primary outcome measure)|
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,
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.
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.
Please refer to this study by its ClinicalTrials.gov identifier: NCT00046566
|United States, Louisiana|
|New Orleans, Louisiana, United States, 70112|
|Study Chair:||Jiang He, MD||Tulane University|