Effect of Soybean Protein on Blood Pressure: A Randomized, Controlled Trial

5 July 2005 | Volume 143 Issue 1 | Pages 1-9

Background: Epidemiologic studies suggest that vegetable protein intake is inversely related to blood pressure.

Objective: 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.

Setting: Three communities in the People's Republic of China.

Patients: 302 participants 35 to 64 years of age with an initial untreated systolic blood pressure of 130 to 159 mm Hg, diastolic blood pressure of 80 to 99 mm Hg, or both.

Intervention: Study participants were randomly assigned to receive 40 g of isolated soybean protein supplements per day or complex carbohydrate control for 12 weeks; 91.4% completed the intervention.

Measurements: Blood pressure measurements were obtained by using random-zero sphygmomanometers at baseline and at 6 and 12 weeks.

Results: At baseline, the mean systolic and diastolic blood pressures were 135.0 mm Hg (SD 10.9) and 84.7 mm Hg (SD 6.9), respectively. Compared with the control group, the net changes in systolic blood pressure and diastolic blood pressure were –4.31 mm Hg (95% CI, –2.11 to –6.51 mm Hg; P < 0.001) and –2.76 mm Hg (CI, –1.35 to –4.16 mm Hg; P < 0.001), respectively, after the 12-week intervention. The net changes in systolic and diastolic blood pressure reductions were –7.88 mm Hg (CI, –4.66 to –11.1 mm Hg) and –5.27 mm Hg (CI, –3.05 to –7.49 mm Hg), respectively, in persons with hypertension and –2.34 mm Hg (CI, 0.48 to –5.17 mm Hg) and –1.28 mm Hg (CI, 0.52 to –3.07 mm Hg), respectively, in those without hypertension.

Limitations: This trial did not examine whether the blood pressure reduction was due to protein or isoflavones in soybean.

Conclusions: Soybean protein supplementation resulted in a reduction in systolic and diastolic blood pressure. These findings suggest that increased intake of soybean protein may play an important role in preventing and treating hypertension.

Editors' Notes Context Observational studies suggest that higher intake of vegetable protein is associated with lower blood pressures. Contribution This double-blind trial from China randomly assigned 302 adults with high-normal or mildly elevated blood pressures (diastolic blood pressure of 80 to 99 mm Hg, systolic blood pressure of 130 to 159 mm Hg, or both) to daily cookies containing 40 g of either soybean protein or complex carbohydrates. At 12 weeks, soybean cookies reduced diastolic and systolic blood pressure values by about 3 to 4 mm Hg more than did the carbohydrate cookies. Cautions The follow-up duration was short. Implications Soybean protein supplementation might help lower blood pressure in some people. –The Editors

 

Author and Article Information

From Tulane University, New Orleans, Louisiana; and Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, People's Republic of China.

This trial is registered as NCT00107744 on http://clinicaltrials.gov.

Note: Drs. He and Gu contributed equally to this work.

Grant Support: By a Career Development Award from the Tulane University Health Sciences Center (Dr. He); grant R01 HL68057 from the National Heart, Lung, and Blood Institute of the National Institutes of Health (Dr. He); and grant 96-906-02-02 of the National Ninth Five-Year Plan Key Program from the Ministry of Science and Technology of the People's Republic of China (Dr. Gu).

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Jiang He, MD, PhD, Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, 1430 Tulane Avenue SL 18, New Orleans, LA 70112-2699; e-mail, jhe{at}tulane.edu.

Current Author Addresses: Dr. He: Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, 1430 Tulane Avenue, SL 18, New Orleans, LA 70112-2699.

Drs. Gu, Wu, and Duan and Ms. Chen: Cardiovascular Institute and Fuwai Hospital, 167 Beilishi Road, Beijing, 100037 People's Republic of China.

Dr. Chen: Department of Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112.

Dr. Whelton: Office of Senior Vice President for Health Sciences, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112.

Author Contributions: Conception and design: J. He, D. Gu, X. Wu, Jing Chen, P.K. Whelton.

Analysis and interpretation of the data: J. He.

Drafting of the article: J. He.

Critical revision of the article for important intellectual content: J. He, D. Gu, X. Wu, Jing Chen, P.K. Whelton.

Final approval of the article: J. He, D. Gu, X. Wu, Jichun Chen, X. Duan, Jing Chen, P.K. Whelton.

Provision of study materials or patients: J. He, D. Gu, X. Wu, Jichun Chen, X. Duan.

Statistical expertise: J. He.

Obtaining of funding: J. He, D. Gu.

Administrative, technical, or logistic support: J. He.

Collection and assembly of data: J. He, D. Gu, X. Wu, Jichun Chen, X. Duan.

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Letter to Editor

Balavenkatesh Kanna, et al.

Annals Online, 25 Jul 2005 [Full text]