Should You Use Soybean Protein to Lower Your Patients’ Blood Pressure?
Should You Use Soybean Protein to Lower Your Patients’ Blood Pressure?
Abstract & Commentary
By Ralph R. Hall, MD, FACP, Emeritus Professor of Medicine University of Missouri- Kansas City School of Medicine. Dr. Hall is a consultant for Aventis.
Synopsis: Soybean cookies reduced diastolic and systolic blood pressure by 3 to 4 mg Hg more than did carbohydrate cookies.
Source: He J, et al. Effect of soybean protein on blood pressure: a randomized, controlled trial. Ann Intern Med. 2005;143:1-9.
This study was done because epidemiologic studies sug-gest vegetable protein intake is inversely related to blood pressure. It was carried out in 3 communities of the People’s Republic of China. There were 362 participants 35-64 years of age with an initial untreated systolic blood pressure of 130 to 159 mm Hg, and a diastolic blood pressure of 80 to 99 mm Hg, or both.
Subjects were randomly assigned to receive 40 g per day of isolated soybean protein as cookies, per day, or a complex carbohydrate control for 12 weeks; 91.4 % completed the intervention. The participants and researchers did not know who received each type of cookie.
Blood pressures were obtained at baseline and at 6 and 12 weeks. At baseline the mean systolic and diastolic 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 and diastolic blood pressure were -4.31 mm Hg and -2.76 mm Hg respectively, after the 12-week intervention. The net change in systolic blood pressure was -7.88 mm Hg and -2.34 mm Hg in the soy protein group. The changes were greater in those with hypertension than in those without hypertension.
One of the limitations noted was whether the blood pressure reduction was due to the protein or the isoflavones in the soybean.
The conclusions were that soybean supplementation resulted in a reduction in systolic and diastolic blood pressure and that these findings suggest that increased intake of soybean protein may play a role in preventing and treating hypertension.
Commentary
There is evidence that a plant-based diet, which contains much less soy protein than in this study, will reduce blood pressure, is associated with a decrease in the risk of cancer and will reduce low-density cholesterol.1
It should be noted that the DASH Diet2 reduced the blood pressure even more than this high soy diet.
A recent successful study of plant-based diets to reduce low density cholesterol contained only 19 grams of soy protein per day compared to the 40 grams that was contained in the soy cookie diet.1 This may be very important in that the 2 studies in China cited by He et al note a 2-fold increase in the risk of bladder cancer in persons with a high intake of soy. (The intake of soy protein in the high cancer group in the 2 Chinese studies averaged nearly 90 grams per day of soy protein.) In addition, many would find it difficult to maintain a soy protein intake of 40 grams a day in ordinary food from their local food supply.
Combining food groups that lower both cholesterol and blood pressure, and which avoid excesses of any one product or food group seems a more prudent approach to diet than a diet containing large amounts of soy. The Mediterranean diet which has been shown to reduce the incidence of cancer, heart disease and which reduces mortality,3 and the Dash Diet are proven, safe, and practical approaches to a healthy diet.
References
1. Gardner CD, et al. The effect of a plant-based diet on plasma lipids in hypercholesterolemic adults: a randomized trial. Ann Intern Med. 2005;142:725-733.
2. Sacks FM, et al. Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group. N Engl J Med. 2001;344:3-10.
3. Knoops KT, et al. Mediterranean diet, lifestyle factors, and 10-year mortality in elderly European men and women: the HALE project. JAMA. 2004;292:1433-1439.
Soybean cookies reduced diastolic and systolic blood pressure by 3 to 4 mg Hg more than did carbohydrate cookies.Subscribe Now for Access
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