Effect of Soy Intake on Blood Pressure and Lipids

In hypertensive women who added soy to their diets, blood pressure decreased.

Dietary soy is one of several factors that might explain the lower incidence of coronary heart disease in Asian countries than in Western countries. In a randomized, crossover trial, 60 healthy postmenopausal women followed the National Cholesterol Education Program (NCEP) diet or the NCEP diet with 25 g of soy protein supplied as one half cup of unsalted soy nuts (i.e., roasted soy beans) daily while maintaining an equivalent total protein content. Each phase was continued for 8 weeks, and researchers assessed the effect of the diets upon lipids and blood pressure (BP). Patients with systolic BP 165 mm Hg or diastolic BP of 100 mm Hg were excluded from the trial.

Mean BP was lower with soy than without, both among hypertensive women (137/82 vs. 152/88 mm Hg) and normotensive women (110/67 vs. 116/69 mm Hg). The soy diet was significantly lower in total and saturated fat than the control diet. Nonetheless, among normotensive women, total, LDL, and HDL cholesterol levels did not differ across diets. Among hypertensive women, LDL decreased by 11%; total and HDL cholesterol levels did not differ significantly.

Comment: In this small randomized crossover trial, adding soy protein to a diet showed impressive reductions in blood pressure; the magnitude of this effect was surprising and certainly requires confirmation. In contrast, the effect upon lipids was limited.

— Jamaluddin Moloo, MD, MPH

Published in Journal Watch General Medicine June 14, 2007

Citation(s):
Welty FK et al. Effect of soy nuts on blood pressure and lipid levels in hypertensive, prehypertensive, and normotensive postmenopausal women. Arch Intern Med 2007 May 28; 167:1060-7.