Studies suggest that soy protein helps to lower blood cholesterol, and in 1999, the Food and Drug Administration approved a health claim for soyfoods and heart disease based on this effect. Soyfoods are also low in saturated fat making them a good choice in heart healthy diets. But elevated cholesterol is just one of several risk factors for coronary heart disease. An equally if not more important one is elevated blood pressure. Elevated blood pressure affects about 74 million Americans or about one in three adults, and the drugs available to treat this condition aren’t nearly as effective as the drugs used to treat elevated cholesterol.
Two groups of researchers recently conducted evaluations of studies on the effects of soyfoods on blood pressure. They each conducted a meta-analysis, a commonly used statistical approach that combines a large number of studies for the purpose of integrating the findings. In the first analysis, Chinese researchers analyzed the results from 11 studies and found that soy lowered systolic blood pressure by 2.5 points and diastolic blood pressure by 1.5 points. The second analysis included 27 different studies and showed similar results. Soy lowered systolic and diastolic blood pressure by 2.2 and 1.4 points, respectively. Although these reductions may seem small, they are meaningful. It is estimated that decreases of this magnitude can lower risk of stroke, coronary heart disease and mortality by 10, 5, and 4%, respectively. When combined with the other coronary benefits of soyfoods, it is clear that adding soyfoods to your diet is a good way to protect yourself against cardiovascular disease.
Liu XX, Li SH, Chen JZ, Sun K, Wang XJ, Wang XG, Hui RT. Effect of soy isoflavones on blood pressure: A meta-analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis. 2011.
Dong JY, Tong X, Wu ZW, Xun PC, He K, Qin LQ. Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials. Br. J. Nutr. 2011, 1-10.