Soy nuts may cut womens blood pressure
blood pressure in postmenopausal women by up to 10 per cent, says a
new study from the US.
The results, published in the Archives of Internal Medicine, also reports that regular consumption of soy nuts led to reductions in cholesterol levels, and may offer a "practical, safe and inexpensive modality to reduce blood pressure," said the researchers. "In this eight-week crossover trial, soy nuts containing 25 g of soy protein and 101 mg of aglycone isoflavones lowered blood pressure in hypertensive and normotensive postmenopausal women compared with the Therapeutic Lifestyle Changes (TLC) diet without soy," wrote lead author Francine Welty, from the Beth Israel Deaconess Medical Center, Boston. "To our knowledge, this is the first study to directly compare the effects of a whole soy food in normotensive and hypertensive individuals," she added. In the UK alone, there are an estimated 10m people with hypertension, defined as having blood pressure higher than 140/90 mmHg. The condition is a major risk factor for cardiovascular disease (CVD), which causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy an estimated €169bn ($202bn) per year. The new study recruited 60 healthy post-menopausal women (average age 56, average BMI 26.7 kg per sq m) who ate two diets for eight weeks - each in random order. The first diet, the TLC diet, consisted of 30 per cent of calories from fat (with 7 per cent or less from saturated fat), 15 per cent from protein and 55 per cent from carbohydrates; 1,200 milligrams of calcium per day; two meals of fatty fish (such as salmon or tuna) per week; and less than 200 milligrams of cholesterol per day. The second diet had the same calorie, fat and protein content, but the 25 grams of protein were replaced with one-half cup of unsalted soy nuts. The researchers took blood samples and pressure measurements at the beginning and end of each eight-week period. At the beginning of the study, 12 women were classed as hypertensive, with the remaining 48 being normotensive. "Soy nut supplementation significantly reduced systolic [top number] and diastolic [bottom number] blood pressure in all 12 hypertensive women and in 40 of the 48 normotensive women," report the authors. Indeed, hypertensive women consuming the soy nuts as part of the TLC diet experienced systolic and diastolic blood pressure reductions of 9.9 per cent and 6.8 per cent, respectively, while normotensive women experienced reductions and 5.2 per cent and 2.9 per cent, respectively. "A 12-millimetre of mercury decrease in systolic blood pressure for 10 years has been estimated to prevent one death for every 11 patients with stage one hypertension treated; therefore, the average reduction of 15 milligrams of mercury in systolic blood pressure in hypertensive women in the present study could have significant implications for reducing cardiovascular risk and death on a population basis," wrote Welty. In addition to blood pressure reductions, the women with high blood pressure at the start of the study also experienced beneficial changes in levels of low-density lipoprotein (LDL - "bad") cholesterol and apoliprotein B (a particle that carries LDL cholesterol), with reductions reported of 11 and eight per cent, respectively. "Levels of triglyceride were seven per cent and 11 per cent lower in normotensive and hypertensive women, respectively, in the soy diet arm compared with the control arm," wrote Welty. "Although these reductions were not statistically significant, their magnitude is similar to reductions in triglyceride levels observed in other soy studies and may have clinical relevance, especially since triglyceride levels are stronger predictors of cardiovascular risk in women than in men." The researchers suggest that the isoflavone content of the soy nuts may be responsible for the beneficial changes to blood pressure, but also not that when provided in isolation in the form of supplements, similar benefits were not observed in other studies, suggesting that isoflavones may work synergistically. "This study was performed in the free-living state; therefore, dietary soy may be a practical, safe and inexpensive modality to reduce blood pressure. If the findings are repeated in a larger group they may have important implications for reducing cardiovascular risk in postmenopausal women on a population basis," concluded the researchers. Source: Archives of Internal Medicine Volume 167, Pages 1060-1067 "Effect of Soy Nuts on Blood Pressure and Lipid Levels in Hypertensive, Prehypertensive, and Normotensive Postmenopausal Women" Authors: F.K. Welty, K.S. Lee, N.S. Lew, J.-R. Zhou