Add Soy to Your Heart-Healthy Diet

Healthnotes Newswire (July 5, 2007)—Women with high blood pressure (hypertension) were able to lower their blood pressure and cholesterol but substituting soy nuts for nonsoy protein in a heart-healthy diet, a new study has found.

“Coronary heart disease is the most common and lethal outcome of hypertension,” said Francine K. Welty, MD, PhD, the study’s lead author and an associate professor at Beth Israel Deaconess Medical Center in Boston, a teaching affiliate of Harvard Medical School. The study looked at the effect of soy nuts (dry-roasted soybeans) on blood pressure when added to the Therapeutic Lifestyle Changes (TLC) diet. The National Cholesterol Education Program recommends the TLC diet as a way to lower coronary heart disease risk.

In the TLC diet, a maximum of 30% of calories come from fat (12% monounsaturated fat, 11% polyunsaturated fat, and less than 7% saturated fat), 15% from protein, and 55% from carbohydrate; the diet also restricts cholesterol to less than 200 mg per day and requires 1,200 mg of calcium and two fatty fish meals per week.

In this controlled clinical trial, 60 postmenopausal women were tested for the effect of one-half cup of soy nuts daily for eight weeks on blood pressure and cholesterol levels. Women with chronic high blood pressure were counseled to eat less than 2 grams of sodium per day. Women getting less than ideal amounts of calcium from their diet were given calcium supplements. After a four-week diet-only phase, the women were randomly assigned to one of two groups for eight weeks, then switched over to the other. One group ate one-half cup of unsalted soy nuts containing 25 grams of soy protein and 101 mg of soy isoflavones per day; the other group ate no soy.

Eating soy nuts significantly reduced both systolic and diastolic blood pressure measurements in all 12 hypertensive women and in 40 of the 48 women with normal blood pressure. (Systolic blood pressure refers to the upper number, which measures the pressure in the arteries when the heart is contracting; the diastolic number is the lower number, which measures the arterial pressure between heart contractions.)

This is the first study to directly compare the blood pressure–lowering effect of a whole soy food in people with normal and elevated blood pressure. Hypertensive women had a 10% lower systolic blood pressure and a 7% lower diastolic blood pressure; these reductions were twice as great as the reductions observed in women with normal blood pressure.

“These results are comparable with those seen with antihypertensive drugs,” Dr. Welty concluded. “If the findings are repeated in a larger group they may have important implications for reducing cardiovascular risk in postmenopausal women.”

(Arch Intern Med 2007;167:1060–7)

Jeremy Appleton, ND, CNS, is a licensed naturopathic physician, certified nutrition specialist, and published author. Dr. Appleton was the Nutrition Department Chair at the National College of Naturopathic Medicine, has served on the faculty at Bastyr University of Natural Health Sciences, and is a former Healthnotes Senior Science Editor and a founding contributor to Healthnotes Newswire. He has worked extensively in scientific and regulatory affairs in the supplement industry and is now a consultant through his company Praxis Natural Products Consulting and Wellness Services.

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