Study Shows Health Effects of Soy

June 30, 1999

Menopausal women who added soy protein to their daily diets had less intense hot flashes and night sweats and also had improvements in cholesterol and blood pressure levels, report researchers from Wake Forest University Baptist Medical Center in the journal Menopause.

The study of 51 middle-aged women showed that a twice-daily dose of powdered soy protein lowered total cholesterol by an average of 6 percent, which translates into a 12 percent reduction in heart disease risk. Diastolic blood pressure (pressure between heart beats), dropped by an average of 5 points. Research has shown that a 5-point prolonged decrease in blood pressure is associated with 21 percent less heart disease and 34 percent fewer strokes.

The women tried three different levels of soy, each for six weeks,: 10 grams of soy protein twice a day, 20 grams of protein once a day and a carbohydrate supplement containing no soy. They mixed the soy powder in milk or juice or added it to cereal or other foods. Consuming the soy protein once a day was just as effective at reducing cholesterol as taking it in two doses. But the twice-a-day diet was more effective at reducing blood pressure and the severity of menopause symptoms.

Soy protein, found in tofu and other foods made from soy beans, has been linked to a variety of health benefits. Women who live in Japan and other countries where substantial amounts of soy are consumed have fewer adverse menopausal symptoms as well as lower rates of heart disease and breast cancer.

Researchers believe that the benefits of soy come from isoflavones, plant chemicals that act similarly to the hormone estrogen in the body. The women in the study consumed about 34 milligrams of isoflavones, levels found in 1/8 cup of soy nuts, ½ cup of low-fat tofu and one cup of regular soy milk.

The Medical Center will soon begin recruitment for a study to compare doses of 50 and 90 milligrams of isoflavones, the amounts consumed by most Japanese women.

"Our goal is to see whether these higher doses will not just reduce symptoms, but will eliminate them," said Gregory Burke, M.D., M.S., co-leader of the study. "We want to find alternatives to hormone replacement therapy to treat the symptoms of menopause."

Hormone replacement therapy has been shown to successfully treat menopausal symptoms and reduce the risk of osteoporosis, but less than 15 percent of menopausal women take it.


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