Soy after Menopause: More than Hot Flash Relief

27 March 2008

Many postmenopausal women consume soy hoping that it might reduce their hot flashes and other symptoms. A new study suggests that adding soy isoflavones to the diet can also produce a healthier distribution of body fat─namely, less fat in the abdomen─which could lead to a number of other health benefits.

The study, published in Fertility and Sterility, included 15 postmenopausal women whose last menstrual period was between one and five years before entering the study. They received either a daily soy shake providing 20 grams of protein and 160 mg of isoflavones or a daily milk-based shake with the same amount of protein and calories. After three months, the abdominal fat in the women taking the soy shake had decreased, but had increased in the women taking the milk-based shake.

For better heart health, say goodbye to the jelly belly

While the total amount of body fat is an important indicator of cardiovascular risk, the way the fat is distributed makes a marked difference. When extra body fat accumulates in the abdomen, a pattern sometimes referred to as the “apple shape,” the implications are much more serious than when it is stored in the hips and thighs, or the “pear-shape.” The apple shape has been linked to increased risk of type 2 diabetes, breast and endometrial cancers, high blood pressure, stroke, and coronary artery disease.

Women producing estrogen have a tendency to develop more of a pear shape, but after menopause, when levels are lower, fat distribution often shifts toward the abdomen. Insulin has the opposite effect: more fat is deposited in the abdomen when insulin levels are high, such as occurs in insulin resistance and type 2 diabetes.

Shake it up with soy

In this study, drinking a daily soy shake with protein and isoflavones reduced abdominal fat, suggesting one possible way that soy might exert health benefits seen in other studies. Dr. Cindy Sites of the University of Alabama at Birmingham, the lead author of the study, said that using the soy shake made it easy for the women to get a high level of soy isoflavones. “Some of the women used the soy shakes mixed with their breakfast cereal, and others tried mixing it with fruit in the blender to make smoothies,” she said.

Getting this daily amount of isoflavones using other soy foods might be more difficult. The equivalents:

• 1 cup of green soybeans, also called edamame

• 1/2 cup of roasted soybeans

• 8 cups soymilk

• 1 pound of tofu, a pound would be needed.

Can eating ordinary amounts of soy foods affect abdominal fat? “Since we only tested the soy shake with a high amount of isoflavones, we don't know what impact, if any, smaller amounts may have,” Sites answered.

Avoid the apple shape

The best way for postmenopausal women to avoid becoming more apple-shaped is to eat a well-rounded diet that is low in refined carbohydrates (like white flour) and added sugars (including high-fructose corn syrup), and high in:

• whole fruits (not juices) and vegetables

• whole grains

• healthy fats like olive oil, nuts, and seeds

• protein from beans and lentils, fish, and lean poultry and meat

Based on the findings of this study, adding a soy shake might also be a good idea.

(Fertil Steril 2007;88:1609¬-17)

Maureen Williams, ND, received her bachelor's degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.