Soy Isoflavones & Hot Flashes

Hot flashes are one the most common symptoms of menopause, with three out of four menopausal women experiencing them. Traditionally, hot flashes have been treated with synthetic estrogen in the form of hormone replacement therapy, or HRT. More women are looking for natural alternatives to HRT because of the downsides of synthetic hormones. Research published in the October 2010 issue of the Journal of the American Medical Association found an increase in breast cancer in postmenopausal women who take the synthetic estrogen and progesterone contained in HRT. Soy isoflavones, found in the soy foods we eat, are believed to provide the same benefits as the estrogen that is naturally produced in the body.

Hot Flashes

The cause of hot flashes is still unknown, according to the North American Menopause Society. The sharp decrease in estrogen concurrent with menopause is believed to initiate a chain of reactions that begins in your hypothalamus, the part of the brain that controls body temperature. The hypothalamus reacts as if your body is too warm and triggers dilation of blood vessels near the surface of the skin. This dilation shows up as a flushed feeling or a hot flash.

Soy Isoflavones

Soy Isoflavones are chemical compounds called flavonoids that are found in soybeans. They are also called phytoestrogens, meaning plant-derived compounds with estrogen effects. When ingested, they function as weak-estrogens by binding to estrogen receptors. Your body has cells with estrogen receptors located in the reproductive organs, brain, liver and fat cells.

The three most common types of isoflavones in soybeans are called genistein, daidzein and glycitein. The chemical structure of these compounds is similar to estrogen, but they are not estrogen molecules. However, they are close enough that they will bind with estrogen-sensitive cells. This will give you the benefits of estrogen at a much lower potency and without the drawbacks of the synthetic hormones found in HRT.

Sources

Isoflavones are found in varying amounts in soybeans and soybean products. According to the U.S. Department of Agriculture-Iowa State University Database, soy flour is rich in isoflavones, with 177.89 mg per 100 g. Soy protein isolate is extracted from soybeans and contains 97.43 mg isoflavones per 100 g. Raw soybeans vary in the amount of isoflavones based on the type of soybean. Taiwan soybeans have 59.75 mg isoflavones per 100 g; Korean soybeans have 144.99 mg per 100 g and Japanese soybeans have 118 mg per 100 g.

Other soy products containing isoflavones are tofu, tempeh, miso, soy cheeses and soy yogurt.

Research

Some women experience an improvement in the number and intensity of hot flashes after adding soy isoflavones to their diets. According to the February 2006 issue of the American Family Physician, soy isoflavones reduced hot flashes by 9 percent to 40 percent in some trials. However, not all women receive the same results. In Japan, a study of 1,106 women ages 35 to 54 with menopausal hot flashes found that soy isoflavones in the diet had a protective effect against hot flashes. The study was published in the American Journal of Epidemiology.

Considerations

Always seek advice from a medical doctor before proceeding with soy isoflavone supplements and foods. Although menopause is a natural transition in life, talk with your health care professional about your specific conditions. Some women may have allergies to soy and should be evaluated by a medical professional.