Soy Isoflavone Reduces Menopausal Symptoms

Postmenopausal women who take a daily supplement containing soy isoflavones may experience fewer symptoms associated with menopause, according to a new study in Obstetrics and Gynecology.¹ Isoflavones are a group of compounds found in certain beans and grains that have mild estrogen-like activity (thus, are commonly referred to as “phytoestrogens”). Research suggests that the soy’s phytoestrogenic activity is due to two isoflavones in particular, daidzein and genistein.²

This four-month controlled trial examined 80 postmenopausal women between 45 and 55 years old, who were assigned to receive either 100 mg of soy isoflavones per day or placebo. Frequency and severity of 11 different menopausal symptoms were measured by questionnaire before and after treatment. Blood cholesterol and sugar levels, blood pressure, body mass index (BMI; a measure of obesity) and reproductive hormones were measured at the same intervals.

The results showed a significant decrease in menopausal symptoms from the beginning to the end of the study in women taking soy isoflavones. In addition, menopausal symptom scores in women taking soy isoflavones were 40% lower (indicating less severe symptoms) than in those taking a placebo, a statistically significant difference. No significant differences were found in blood sugar, blood pressure, or BMI between the two groups of women. In women taking soy isoflavones, blood levels of estradiol (a type of estrogen) doubled, whereas estradiol levels did not change in women taking the placebo. However, as isoflavone treatment did not increase the thickness of the uterine lining, this treatment does not appear to increase the risk of uterine cancer.

Compared with the placebo group, the soy group had a significant reduction in total cholesterol and LDL (“bad”) cholesterol, suggesting that soy has heart-health benefits as well. Other studies have demonstrated that daily consumption of soy decreases the risk of developing cardiovascular disease, including stroke and heart attack.³ However, it is not clear whether the cardiovascular benefits of soy are due to the isoflavones or to other components of soy.

Symptoms of menopause may include hot flashes, insomnia, nervousness, joint pain, headache, or heart palpitations. Estrogen replacement therapy (ERT) is used conventionally to treat these symptoms, but may increase the risk of developing uterine and breast cancer. The authors of the new study suggest that taking a daily supplement of soy isoflavones may be a safe and effective treatment to control the symptoms of menopause, without increasing cancer risk.

References:

1. Han KK, Soares JM Jr, Haidar MA, et al. Benefits of Soy Isoflavone Therapeutic Regimen on Menopausal Symptoms. Obstet Gynecol 2002;99:389–94.
2. Wei H, Brown R, Cai Q, et al. Antioxidant and antipromotional effects of the soybean isoflavone genistein. Proc Soc Exp Biol Med 1995;208:124–9.
3. Sirtori CR. Risks and benefits of soy phytoestrogens in cardiovascular diseases, cancer, climacteric symptoms and osteoporosis. Drug Saf 2001;24:665–82.

Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of Garlic and Cholesterol: Everything You Need to Know (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice in Westport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.

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