(October 2, 2003)—Postmenopausal women who take supplements containing soy isoflavones may experience improved memory and recall ability, according to a study in Pharmacology, Biochemistry and Behavior (2003;75:721–9). This study adds to the growing body of evidence that suggests soy isoflavones may help reverse the cognitive decline associated with menopause.
In the new study, 33 postmenopausal women between the ages of 50 and 65 years who were not taking conventional hormone replacement therapy (HRT) were randomly assigned to receive 60 mg of soy isoflavones per day or a placebo for 12 weeks. None of the participants consumed soy products as part of their diets. A battery of tests that measure cognition and menopausal symptom questionnaires were given initially and at the conclusion of the study.
Women taking soy isoflavones had significant improvements in recall, logical thinking, planning tasks, and attention compared with women taking a placebo, which translates to better memory and ability to focus on a particular task. No improvement in menopausal symptoms (such as hot flashes, night sweats, insomnia, and heart palpitations) or mood was observed in either the treatment or placebo group; however, there was a low prevalence of menopausal symptoms in both groups at the beginning of the study.
Studies suggest that two key isoflavones found in soy called daidzein and genistein may be responsible for the benefits of soy in postmenopausal women. These compounds have been shown to mimic the effects of estrogen in the brain, which may explain the effects on memory and concentration. Most of the research on soy isoflavones has focused specifically on treating hot flashes, although a few small preliminary studies have also found improvements in cognition. Other studies have used soy protein to treat menopausal symptoms, but there is not enough evidence to determine whether soy protein produces similar improvements in cognition as pure soy isoflavones.
Recent studies with conventional HRT have suggested that long-term use may lead to breast cancer, uterine cancer, and heart disease. These risks of HRT have led many physicians and postmenopausal women to look for safer treatments. No serious adverse effects have been reported in humans with consumption of soy isoflavones. The dose of soy isoflavones used in this study was relatively low and some women may require higher amounts to achieve beneficial results. Since isoflavones are eliminated from the body quickly, some physicians recommend taking soy isoflavones in two to three separate doses to maintain blood levels throughout the day.
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 The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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