The clinical trial - involving 248 women aged 45 to 60 with five years of menopause - found that taking a daily soy supplement did not slow bone loss or ease hot flashes.
Menopause, defined as the cessation of the menstrual cycle for 12 consecutive months, is often accompanied by rapid bone loss and hot flashes among other symptoms.
A hot flash is typically a feeling of intense heat with sweating and rapid heartbeat that lasts from two to thirty minutes. Heat is usually felt in the face or chest, but can also occur in the back of the neck and can spread throughout the body. Roughly 85% of women will experience hot flashes and among them, 20 percent will seek treatment.
While estrogen therapy - with or without progesterone - prevents most of these symptoms, the overall risks of hormone therapy outweigh its benefits. As a result, many women seek alternatives including foods and supplements.
Hopes have been high that soy might be a safe and effective alternative to estrogen. The fact that women in Asia experience fewer hot flashes and have lower rates of osteoporosis, breast cancer and heart disease has been attributed to their soy-rich diet.
Soy protein contains phytoestrogens called isoflavones, natural compounds that can bind weakly to estrogen receptors in the body. In so doing, soy isoflavones might offer some of estrogen's positive effects such as relief from hot flashes and delayed bone loss. Earlier findings on soy intake and menopausal symptoms have been mixed.
The current study, published this week in Archives of Internal Medicine, assigned 248 postmenopausal women to a daily 200 milligram soy isoflavone supplement or a placebo. The isoflavone dose was equivalent to twice the highest intake through food sources in the typical Asian diet. Women in both groups had sufficient calcium and vitamin D intake.
After two years, there were no differences to changes in bone density in the spine, hip or femoral neck between the groups. Soy isoflavones also had no effect on hot flashes. Women taking soy did not experience fewer hot flashes, whereas those in the placebo group did.
While soy doesn't appear to be the promising supplement for menopause we once thought, other dietary and lifestyle modifications may help ease menopausal symptoms. To learn more, pick up a copy of my book, The Complete Nutrition Guide to Menopause.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.