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But when it comes to supplements, research finds that soy isoflavone tablets do not appear to be associated with a reduction in bone loss or menopausal symptoms in women within the first five years of menopause.
According to a Florida study published in the Archives of Internal Medicine, the beginning stages of menopause are often accompanied by rapid bone loss, hot flashes, vaginal dryness, and sleep disturbances, among other symptoms.
Many doctors prescribe estrogen therapy with or without progesterone to try to prevent most of these changes. According to the study authors, most menopausal women are increasingly seeking other alternatives, such as soy. That's because the Women's Health Initiative found that the overall risks of hormone replacement therapy outweigh the benefits.
In the University of Miami randomized controlled trial, study participants received either a placebo or a daily soy isoflavone dose of 200 mg.
That's equivalent to approximately two times the highest intake through food sources in a typical Asian diet. Soy is often credited with the low rates of breast cancer and menopausal symptoms in Asian women.
Soy isoflavones are a type of phytoestrogen, which are plant substances that act like a weaker form of estrogen in the body.
But in this study, during two years of follow-up, no significant differences were found between women in the soy isoflavone group and placebo group regarding changes in bone mineral density.
Nor did the soy isoflavones relieve menopausal symptoms. In fact, hot flashes were actually greater in the soy group.
Some soy advocates believe that food sources of soy may be more effective as an estrogen substitute to help midlife women deal with their menopause symptoms.
But there are good reasons to minimize dietary soy.
For one thing, well over 90% of the soy in the U.S. is genetically modified.
And soy may interfere with thyroid function which is already a problem for many menopausal women. This is because it's a goitrogen, a substance that block the synthesis of thyroid hormones. It also interferes with iodine metabolism, further interfering with thyroid function.
While soy is often credited with fewer and milder symptoms of menopause among Asian women, there may be more to that story. According to Kaayla Daniel, Ph.D. and author of The Whole Soy Story, Asians actually eat less soy than Americans.
That's because processed soy has made its way into over 2,700 fast foods and processed food products in this country. In Asia on the other hand, soy is usually eaten only after it has been fermented to remove the phytates.
Menopausal women should stick to naturally fermented organic soy products. These include:
- Tempeh, a fermented soybean cake with a firm texture and nutty, mushroom-like flavor.
- Miso, a fermented soybean paste with a salty, buttery texture (commonly used in miso soup).
- Natto, fermented soybeans with a sticky texture and strong, cheese-like flavor.
- Soy sauce, which is traditionally made by fermenting soybeans, salt and enzymes. Avoid soy sauce made artificially using a chemical process.
For more information on menopause, download Green Med Info's comprehensive research entitled Menopausal Syndrome.