Soy supplements that contain isoflavones do not seem to help lower cholesterol, boost bone density and keep the mind sharp after menopause, new research from the University Medical Center in Utrecht suggests.
Isoflavones, compounds found in soybeans, chickpeas and other legumes, are similar to the female hormone estrogen. Because of this, researchers have been studying whether soy protein or supplements containing isoflavones might act as a sort of "natural" hormone replacement therapy, to counter the changes that often accompany the loss of estrogen in menopause.
However, this new study reported in the Journal of the American Medical Association suggests that this is not the case.
Studies have shown that Asian women, whose traditional diet is rich in soy, have a relatively low rate of hip fracture, breast cancer and heart disease. In addition, animal research has suggested that isoflavones might lessen bone loss related to waning estrogen levels.
Some studies of women, however, have found no evidence of bone benefits, and much of the research on isoflavones has involved only small groups of women followed for a relatively short time.
The researchers followed 202 healthy women between the ages of 60 and 75 for one year. Half of the women took 25.6 grams of soy protein in powder form every day, which contained almost 100 milligrams of isoflavones. The other half took a placebo, or inactive, supplement.
After one year, soy appeared no better than placebo in countering changes to bone mass, mental function or cholesterol levels, which often occur following menopause.
The researchers hypothesized that the soy powder may not have worked because the women featured in the study were very healthy, and the researchers may not have followed them for long enough to see the benefits soy can produce. Both bone density and cognitive function decline relatively slowly and a one-year intervention may not have been long enough to detect an effect.
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