It was a hypothesis based on the fact that, overall, women of Asian ancestry report fewer menopausal symptoms than women of European background, scientists say.
With the onset of menopause, women's hormone levels drop precipitously. Given that Asian women consume diets notably high in soy products -- which also happen to be rich in plant-based estrogen -- scientists had long hypothesized that it was their dietary intake of estrogen that helped make up for the shortfall and ease menopausal symptoms.
However, after studying the relationship between soy intake and menopause in 1,600 women over 10 years, scientists from the University of California Davis say they found no consistent link between the consumption of plant-based estrogen and the reduction of menopausal symptoms.
"Given that most women experience unpleasant symptoms, particularly hot flashes and night sweats, during menopause, we were hopeful that certain dietary intakes would provide good alternatives to hormone therapy," said Ellen Gold, lead author of the study.
"Unfortunately, based on our study, soy-related foods did not turn out to be the 'magic bullet.'"
The study was published online ahead of its appearance in the March 2013 print edition of Menopause: The Journal of The North American Menopause Society.
Plant-based estrogens are mainly found in food sources like tofu and soymilk and are believed to mimic the effects of the female hormone in the body.
The study also took into account participants’ fiber intake, as it’s thought to increase the availability of estrogen in the body.
In addition to following a large number of women over a long period of time, the study also included women from different ethnic backgrounds, including white, African-American, Hispanic, Chinese and Japanese participants.
Meanwhile, a 2010 study out of China published in the Canadian Medical Association Journal found that soy isoflavones helped ward off recurrence of breast cancer in post-menopausal women.