The association between soy nut consumption and decreased menopausal symptoms

Background: Epidemiological studies suggest a low incidence of hot flashes in populations that consume dietary soy. The present study examined the effect of soy nuts on hot flashes and menopausal symptoms. Methods: Sixty healthy postmenopausal women were randomized in a crossover design to a therapeutic lifestyle changes (TLC) diet alone and a TLC diet of similar energy, fat, and protein content in which one-half cup soy nuts divided into three or four portions spaced throughout the day ( containing 25 g soy protein and 101 mg aglycone isoflavones) replaced 25 g of nonsoy protein. During each 8-week diet period, subjects recorded the number of hot flashes and amount of exercise daily. At the end of each 8-week diet period, subjects filled out the menopausal symptom quality of life questionnaire. Results: Compared to the TLC diet alone, the TLC diet plus soy nuts was associated with a 45% decrease in hot flashes (7.5 +/- 3.6 vs. 4.1 +/- 2.6 hot flashes day, respectively, p < 0.001) in women with > 4.5 hot flashes/day at baseline and 41% in those with <= 4.5 hot flashes/day (2.2 +/- 1.2 vs. 1.3 +/- 1.1, respectively, p < 0.001). Soy nut intake was also associated with significant improvement in scores on the menopausal symptom quality of life questionnaire: 19% decrease in vasomotor score ( p = 0.004), 12.9% reduction in psychosocial score ( p = 0.01), 9.7% decrease in physical score ( p = 0.045), and a trend toward improvement in the sexual score, with a 17.7% reduction in symptoms ( p = 0.129). The amount of exercise had no effect on hot flash reduction. Conclusions: Substituting soy nuts for nonsoy protein in a TLC diet and consumed three or four times throughout the day is associated with a decrease in hot flashes and improvement in menopausal symptoms.