Soy product intake and hot flashes in Japanese women: Results from a community-based prospective study

The association between soy product intake and the occurrence of hot flashe s was examined in a cohort of 1,106 female residents of Takayama, Gifu, Jap an. The women were aged 35-54 years and premenopausal at their entry into t he study in 1992. Diet, including intake of soy products and isoflavones, w as assessed by means of a validated semiquantitative food frequency questio nnaire at study entry. A follow-up mail questionnaire asking about experien ces of hot flashes was sent in 1998. During the 6 years of the study period , 101 women had new moderate or severe hot flashes according to the Kupperm an test of menopausal distress. After data were controlled for age, total e nergy intake, and menopausal status, hot flashes were significantly inverse ly associated with consumption of soy products in terms of both total amoun t (highest tertile of soy product intake (g/day) vs. lowest: hazard ratio = 0.47; 95% confidence interval: 0.28, 0.79; p for trend = 0.005) and isofla vone intake (highest tertile of isoflavone intake (mg/day) vs. lowest: haza rd ratio = 0.42; 95% confidence interval: 0.25, 0.72; p for trend = 0.002). These data suggest that consumption of soy products has a protective effec t against hot flashes.