Effect of soy-derived isoflavones on hot flushes, endometrial thickness, and the pulsatility index of the uterine and cerebral arteries

Objective: To determine the effect of soy-derived isoflavones on hot flushes, endometrial thickness, and the vascular reactivity of uterine and cerebral arteries. Design: Double-blind, randomized, placebo-controlled trial. Setting: Healthy volunteers in an academic research environment. Patient(s): Sixty-two postmenopausal women aged 45–60 years attending the Outpatient Menopause Clinic of our gynecological departments. Intervention(s): The patients were administered 72 mg of soy-derived isoflavones or placebo under double- blind conditions. The daily number of hot flushes was recorded in a diary. Endometrial thickness was measured by means of transvaginal ultrasound; the uterine, internal carotid, and middle cerebral arteries were evaluated using Doppler ultrasound. Main Outcome Measure(s): The daily number of hot flushes, endometrial thickness, and arterial pulsatility index (PI). Result(s): Both treatments led to a 40% reduction in the number of hot flushes. Soy-derived isoflavones had no effect on endometrial thickness or the PI of the uterine and cerebral arteries. Conclusion(s): The daily administration of 72 mg of soy-derived isoflavones is no more effective than placebo in reducing hot flushes in postmenopausal women. It also has no effect on endometrial thickness or the PI of the uterine and cerebral arteries.