Research paper
Long-term soy isoflavone supplementation and cognition in women
Study answer
What this study found
Long-term ISP did not improve global cognition in healthy postmenopausal women. The primary global cognition outcome at 2.5 years was not significant: mean standardized difference 0.11, 95% CI -0.13 to 0.35, p = 0.36. Visual memory showed a favorable secondary effect for ISP (mean standardized difference 0.33, 95% CI 0.06-0.60), but other cognitive factors and individual tests were not significantly different. Overall, the findings do not support ISP for global cognitive benefit in this population.
- Study & population
- Randomized, placebo-controlled trial in healthy postmenopausal women, including natural and surgical menopause, conducted at the University of Southern California in Los Angeles.
- Intervention
- The active intervention was 25 g/day of isoflavone-rich soy protein (ISP) taken orally as powder or bar form for 2.5 years, providing 91 mg/day aglycone-weight isoflavones (total isoflavone equivalents 154 mg/day; genistein 52 mg, daidzein 36 mg, glycitein 3 mg).
- Key limitation
- Attrition reduced the analyzed sample relative to randomization in both arms, and cognitive benefit was limited to a secondary endpoint.
View source
Open PDFOriginal abstract
Objective: To determine the cognitive effects of long-term dietary soy isoflavones in a daily dose comparable to that of traditional Asian diets. Methods: In the double-blind Women's Isoflavone Soy Health trial, healthy postmenopausal women were rand…