The most recent findings on soy and isoflavones were presented in Washington DC on the occasion of the 9th International Symposium on the Role of Soy in Health Promotion and Chronic Disease Prevention and Treatment (October 16-19, 2010). A major part of the topics was dedicated to safety and health benefits in menopausal women, and to the issue of soy and breast cancer.
A clinical trial presented by Dr. Seema Khan (Feinberg School of Medicine, Northwestern University, Chicago) focused on the effect of isoflavones on genetic markers of breast cancer development in women at high risk (Khan et al. 2010). 126 women at high risk for breast cancer underwent fine needle aspiration of the unaffected breast, with samples taken in the mid-luteal phase. Patients with >4,000 epithelial cells were randomized to a six-month intervention of a soy isoflavone supplement (Solae) with 150 mg isoflavones daily versus placebo. Cells were stained for Ki-67, and examined by RT-PCR for 32 genes related to proliferation, apoptosis and estrogenic effects.
Data from 98 women (49 in each group) were evaluated. In the total population no significant difference was found for the Ki-67 labelling index: under isoflavones it was reduced from 1.18 to 1.12, whereas in the placebo group it decreased from 0.97 to 0.92 (p = 0.32). No significant changes in gene expression were found in either group. Overall, the findings do clearly not support the hypothesis of a specific risk involved in the use of isoflavones by women at high risk of breast cancer.
References
Khan SA, Michel N, Michele B, Lee O, Chatterton RT, Ivancic D, Zalles C, Jovanovic B and Bergan R (2010). A phase IIb trial of G-2535 (unconjugated isoflavones-100) in women at high risk for breast cancer. 9th International Symposium on the Role of Soy in Health Promotion and Chronic Disease Prevention and Treatment, Washington DC, 16-19 October.
Safety 