Rethinking the Role of Soy After Menopause

Soy is commonly recommended to post-menopausal women for its estrogenic properties. Consequently, it is believed by some to potentially inhibit menopausal symptoms, reduce the risk of body fat gain, and improve heart disease risk in this population. Although previous studies may support such beliefs, two recent studies have reported that soy is ineffective.
Researchers studied the effects of soy isoflavones on the body composition of 229 post-menopausal non-obese women. Participants were randomly assigned to consume a once daily tablet that contained either 80 mg or 120 mg of soy isoflavone, or placebo for 12 months.
In addition to recording changes in body composition, appetite-controlling hormones such as insulin, leptin, ghrelin and adiponectin were assessed. Although the soy did significantly affect some hormones, researchers determined that only one factor influenced changes in body fat; the amount of dietary fat consumed. Hence, soy does not appear to have a significant impact on body fat.
In a second study published in the same journal, researchers determined that soy isoflavones did not improve the lipid profile in post-menopausal women with mildly high cholesterol. Sixty-two women were recruited to eat either soy-based foods or control-foods for 1 year.

After 12 months, participants on the soy-based diet saw slight increases in both total cholesterol and HDL cholesterol, but no changes in LDL or triglycerides were apparent. Because the changes did not achieve levels of significance it was determined that soy is not beneficial to reducing heart disease risk in post-menopausal women.
Although soy remains an adequate source of protein, there are definitive limitation to its use in the treatment of menopausal symptoms and consequences that include fat-weight gain and increased heart disease risk.