ARS | Publication request: Isoflavones supplements do not, but appetitive hormones do, influence overall and central adiposity in healthy postmenopausal women

Submitted to: The Journal of the North American Menopause Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 3, 2009
Publication Date: June 1, 2010
Citation: Matvienko, O.A., Alekel, D.L., Genschel, U., Ritland, L., Van Loan, M.D., Koehler, K. 2010. Isoflavones supplements do not, but appetitive hormones do, influence overall and central adiposity in healthy postmenopausal women. The Journal of the North American Menopause Society. Vol. 17, No. 3, pp. 594-601.

Interpretive Summary: Nutrition information can be found in the news media on a daily basis much of which suggests beneficial effects of a particular supplement. Soy beans, soy protein and soy isoflavones have been promoted as having health benefits ranging from reduction of bone loss to reduction in body weight. Soy isoflavones are thought to play a role in body weight regulation by modulating appetite hormones that circulate in blood. We conducted a study with soy isoflavones supplements for 1 year and monitored changes in body fat and lean mass and appetite hormones in a group of 229 healthy postmenopausal women. Soy supplements where either 80 mg/day or 129 mg/day and compared to a matching placebo tablet. At the end of 1 year there were no difference in whole body lean mass or fat mass across the 3 treatment groups nor was there any difference in body fat distribution from upper body, primarily abdomen, to lower body mostly hips and thighs. No difference was found in blood levels of appetite regulating hormones with soy isoflavones treatment group compared to the placebo group. Although soy isoflavones may have some health benefits it does not appear as though body fat nor appetite regulating hormones are influenced by these compounds.

Technical Abstract: Background: Soybeans are promoted as a healthy food with multiple health benefits. One of the claimed benefits is that soy protein or isoflavones may favorably affect body composition. Objective: We examined the effect of soy isoflavone supplements on overall and regional body composition taking into account appetitive hormones as potential mediators. We also assessed the effect of isoflavone treatment on circulating concentrations of appetitive hormones. Design: This randomized, double-blind, placebo-controlled multi-center trial included 229 healthy postmenopausal women (45.8-65 y, BMI 24.9±3.0) who consumed placebo or soy isoflavones (80 or 120 mg/d) for 12 mo. We used intent-to-treat analysis to examine outcomes including body composition (whole body lean mass, whole body fat mass, androidal fat mass, androidal-to-gynoidal fat mass ratio) and appetitive hormones (insulin, leptin, ghrelin, adiponectin). Results: Repeated measures ANOVA indicated that soy isoflavone treatment did not exert a significant effect on any of the body composition measures (P value ranged from 0.36 to 0.79) or appetitive hormone concentrations; the inclusion of covariates in statistical models did not alter these results. Appetitive hormones (leptin [P<0.0001], adiponectin [P=0.0004, P<0.0001], ghrelin [P value ranged from 0.017 to 0.044]), time since menopause (P=0.0027, P=0.0055), and dietary fat (P=0.017, P=0.028) contributed significantly to body composition outcomes independently of treatment. Conclusions: Our findings do not support a favorable effect of soy isoflavone supplements consumed for 12 mo on body composition in healthy postmenopausal women.