Effects of the phytoestrogen genistein on the circulating soluble receptor activator of nuclear factor κB ligand-osteoprotegerin system in early postmenopausal women

We investigated the serum levels of both receptor activator of nuclear factor kappaB ligand ( RANKL) and its decoy receptor osteoprotegerin (OPG) in postmenopausal healthy women after a 1-yr therapy with genistein, (n = 30; 54 mg/d), hormone replacement therapy (n = 30; 1 mg/d 17beta-estradiol combined with norethisterone acetate) and placebo ( n = 30). By comparison with placebo, the soluble RANKL (sRANKL)/OPG ratio was lower in the genistein group (-69 +/- 7%; P < 0.01 vs. placebo 81 +/- 24%) and in hormone replacement therapy-treated women ( - 11 +/- 2%; P < 0.01 vs. placebo). A positive correlation (r = 0.63; P < 0.01) was found between 1-yr percentage change in sRANKL/OPG ratio and 1-yr change in urinary deoxypyridinoline, a bone resorption marker. A negative correlation was observed between 1-yr percentage change in sRANKL/OPG ratio and 1-yr change in femoral neck bone mineral density ( r = - 0.7; P < 0.01). Our findings suggest that the sRANKL-OPG system may mediate the beneficial effects of genistein on bone remodeling in postmenopausal women.