Genistein aglycone effect on bone loss is not enhanced by supplemental calcium and vitamin D3: A dose ranging experimental study

Genistein aglycone (GEN) has a favorable effect on bone loss. We investigated the effects of GEN alone or in combination with supplemental calcium and vitamin D-3 in an animal model of bone loss to evaluate if there was additional benefit. Ovariectomized (OVX) and SHAM-OVX rats were used. OVX were divided into 12 groups and randomized to receive: GEN at 27, 54, 200, 500 or 1000 mg (human equivalent dose (HED)/day/ip injection alone or with calcium carbonate (Ca)(360 mg/kg/day/gavages)and vitamin D-3 (D-3) (50 IU/kg/day/gavages) or Ca/D-3 without GEN or untreated for 6 weeks. SHAM-OVX were randomized into 7 groups and treated with: Ca and D-3 alone or in combination with GEN (same doses as OVX), or left untreated. Bone mineral density (BMD), bone-alkaline phosphatase (b-ALP), collagen C-telopeptides (CTX), osteoprotegerin (OPG) and soluble receptor activator of NF kappa B ligand (sRANKL) were assessed. Femurs were excised and tested for breaking strength and histology. Uterine weight was analyzed to assess GEN's estrogenic effects on the SHAM-OVX. The most effective dose of GEN, independent of Ca/D-3 supplementation, was 54 mg/day. Higher closes yielded no further improvement in bone biomarkers. histology or strength. Only 1000 mg/day HED of genistein produced statistically significant changes in uterine weight of the SHAM-OVX. This study suggests that 54 mg/day of GEN is the threshold dose for efficacy. In addition, supplemental calcium and vitamin D-3, beyond normal dietary intake do not enhance the effects of genistein on improving measures of bone loss. This observation has implications regarding the use of calcium and vitamin D-3 supplementation. (C) 2011 Elsevier GmbH. All rights reserved.