In one study, 70 postmenopausal women took 30 mg of genistein, 800 IU of vitamin D3, 150 mcg of vitamin K1, and omega-3s comprised of 667 mg of EPA (eicosapentaenoic acid) plus 333 mg of DHA (docosahexaenoic acid) per day or a calcium placebo.
After six months, while the placebo group had a large decrease in bone mineral density (BMD), those in the genistein group had maintained BMD at the femoral neck, one of the narrowest and most vulnerable areas at the top of the thigh bone, or femur.
Scientists also saw an increase in signs of bone formation and re-mineralization in the genistein group, both compared to placebo and to the start of the study.