Abstract
BACKGROUND: High caloric intake of saturated fat and refined sugars accelerates the development of obesity and diabetes and increases bone fracture risk. Some evidence suggests that consumption of a diet rich in phytoestrogens like genistein has the potential to strengthen bone biomechanical properties. Its bone-strengthening properties may mitigate fracture risk associated with metabolic conditions like obesity and diabetes, especially when combined with exercise. OBJECTIVE: In this study, we test the effects of genistein, exercise training, and combination treatment on biomechanical properties of cortical bone in mice fed a high-fat, high-sugar (HFHS) diet. METHODS: Eighty C67BL6 mice (40 females, 40 males) aged 6 wk were treated for 12 wk with an HFHS diet containing 60% fat and drinking water with 4.2 g/L sugar (55% sucrose, 45% fructose). Subgroups of the mice were also treated with genistein and/or moderate exercise (treadmill running). Genistein was incorporated into the HFHS diet (600 mg genistein/kg HFHS) and exercise was performed daily for 30 min, 5 d/wk (n = 10 females, 10 males per group). Three-point bending mechanical testing and quantitative fluorescence microscopy were conducted on femurs to measure bone strength and matrix quality. RESULTS: Mechanical testing revealed HFHS-fed mice treated with genistein, either alone or combined with exercise, had femurs that exhibited increased postyield displacement and reduced stiffness during 3-point bending in comparison with mice only treated with the HFHS diet. Femurs of genistein-treated mice also exhibited greater ultimate force required to achieve fracture. Quantitative fluorescence showed genistein reduced advanced glycation end product accumulation in bone matrix. Exercise treatment alone had no effect. CONCLUSIONS: Treatment with genistein, either alone or in combination with exercise, improves fracture resistance in mice fed an HFHS diet by improving bone matrix quality and increasing bone strength.