Diets Differently Affect Bone Health: Murine Models

Bone is a dynamic specialized connective tissue that undergoes continuous remodeling to preserve its health. Bone health is influenced throughout life by a combination of genetic, hormonal, and environmental factors, as well as physical activity and diet. This study aims to evaluate the effects of diets with different fat content on the femurs of mice fed for 16 or 20 weeks on a normal diet (ND16w and ND20w) or a Western diet (WD16w and WD20w) and for 20 weeks with their combinations on a ketogenic diet (KD) (WD + ND20w, ND + KD20w, and WD + KD20w). Micro-CT analysis on femoral cancellous bone revealed a non-significant trend toward decreased bone volume fraction (BV/TV) and trabecular thickness in mice fed a combined WD + KD20w compared to WD20w. Cortical bone thickness was significantly lower in mice fed WD16w and WD20w compared to those fed ND16w and ND20w (p = 0.049 and p = 0.039, respectively), in mice fed WD20w Ct.Th increased compared to WD + ND20w (p = 0.024) and a strong decrease is evident when comparing WD + ND20w to WD + KD20w (p < 0.0004). Consistently, histological analysis revealed that the number of osteoclasts per bone perimeter on cancellous bone increases compared with ND20w with ND + KD20w (p = 0.007) and WD + ND20w with ND + KD20w (p = 0.0006). In addition, a decrease in osteoblasts was observed (p < 0.041) in cortical bone, comparing ND20w with ND + KD20w; this suggests that the KD may have differential effects depending on the baseline condition. Osteocyte numbers did not significantly change when comparing the different treatments. Masson staining supports micro-CT results on both cortical and cancellous bone. In conclusion, transition from a high-fat diet to a normal diet may partially restore cortical bone health, whereas transition to a ketogenic diet exerts a trend toward additional detrimental effects on trabecular bone.