Fish Oil with Higher DHA Content and Voluntary Exercise Decreases Postmenopausal Bone Loss

Abstract

There is increasing evidence suggesting that fish oil (FO) decreases bone resorption by reducing osteoclastogenesis and regular exercise (EX) increases bone mass. EX is associated with increasing bone formation. Therefore, the combined effects of FO intake and EX may have additive effects by both increasing bone formation and decreasing bone resorption. To demonstrate this, we studied the effects of FO and EX on the bone of mice after an ovariectomyinduced bone loss. Twelve months old C57BL/6 female mice were either sham operated or ovariectomized, divided into different dietary and EX group and maintained for 3 months before sacrifice. The distal femoral metaphysis (DFM) showed significantly higher total BMC in both the FO sham sedentary groups. 30/20 ovariectomized sedentary mice had higher total bone mineral content (BMC). EX significantly increased BMC in the control and one of the FO ovariectomized (18/12) groups. The total bone mineral density (BMD) was higher in both the FO ovariectomized mice. EX significantly increased BMD in the control and combination with 18/12 ovariectomized groups. Cortical BMC increased after EX with both FO diets. The DFM showed no significant changes in the trabecular thickness. However, the trabecular number increased in mice fed both FO diet and on EX. Trabecular separation was decreased in the control and 30/20 FO-fed animals but increased in the 18/12 FO-fed mice. In conclusion, in the distal femoral metaphysis, FO-fed mice showed increased BMD. In combination with EX, the 30/20 FO-fed mice showed higher trabecular number and cortical bone mass as well as decreased trabecular separation.