Dietary fish oil results in a greater bone mass and bone formation indices in aged ovariectomized rats

Abstract

Postmenopausal bone loss and the possible progression to osteoporosis is a major health concern. Until recently, hormone replacement therapy (HRT) was the standard for preventing the development of osteoporosis and possible hip fractures following menopause. However, because of some adverse effects of HRT, new therapies, lifestyle habits, and nutritional interventions are being developed and better characterized in their ability to prevent bone loss after menopause. One such option is to increase the amount of fish oil consumed in the diet. The goal of the current research was to determine the impact of fish oil supplementation on bone mass, density, formation, and resorption in an aged ovariectomized rat model. Twelve-month-old female retired breeder Sprague-Dawley rats were fed a control (Control) or fish oil (Fish) diet. Two weeks following the introduction of the diets, the rats were either sham-operated (Sham) or bilaterally ovariectomized (OVX). Ten weeks after surgery, indices of bone mass and bone histomorphometry were measured. Bone mineral content (BMC) of the whole femur was significantly higher in the Fish/OVX than in the Control/OVX, and the differences were most pronounced in the distal and proximal ends of the femur. However, the Fish/Sham and the Control/Sham did not differ in the measures of BMC. Although the Control/OVX had significantly lower cortical area and greater endosteal perimeter compared with the Control/Sham, the differences were not significant between the Fish/Sham and the Fish/OVX. In addition, the Fish/OVX had a significantly larger percent double-labeled surface and mineral apposition rate at the endocortical surface than the Control/OVX. Our findings suggest that fish oil supplementation has a positive effect on bone metabolism and might be a possible intervention to slow the loss of bone observed following menopause.