Protective Effect of Vitamin E in Combination with Vitamin D and Calcium Against Osteoporosis in Ovariectomized Rats

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Abstract
Background and Objective: The lack of estrogen after menopause is associated with bone fractures and osteoporosis. This study was conducted to evaluate the protective effects of vitamin E (a-tocopherol, VE) in combination with calcium (Ca), Vitamin D (VD) or both of them on osteoporosis in ovariectomized (OVX) rats. Materials and Methods: Forty two rats were randomly divided into 6 equal groups (n = 7). Bilateral ovariectomy and sham (SHAM) surgery were performed in rats. Group 1 was SHAM-operated (negative control), while the other 5 groups were OVX-operated. Three weeks post-ovariectomy, group 2 was kept as a positive control (OVX) and groups 3, 4 and 5 were fed on diets supplemented with the following treatments: VE+Ca, VE+VD and VE+VD+Ca, respectively for 6 weeks. In the experimental diet, 210 mg kg–1 calcium carbonate, 600 IU kg–1 cholecalciferol and 1000 mg of "-tocopherol acetate were used. Group 6 was orally given alendronate (standard anti-osteoporotic drug) in a single weekly dose (3 mg kg–1) for 6 weeks. At the end of the feeding period, blood samples were collected to estimate serum markers related to osteoporosis diagnosis. Femur bones were dissected out to estimate of bone density and bone mineral levels. Results: The supplementation of diet with VE, VD and Ca antagonized the increase in body weight gain and the decrease in uterine weight induced by ovariectomy. The three dietary supplements also significantly elevated the serum Ca, phosphorous, bone-specific alkaline phosphatase and osteocalcin but lowered the high serum interleukin-1β, interleukin-6 and pyridinoline levels in OVX-rats. Serum free thyroxin and calcitonin were significantly elevated and parathormone was decreased when the three dietary supplements were fed to OXV-rats. There were also significant increases in femoral bone density, Ca and phosphorous contents in bone ash in all supplemented groups rather than OVX control group, with no significant difference between the three dietary supplements group and alendronate given group. Conclusion: The supplementation of VE with Ca, VD or both exert antiosteoporotic effects in OVX rats. This activity might be due to enhancement of bone formation and suppression of bone loss, which together could be helpful for the prevention of osteoporosis in postmenopausal women due to estrogen deficiency.

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