Effects of Plant-derived Frying Oils on the Bone Structure of Normal Male Rats

Abstract

Vitamin E has been shown to have anabolic action on bone of normal male rats. The presence of vitamin E in palm and soy oil, the commonly used plant-derived frying oils have rendered them more resistant to oxidation when repeatedly heated. Previous studies have shown that repeatedly heated frying oils had caused bone loss in ovariectomised rats. This was believed to be contributed by the generation of free radicals in the heated frying oils. Our study aimed to evaluate the effects of repeatedly heated palm and soy oils on the bone of normal male rats. Methods: Forty-two male Sprague-Dawley rats were randomly assigned into seven groups according to their diet; normal control (NC), fresh palm oil (FPO), fresh soy oil (FSO), five times heated palm oil (5HPO), five times heated soy oil (5HSO), ten times heated palm oil (10HPO) and ten times heated soy oil (10HSO). The rats were fed for six months with rat chow mixed with the respective oils at 15% (w/w). Bone structural changes were assessed by performing histomorphometry on the rat femora. The parameters measured were Trabecular volume (BV/TV), Trabecular thickness (TbTh), Trabecular separation (TbSp) and Trabecular Number (TbN). Results: There were no significant differences in all the structural histomorphometric parameters of the repeatedly heated oils groups when compared to normal control and fresh oils groups. Conclusion: Repeatedly heated palm and soy oils are safe and not detrimental to the bone structure of normal male rats. The vitamin E content in the oils may be responsible for these bone protective effects.