The Influence of Dietary Fat Source on Life Span in Calorie Restricted Mice

Calorie restriction ( CR) without malnutrition extends life span in several animal models. It has been proposed that a decrease in the amount of polyunsaturated fatty acids ( PUFAs), and especially n- 3 fatty acids, in membrane phospholipids may contribute to life span extension with CR. Phospholipid PUFAs are sensitive to dietary fatty acid composition, and thus, the purpose of this study was to determine the influence of dietary lipids on life span in CR mice. C57BL/ 6J mice were assigned to four groups ( a 5% CR control group and three 40% CR groups) and fed diets with soybean oil ( high in n- 6 PUFAs), fish oil ( high in n- 3 PUFAs), or lard ( high in saturated and monounsaturated fatty acids) as the primary lipid source. Life span was increased ( p <.05) in all CR groups compared to the Control mice. Life span was also increased ( p <.05) in the CR lard mice compared to animals consuming either the CR fish or soybean oil diets. These results indicate that dietary lipid composition can influence life span in mice on CR, and suggest that a diet containing a low proportion of PUFAs and high proportion of monounsaturated and saturated fats may maximize life span in animals maintained on CR.