SOURCE OF DIETARY CARBOHYDRATE AFFECTS LIFE-SPAN OF FISCHER-344 RATS INDEPENDENT OF CALORIC RESTRICTION

Previous investigations suggest that increased life span of calorie-re stricted rodents is a function of caloric intake rather than the macro - or micronutrient composition of the diet. However, tile dietary sour ce of carbohydrate has not Been widely investigated. We hypothesized t hat the dietary carbohydrate source may affect the life span of rats i ndependent of caloric restriction. This hypothesis was tested in male Fischer 344 rats fed ad libitum or restricted to 60% of ad libitum, an isocaloric diet containing 14% protein, 10% fat, and 66% sucrose or c ornstarch. Body weights of the ad libitum- and restricted-fed sucrose rats were consistently greater throughout the experimental period comp ared to diet-matched animals. Food intake did not differ significantly . The survival curves of ad libitum starch- vs sucrose-fed rats were s ignificantly different. That is, the mean, median and upper 10th perce ntile survival were significantly greater in the ad libitum starch- vs sucrose-fed rats (mean life span: cornstarch-fed, 720 +/- 23 days; su crose-fed, 659 +/- 19 days). Calorie-restricted starch-fed rats had po orer early life survival, and no significant increase in mean life spa n compared to ad libitum cornstarch-fed animals (726 vs 720 days). The se animals did, however, have the greatest upper 10th percentile survi val of all four experimental groups. Mean life span of calorie-restric ted sucrose-fed rats was significantly greater than that of all other groups (890 +/- 18 days). The differences in survival rates between su crose- and cornstarch-fed animals could not be attributed to the effec ts of carbohydrate source on body weight, energy absorption, or on the timing and severity of the pathological lesions normally associated w ith aging and/or caloric restriction in this species. These data suppo rt the hypothesis that the dietary source of carbohydrate, i.e., sucro se vs cornstarch, can significantly affect life span independently of caloric intake.