Long-term responses of rats to heat-treated dietary fats: IV. Weight gains,food and energy efficiencies,longevity and histopathology

Representative cottonseed salad oils, corn oils, lards and hydrogenated vegetable shortenings, and portions of the same fats heated at 182 C for 120 hr were fed as 20% of nutritionally adequate diets to weanling albino rats in longevity studies. Differences in the responses of rats fed diets containing the unheated and heated fats were generally small with respect to rates of gain, 12 th week and adult weights, efficiencies of utilization of absorbed energy, incidences of grossly detectable diseases and longevities. There were no indications that the feeding of the heated fats had shortened survival times in comparison with the comparable unheated fat. Animals fed hydrogenated vegetable shortening, heated or unheated, survived the longest. However, gains were slightly slower with the heated cotton-seed oil diets, and food efficiencies were slightly lower with the heated cottonseed oil and heated lard diets because of decreased digestibilities of these fats. The usual disabilities of old age such as nephritis, respiratory disease and periarteritis were present in all groups. The incidence of mammary tumors was high but did not differ significantly with the kind of fat, heaated or unheated. Tumor incidence other than mammary was similar in both sexes and there was no significant difference between fresh and heated fats. Absence of adverse effects attributable to the heated fats during the life span of the rats in further evidence of the safety of these fats of the quality customarily consumed by the human population.