Effects of life span feeding of ruminant-derived human diets to rats

A freeze-dried human diet, based on linoleic acid-enriched food stuffs derived from ruminants, was evaluated and compared with a similarly-prepared diet based on conventional ruminant-derived foodstuffs, using Porton rats in a whole-of-life study. A cereal-based stock diet was used for comparison. Serum biochemical and histopathological examinations were carried out at 0.25, 1.1 and 2.1 years of age and other rats were left until they died of natural causes. Although some diet-specific biochemical differences were noted, triglyceride and cholesterol levels showed changes which were more age-specific than diet-specific. Longevity did not seem to be influenced by quantity or quality of dietary fat. The most common cause of death was a bronchopneumonia at about 2 years of age. Dietary fat also did not affect incidence of tumors. The most common tumor was a pituitary adenoma which occurred most often in females. Only minor causes of death were specific to diet with waxy intra-cardial plaques occurring in less than 5% of rats fed both of the high-fat diets and severe systemic hypertension occurring in rats fed the low-fat stock diet at the same frequency. No deleterious changes were noted that were unique to the linoleic acid-enriched diet.