Acute Physiological Effects of Feeding Rats Non-urea-adducting Fatty Acids (Urea-Filtrate)

Abstract

Experiments were conducted to further describe the biological response to toxic components of severely heated fats. Much of the toxicity of severely heated food oils has been associated with a non-urea-adducting fatty acid (urea filtrate) fraction. Feeding this fraction on two consecutive days to weanling rats caused inanition, fatty liver, a decline in body temperature and death within 2 to 7 days. In this study the LD₅₀ of the fraction, administered orally, was approximately 0.6 ml/100 g/day for 2 days for rats weighing 40 to 50 g; from 60 to 100 g the LD₅₀ was approximately 0.9 ml/100 g/day for 2 days. Water consumption had little or no effect upon survival or level of liver fat, whereas forced feeding of non-lipid food elements decreased mortality and prevented the increase of liver lipid. A four- to fivefold elevation in neutral fat accounted for the increased liver fat. No unidentified fatty acids of the urea filtrate were detectable in the liver. The urea filtrate caused a 30% reduction in the conversion of palmitic-1-¹⁴C acid to ¹⁴CO₂ in the young rats during a 5.5-hour test period, whereas the oxidation of D-glucose-¹⁴C (uniformly labeled) to ¹⁴CO₂ was not affected. These results indicate that one or more of these non-urea-adducting fatty acids appreciably impaired the oxidation of fatty acids in young rats.