Clinical and histopathological observations with rats fed laboratory heated or deep-fry fats

A purified diet containing 15% by weight of experimental fats was fed to male weanling rats for 28 days. The fats used were fresh or laboratory-heated corn oil (FCO, HCO) and fresh, laboratory-heated, single-fry or double-fry partially hydrogenated soybean oil (FHSBO, HHSBO, SHSBO, DHSBO). HCO and HHSBO significantly depressed total weight gain, feed consumption and feed efficiency. Fats obtained from the commercial pressure deepfry operation producing fried chicken (SHSBO, DHSBO) resulted in values for the above parameters comparable to those for controls. Ingestion of the laboratory-heated fats increased relative weights of the livers and testes. Kidney weights were lighter in animals fed FHSBO, SHSBO and DHSBO. Dietary HCO, FHSBO, and HHSBO were associated with lighter thymus glands. Neither the test nor control fats affected heart weights. Although the values were not statistically different, HCO, HHSBO and SHSBO decreased numerically the total white blood cell count below normal, and the differential white cell counts revealed also reductions in the levels of lymphocytes. As a result of feeding rats HCO or HHSBO, various signs of heated fat toxicity such as wet abdominal and perineal areas, diarrhea, dermatitis, seborrhea, hair loss and irritability were apparent. Histopathology of selected tissues revealed lesions induced in the thymus by HHSBO, in the spleen by FHSBO and HHSBO, in the liver by HCO, HHSBO and DHSBO, and in the skin by FHSBO and HHSBO.