Histopathological manifestations of liver tissue affected by heated and unheated palm oil in Wistar rats

Abstract Palm oil is the most widely used type of oil in the world, which is oxidized by exposure to heat and leads to damage to body tissues and the creation of free fatty acids. This study aimed to show the harm of palm oil in both heated and non-heated states. For this purpose, twenty-four male Wistar rats were randomly divided into three groups and treated as follows: control (rats treated with their normal chew), palm oil (rats treated with 7.5% w/w of palm oil added to their normal chew), and heated palm oil (rats treated with 7.5% w/w of palm oil into their normal chew, which had been heated repeatedly 10 times at 180°C for 10 min). After experimental treatments, the animals were euthanized. Liver samples were collected for histopathological assessment by hematoxylin and eosin (H&E) staining. In the groups treated with heated and unheated palm oil, signs of non-alcoholic fatty liver disease were observed at different proportions. Histological evidence is an indication that heated and unheated palm oils can cause various degrees of non-alcoholic fatty liver disease. Therefore, the consumption of palm oil, especially when heated, may not be completely safe.