Consumption of thermally oxidized palm oil diets alters biochemical indices in rats

Palm oil is thermally oxidized to increase its palatability and this has been a usual practice in most homes. This study sought to assess the biochemical responses of rats to thermally oxidized palm oil diets. Therefore, Wistar strain albino rats (Rattus norveigicus) were fed with fresh palm oil (control) and thermally oxidized palm oil (test groups) diets and water ad libitum for 30 days. Then, the malondialdehyde (MDA) contents and total protein of the plasma and liver were determined. Subsequently, the plasma liver function markers [alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), albumin (ALB) and total bilirubin (TBIL) ] and the lipid profile [triglyceride (TRIG), total cholesterol (T-CHOL), high density lipoprotein (HDL-CHOL) and low density lipoprotein (LDL-CHOL) ] were assayed. The results of the study revealed that there was a significant decrease (P < 0.05) in the plasma and liver total protein, ALB, TRIG and HDL-CHOL of the test groups when compared with the control. Conversely, there was a significant increase (P < 0.05) in the activities of ALT, AST and ALP, TBIL, T-CHOL, LDL-CHOL and plasma/liver MDA of the test groups when compared with the control. These effects were most pronounced in rats fed with 20 min-thermally oxidized palm oil diet. Hence, consumption of thermally oxidized palm oil diets had deleterious effects on biochemical indices in rats. Therefore, cooking with and/or consumption of palm oil subjected to heat treatment for several long periods of time should be discouraged in our homes as this might have deleterious effects on human health.