Comparative Study of Artherogenic Effects of Common Nigerian Edible Oils in Male Rabbits

Aims: To compare the atherogenicity of edible oils namely, palm, groundnut and egusi melon oils in male rabbits by determining their lipid profile and presence of atherosclerosis in their aortas.

Methodology: Twenty-five 8 weeks old male rabbits divided into five groups were used. Group A served as control and was fed on normal chow. The remaining four groups were fed on normal chow fortified with cholesterol, palm oil, groundnut oil or egusi melon oil respectively. At the end of 12-weeks, animals were fasted overnight and their blood samples were assayed for total cholesterol (TC), high- density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels. Atherosclerotic lesions of the vascular walls were classified according to American Heart Association (AHA) classification.

Results: The TC was significantly lower in egusi melon oil group (63 ± 19 mg/dl) than in controls (103 ± 8.8 mg/dl) with p-value < 0.001. They also had the lowest non-HDL-C (38 ± 19 mg/dl), significantly lower than that of controls (87 ± 9.7 mg/dl), p-value< 0.001. The palm oil fed rabbits had the highest plasma HDL-C (33 ± 2.0 mg/dl) that was significantly higher than that of controls (17 ± 0.55 mg/dl) but not significantly different for animals fed on groundnut oil (27 ± 5.1 mg/dl) or egusi melon oil (25 ± 2.3 mg/dl). Rabbits fed on egusi melon oil had the lowest AI (1.5 ± 0.79).

Rabbits fed on palm oil had lower tunica intima (TI)/tunica media (TM) ratio than other groups p <0.001. Atherosclerotic changes in keeping with AHA type II lesions were found in aorta of rabbits on groundnut oil and egusi melon oil.

Conclusion: Egusi melon oil produced better plasma cholesterol lowering effect but still produced atherosclerotic lesion. No lesion was observed with palm oil supplemented diet possibly because the group had the highest level of HDL-C that is considered to reduce cardiovascular risk. Further evaluation of the test oils is needed to identify factors responsible for their beneficial and atherogenic effects.