Refined Palm Oil Significantly Increases Total and LDL-Cholesterol Compared to Crude Palm Oil in Male Wistar Rats

Abstract Background: Conflicting evidence exists regarding the effects of crude and refined palm oil on cardiovascular health. This study evaluated the impact of palm oil processing on serum lipid profiles in male Wistar rats. Methods: A parallel experimental study was conducted using 49 newly weaned male Wistar rats, of which 46 completed the study. Animals were housed under controlled conditions at the Central Animal House, College of Medicine, University of Ibadan, Nigeria. Following a 2-week run-in period, rats were assigned to seven groups (n = 7 per group) and fed diets containing 20% oil from different sources: control (CTL), palm kernel oil (PKO), crude palm oil (CPO), bleached palm oil (BPO), unsaturated palm oil (UPO), saturated palm oil (SPO), and refined palm oil (RPO) for 5 weeks. Serum lipid parameters: total cholesterol (TC), low-density lipoprotein cholesterol (LDLC), high-density lipoprotein cholesterol (HDLC), and triglycerides (TG) were analysed using standard enzymatic methods. Data were expressed as mean ± SD and analysed using one-way ANOVA followed by Tukey and Dunnet post hoc test, with p ≤ 0.05 considered significant. Results: Significant differences were observed in TC, LDLC, and HDLC across groups (p = 0.001, p = 0.001, and p = 0.010, respectively). There was no significant differences among the groups for TG (p = 0.55). Rats fed refined palm oil (RPO) exhibited significantly higher TC and LDLC levels compared to the control and other groups. HDLC levels were highest in the PKO group and lowest in the RPO group, with intermediate values observed in other groups. There was no significant difference in weight gain (p = 0.70 ) across all groups Conclusion: Refined palm oil consumption was associated with unfavourable alterations in serum lipid profiles, particularly elevated TC and LDLC, compared to other palm oil types. These findings suggest that processing and refinement may influence the cardiovascular health effects of palm oil.