Comparative Study of Hepatic Fatty Acid Composition and Lipid Profile in Rats Fed Diets Rich in Palm Oil, Olive Oil, and Lard

The aim of our study was to determine the fatty acid (FA) composition of the liver, and the lipid profile of rats fed diets rich in palm oil, and to compare them with those of rats fed diets rich in olive oil and lard. Forty six-week-old male Wistar rats were divided into five groups (n = 8) and fed for 12 weeks with either a standard diet (385 kcal/100 g; 12% fat, 71% carbohydrates, and 17% protein) or a high-fat diet (525 kcal/100 g; 56% fat, 28% carbohydrates, and 16% protein). The lipids came exclusively from the oil tested in each group. Hepatic lipids were extracted using the Folch method and analysed by gas chromatography. Plasma lipid parameters (triglycerides, total cholesterol, HDL-C) were measured by automated spectrophotometry. Statistical analyses included Mann-Whitney tests (HFD vs. control comparison), Kruskal-Wallis tests (comparison between HFD groups), Spearman correlations, and multiple linear regressions. The results show that HF diets significantly increased final weight (p = 0.003) and visceral adipose tissue mass (p = 0.0002) compared to the control group. Olive oil induced significantly higher hepatic triglyceride accumulation (61.95 ± 27.26 mg/g, p = 0.0275), correlated with its richness in monounsaturated fatty acids (MUFAs), with a strong correlation between MUFAs in oils and their hepatic concentration (ρ = 0.678, p < 0.001). However, no significant effect was observed on plasma triglycerides, total cholesterol or HDL-C. These results suggest that the fatty acid composition of oils mainly influences hepatic metabolism without significantly altering blood lipids, probably due to powerful homeostatic mechanisms. The study highlights the need for a more nuanced nutritional approach, integrating the nature and stereospecificity of fatty acids according to the sn-2 hypothesis, as well as the presence of bioactive compounds that modulate gene expression. It paves the way for future research into the molecular mechanisms involved in lipid regulation and supports the development of personalised, mechanistically based dietary recommendations.