Olive oil increases the hepatic triacylglycerol content in mice by a distinct influence on the synthesis and oxidation of fatty acids

Diet supplementation with olive oil exerts beneficial effects on an organism, even if an increase in the level of hepatic lipids has been concomitantly observed. This study was therefore designed to investigate whether the stimulation of lipogenesis was responsible for the olive oil-induced hepatic fat accumulation. In mice fed for 8 weeks with an olive oil-enriched diet, an increase of about 2.6 fold in the level of liver triglycerides was found in comparison to animals fed with a corn oil-containing diet. Despite that, no increase in the activities of cytosolic lipogenic enzymes or of the mitochondrial tricarboxylate carrier was found; on the contrary, a decrease in the activity of carnitine palmitoyltransferase I was observed. This impairment of fatty acid oxidation, which was not apparent in corn oil-fed animals, may have had a role in the increase of hepatic lipid content found in the olive oil-fed mice. A conclusive finding from this study is that the different effects of the two dietary oils on the hepatic lipid metabolism in mice can be attributed to their specific fatty acid composition. In fact, olive oil, as has been previously reported, contains more oleic acid in comparison to corn oil which, on the contrary, is rich in linoleic acid. The present data, therefore, reinforce the current view of fatty acids as being powerful and versatile modulators of lipid metabolism.