Fish oil and argan oil intake differently modulate insulin resistance and glucose intolerance in a rat model of dietary-induced obesity.
Recent studies have suggested that monounsaturated fatty acid (MUFA)-rich dietary fats do not have the same plasma cholesterol-lowering effects whereby rapeseed oil was more effective than olive oil. This phenomenon could be explicable by the content of other fatty acids or plant sterols. To further evaluate the effects of different MUFA-rich oils (18:1-rich sunflower oil, rapeseed oil, olive oil) in comparison to polyunsaturated (PUFA)-rich oils (18:2-rich sunflower oil) and saturated fat (palm stearin) on cholesterol and bile acid metabolism, male Syrian golden hamsters were fed semipurified diets containing 5% fat and 0.2% cholesterol for 5 weeks. To test whether oil refining would have an impact on the cholesterol-lowering potential, unrefined and refined varieties of rapeseed and olive oil were included. After 5 weeks, plasma total cholesterol (TC) was highest with palm stearin (10.0 +/- 2.6 mmol/l) while the MUFA- or PUFA-rich fats significantly lowered TC. The lowest TC concentrations were found with refined rapeseed, cold pressed rapeseed and 18:2-rich sunflower oil (6.7 +/- 1.2; 7.1 +/- 0.7 and 7.1 +/- 0.7 mmol/l, respectively), whereas TC was 10-15% higher (not significant) with 18:1-rich sunflower, virgin and refined olive oil. Liver cholesterol concentrations were lowest in hamsters fed palm stearin or 18:2-rich sunflower oil while MUFA-rich fats increased hepatic cholesteryl ester accumulation, especially of cholesteryl oleate. There were no significant differences in the fecal neutral sterol and bile acid excretion. These data demonstrate that MUFA-rich dietary fats, e.g. rapeseed, olive and 18:1-rich sunflower oil, are comparable in their hypocholesterolemic potential and cause similar effects on plasma cholesterol as 18:2-rich sunflower oil in hamsters when the dietary cholesterol intake is moderate.