Effects of dietary fats on the fluidity of human high-density lipoprotein: influence of the overall composition and phospholipid fatty acids.

The present study was undertaken to analyze whether the changes induced by dietary manipulations in the chemical composition of HDL, particularly in total phospholipids, phosphatidylcholine and sphingomyelin fatty acid composition, modified their fluidity. 12 healthy women, aged 26-49 years were studied. They consumed, over periods of 5 weeks, various isocaloric diets, each containing 30% of the calories as fat. 15.6% of the total calories were provided successively by olive oil, soybean oil, corn oil, and milk fats. The HDL fluorescence anisotropy was measured with 1,6-diphenyl-1,3,5-hexatriene (DPH) by fluorescence polarization. The HDL from the monounsaturated diet, olive oil, were the most fluid particles. The HDL fluorescence anisotropy was positively correlated with their free cholesterol percentage and negatively correlated with their triacylglycerol content and their triacylglycerol/phospholipid ratio. Moreover, the HDL fluorescence anisotropy was negatively correlated with the percentage of oleic acid in their total phospholipids and particularly in the phosphatidylcholine. These results suggest that the percentages of triacylglycerol and oleic acid in phospholipids of HDL have a fluidifying effect on these lipoproteins.