Effects of dietary fish oil on the fatty acid composition of the main lipid classes of chick plasma lipoproteins.

We have studied the effects of diet supplementation with 10% fish oil on fatty acid composition of the main lipid classes of chick plasma lipoproteins bearing in mind the relationship between platelet aggregation and eicosanoid production from arachidonic acid. Fish oil drastically increased the percentages of 20:5 n-3 and 22:6 n-3 acids in the high density lipoprotein lipids. The 20:5/22:6 ratio increased in triacylglycerol fraction whereas in phospholipids and cholesterol esters both 20:5 and 22:6 acids increased in a similar proportion. The percentage of arachidonic acid was higher in phospholipids than in the other lipid classes from this lipoprotein fraction and was significantly reduced by fish oil feeding. Linoleic acid, which was the most abundant fatty acid in cholesterol esters, strongly decreased after fish oil consumption. Changes induced in low- and very low density lipoproteins were similar to that observed in the high density lipoproteins. However, in the very low density lipoproteins, the 20:5/22:6 ratio was not increased in triacylglycerols, in contrast to that found in the high- and low density fractions. Our results suggest that decreases observed by fish oil feeding in the percentages of arachidonic acid in phospholipids and linoleic acid in cholesterol esters in the three lipoprotein fractions may be of importance to explain some pharmacological effects of n-3 PUFA with regard to vascular diseases.