Chylomicrons fatty acid compositions

The effects of Caprenin, another structured lipid, on chylomicron fatty acid composition and postprandial semm lipid concentrations have also been studied (178). It was found that there is a very low uptake of C8 0, C10 0, and C22 0 into chylomicrons. Moreover, a postprandial lipemia after caprenin is comparable with that produced by other dietary fats as opposed to a fat-free meal. There is considerable... 

Fat constitutes approximately 38% of the calories in the average North American diet. Of this, more than 95% of the calories are present as triacylglycerols (3 fatty acids esterified to a glycerol backbone). During ingestion and absorption, dietary triacylglycerols are broken down into their constituents and then reassembled for transport to adipose tissue in chylomicrons (see Chapter 2). Thus, the fatty acid composition of adipose triacylglycerols varies with the type of food consumed. 

Murata, M., Hara, K., and Ide, T. (1994) Alteration by Diacyl-glycerols of the Transport and Fatty Acid Composition of Lymph Chylomicrons in Rats, Biosci. Biotech. Biochem. 58, 1416 1419. 

Bragdon, j. H., and A. EIarmen The fatty acid composition of chylomicrons of chyle and serum following the ingestion of different oils. J. Lipid Res. 1, 167—170 (1960). 

There were no differences in the overall fatty acid composition of chylomicron... 

TAG between the rats receiving the TAG and DAG emulsions. However, considerable differences were observed in the fatty acid composition at the 2-position of TAG between the two groups of rats. Thus, intragastric infusion with DAG (mainly consisting of 1,3-DAG) instead of TAG not only altered the rate of lipid transport by lymph chylomicrons but also altered the structure of the chylomicron TAG molecules. These results indicate that the relative contributions of the 2-MAG pathway and the glycerol-3-phosphate pathway to TAG re-esterification may vary depending on the types of acylglycerols in the diet. 

The major forms of vitamin A (apart from carotene) are the esters of retinol with long chain fatty acids. Compared with the normal pattern of fatty acids in tissue lipids, they are a relatively select group and much more saturated. Palmitic acid predominates, together with smaller quantities of stearic and oleic acids. When the esters reach the lumen of the small intestine, they are almost completely hydrolysed, absorbed into the intestinal cells and reesterified. They are transported as components of the chylomicrons to the liver where they are stored almost entirely as retinyl palmitate, regardless of the composition of the dietary esters. Modification of dietary retinyl esters to such a specific fatty acid composition requires, as in the case of the cholesterol esters, specific hydrolytic and synthetic enzymes. These occur mainly in the liver, intestine and the retina of the eye. 

It is now accepted that increased postprandial lipemia is directly related to an increased rate of progression of atherosclerosis and increased risk of CHD (50,51). The degree of postprandial hypertriglyceridemia in patients with CHD is due to impaired TG clearance after a standardized fatty meal (52). Exaggerated lipemia is common in patients with CHD, and peak lipemia may occur 8 h after the fatty meal instead of the usual 3 h. Postprandial lipemia promotes the formation of chylomicron remnants (52,53). Indeed, a diet low in fat, in particular saturated fat, reduces the levels of chylomicron remnants in humans (54). The composition of the fatty meal is also important, and fish oil fatty acids may be less Upemic (54,55). 

Yli-Jokipii, K.M., Schwab, U.S., Tahvonen, R.L., Kurvinen, J.P, Mykkanen, H.M. and Kallio, H.P., Triacylglycerol molecular weight and to a lesser extent, fatty acid positional distribution, affect chylomicron triacylglycerol composition in women. J. Nutr, 132, 924—929 (2002). 

Yang, LY and Kuksis, A (1987) Size and composition of lymph chylomicrons following feeding com oil or its fatty acid methyl esters. Biochem. Cell. Biol, 65, 514-524. 

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