Lipoprotein trans fatty acids

Catalytic hydrogenation of vegetable oils is widely used to form harder fats and to decrease the content of polyunsaturated fatty acyl groups. The products have a greatly increased resistance to rancidity. However, they also contain fats with trans double bonds as well as isomers with double bonds in unusual positions.251 253 Such compounds may interfere with normal fatty acid metabolism and also appear to affect serum lipoprotein levels adversely. Trans fatty acids are present in some foods. One hundred grams of butter contain 4-8 g, but hydrogenated fats often contain much more. It has been estimated that in the United States trans fatty acids account for 6-8% of total dietary fat.253... 

Aro, A., Jauhianinen, M., Partanen, R., Salminen, I., and Mutanen, M. (1997). Stearic acid, trans fatty acids, and dairy fat Effects on serum and lipoprotein lipids, apolipoproteins, lipoprotein(a), and lipid transfer proteins in healthy subjects. Am.. Clin. Nutr. 65, 1419-1426. 

Katan, M. B., Zock, P. L., and Mensink, R. P. (1995b). Trans fatty acids and their effects on lipoproteins in humans. Annu. Rev. Nutr. 15, 473-493. 

Judd, J.T., Clevidence, B.A., Muesing, R.A., Wittes, J., Sunkin, M.E. and Podczasy, J. (1994) Dietary trans fatty acids Effects on plasma lipids and lipoproteins of healthy men and women. Am. J. Clin. Nutr., 59, 861-868. 

Mensink, R.P. M.B. Katan. Effects of dietary trans fatty acids on high-density and low-density lipoprotein cholesterol levels in healthy subjects. N. Engl. J. Med. 1990,323, 439—445. 

Fatty acids affect CHD risk, in part, via effects on plasma lipids and lipoproteins. A meta-analysis of 60 controlled trials (Mensink et al., 2003) reported that saturated and trans fatty acids increase low-density lipoprotein cholesterol (LDL-C), whereas unsaturated fatty acids decrease LDL-C. Saturated fatty acids, MUFA, and PUFA all increase high-density lipoprotein cholesterol (HDL-C), whereas trans fatty acids do not. Both MUFA and PUFA decrease the TC to HDL-C ratio, whereas trans fatty acids increase it, and SFA have little effect (Fig. 20.4). 

The adverse effects of trans fatty acids on serum lipids and lipoproteins are thought to be mediated by alterations in lipid catabolism and metabolism. Trans fatty acids increase the catabolism rates of apolipoprotein A-I and decrease apolipoprotein B catabolism rates (Matthan et al., 2004), reduce LDL-C particle size (Mauger et al., 2003), and can increase cholesteryl ester transfer protein (CETP) activity (van Tol et al., 1995). CETP mediates the transfer of cholesterol esters from HDL- to LDL- and very-low-density lipoprotein (VLDL)-C, thereby offering a potential explanation for the LDL-C-raising and HDL-C-lowering effect of trans fatty acids. 

Zock, P.L. M.B. Katan. Hydrogenation alternatives effects of trans fatty acids and stearic acid versus linoleic acid on serum lipids and lipoproteins in humans. J. Lipid Res. 1992, 33, 399-410. 

There is a confirmed relationship between the consumption of foods containing trans fatty acids and high-low-density lipoprotein (LDL)-cholesterol levels associated with increased risk of coronary heart disease, a leading cause of death in the United States and a growing concern in Europe. 

Unfortunately, not all of the unsaturated fats appear to be equally safe. When we eat partially hydrogenated fats, we increase our consumption of trans-fatty acids. These acids, which are isomers of the naturally occurring ds-fatty acids, have been implicated in a variety of conditions, including heart disease, cancer, and diabetes. The strongest evidence that frans-fatty acids may be harmful comes in studies of the incidence of coronary heart disease. Ingestion of trans-fatty acids appears to increase blood cholesterol levels, in particular the ratio of low-density lipoproteins (LDL, or "bad" cholesterol) to high-density lipoproteins (HDL, or "good" cholesterol). The trans-fatty acids appear to exhibit harmful effects on the heart that are similar to those shown by saturated fatty acids. 

Recent studies have shown that consuming a significant amount of trans fatty acids can lead to serious health problems related to serum cholesterol levels. Low overall serum cholesterol and a decreased ratio of low-density lipoprotein (LDL) cholesterol to high-density lipoprotein (HDL) cholesterol are associated with good overall cardiovascular health. High semm cholesterol and an elevated ratio of LDL cholesterol to HDL cholesterol are linked to a high incidence of cardiovascular disease, especially atherosclerosis. Research has indicated that diets high in either saturated fatty adds or trans fatty adds raise the ratio of serum LDL cholesterol to HDL cholesterol and substantially increase the risk of cardiovascular disease. 

The concern about trans fatty acids is that they behave like saturated fatty acids in the body. Several studies reported that trans fatty acids raise the levels of LDL-cholesterol, low-density lipoproteins containing cholesterol that can accumulate in the arteries. More research is still needed to determine the overall impact of trans fatty acids present in fats in our diets. Since 2006, food labels have given the grams of trans fat per serving. 

Effect of trans Fatty Acids on Plasma Lipoproteins... 

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