Trans Fatty acids digestion

Loor, J.J., Ueda, K., Ferlay, A., Chilliard, Y., and Doreau, M. 2005. Intestinal flow and digestibility of trans fatty acids and conjugated linoleic acids (CLA) in dairy cows fed a high-concentrate diet supplemented with fish oil, linseed oil, or sunflower oil. Anim. Feed Sci. Tech. 119, 203-225. 

Bauman, D.E., Lock A.L., Corl B.A., IpC., Salter A.M., Parodi P.W. 2005. Milk fatty acids and human health potential role of conjugated linoleic acid and trans fatty acids. In Ruminant Physiology Digestion, Metabolism and Impact of Nutrition on Gene Expression, Immunology and Stress. (K. Sejrsen, T. Hvelplund, and M.O. Nielsen, eds.), pp. 523-555, Wageningen Academic Publishers, Wageningen, The Netherlands. Academic Publishers. 

Trans fatty acids are present in the diet in esterified form, mainly in triacylglycerols but those from ruminant sources may also be present in phospholipids. Before absorption into the body, triacylglycerols must be digested by pancreatic lipase in the upper small intestine. There is no evidence of differences in the hydrolysis and absorption of trans fatty acids, in comparison with that of cis fatty acids. Trans fatty acids are transported from the intestine mainly in chylomicrons, but some are also incorporated into cholesteryl esters and phospholipids. 

D.T. Hill, S.A. Cobbs, and J.P. Bolte. Using volatile fatty acid relationships to predict anaerobic digester failure. Trans. ASAE, 30 496-501, 1987. 

This step leaves two cleavage products. The first, derived from the two carbons at the carboxyl end of the fatty acid, is acetyl-CoA, which can be further metabolized in the TCA cycle. The second cleavage product is a shorter fatty acyl-CoA. Thus, for example, the initial step of digesting a fatty acid with 16 carbons is an acyl-CoA molecule where the acyl group has 14 carbons and a molecule of acetyl-CoA. The P-oxidation scheme may be used to accommodate unsaturated fatty acids also. The reactions occur as described previously for the saturated portions of the molecule. Where a trans carbon-carbon double bond occurs between the %- and p-carbons of the acyl-CoA, the accommodation is fairly simple reaction 1 isn t needed. Where the double bonds are in the cis configuration, or are between the P and y carbons, isomerase enzymes change the location of the double bonds to make recognizable substrates for P-oxidation. 

Keeney M (1970) Lipid metabohsm in the rumen. In PhUlipson AT (ed) Physiology of digestion and metabolism in the ruminant. Oriel Press, Newcastle, pp 489-503 Kemp P, Lander DJ (1984) Hydrogenation in vitro of a-hnolenic add to stearic acid by mixed cultures of pure strains of rumen bacteria. J Gen Microbiol 130 527-533 Kemp P, White RW, Lander DJ (1975) The hydrogenation of unsaturated fatty adds by five bacterial isolates from the sheep rumen, including a new spedes. J Gen Microbiol 90 100-114 Kepler CR, Tove SB (1967) Biohydrogenation of unsaturated fatty acids III. Purification trans-isomerase from Butyrivibrio fibrisolvens. J Biol Chem 242 5686-5692... 

An increased content of trans-unsaturated fatty acids is also found in some other mammals (such as kangaroos) where herbage is pre-digested by microorganisms in their digestive tract. Trans-unsaturated fatty acids partly pass into the milk (the predominant acid is vaccenic acid, but also present are elaidic acid, 3-5, and some other fatty acids). These fatty acids are ingested by humans as a part of their food and therefore occur in human depot fat and in breast milk. 

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