trans- and Positional Isomers of Common Fatty Acids

Dietary trans FA at sufficiently high levels have been found to increase low density lipoprotein (LDL)-cholesterol and decrease high density lipoprotein (HDL)-cholesterol (and thus to increase the ratio of LDL-cholesterol/HDL-cholesterol) compared with diets high in cis monounsaturated FA or PUFA. The dietary levels of trans FA at which these effects are easily measured are around 4% of energy or higher to increase LDL-cholesterol and around 5 to 6% of energy or higher to decrease HDL-cholesterol, compared with essentially trans-free control diets. Very limited data at lower levels of intake (less than 4% of energy) are available. Most health professional organizations and some governments now recommend reduced consumption of foods containing trans FA, and effective January 1, 2006, the U.S. Food and Drug Administration requires the labeling of the amounts of trans FA per serving in packaged foods. In response, the food industry is working on ways to eliminate or greatly reduce trans FA in food products. Current efforts focus on four technological options: (i) modification of the hydrogenation process, (ii) use of interesterification, (iii) use of fractions high in solids from natural oils, and (iv) use of trait-enhanced oils. Challenges to the food industry in replacing trans FA in foods are to develop formulation options that provide equivalent functionality, are economically feasible, and do not greatly increase saturated FA content.

Section: Review Articles (I) Reviews Of Studies Reported Prior To 1990mentioning

confidence: 99%

Dietarytransfatty acids: Review of recent human studies and food industry responses

Hunter

2006

“…The incorporation of dietary trans fatty acids, particularly of elaidic acid, in organ lipids has been studied extensively (4)(5)(6)(7)(8)(9)(10)(11)(12)14,(22)(23)(24)(25)(26)(27)(28)(29)(30). Our results are in agreement with the general findings that most trans octadecenoic acids, including elaidic acid, readily incorporate into organ TG and in the 1-position of phosphoglycerides, where they substitute for saturated fatty acids.…”

Section: Discussionmentioning

confidence: 99%

“…During the process of hydrogenation used to produce hardened fat, the unsaturated fatty acids are isomerized, yielding a mixture of geometric (cis and trans) and positional isomers (1)(2)(3). The effects of isomeric fatty acids on the essential fatty acid (EFA) status of experimental animals and on the metabolism of EFA were the focus of nutritional research (4)(5)(6)(7)(8)(9)(10)(11)(12). In these works, linoleic acid and/or its metabolites were extensively studied.…”

Section: Pierre-olivier Astorg* and Jo~lle Chevaliermentioning

confidence: 99%

Polyunsaturated fatty acids in tissues of rats fed trielaidin and high or low levels of linolenic acid

Astorg

Chevalier

1987

Male and female weanling rats that were born to dams fed a diet low in linolenic acid received diets of 15% lipids by weight containing 45% elaidic acid (as trielaidin) and 8.5% or 0.1% linolenic acid for 10 weeks. Four other groups, in which palmitic or oleic acid replaced elaidic acid in the diet, served as controls. The fatty acid profiles of several lipid classes were determined in adipose tissue, adrenals, testes, heart and brain. Elaidic acid was incorporated into tissue lipids in varying degrees, depending on the organ and on the lipid class. Feeding elaidic acid induced no changes in the polyunsaturated fatty acid (PUFA) profiles of testes lipids but resulted in definite modifications of the PUFA patterns of heart phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In linolenic acid-deprived rats, arachidonic acid was decreased in PC and linoleic acid was increased in both PC and PE; 22:5n-6 was strongly depressed in both PC and PE. In linolenic acid-fed rats, 22:6n-3 was decreased in PC and PE. These changes, on the whole, were more evident in females, and some also were observed in adrenal cholesteryl esters but only slightly in brain phospholipids. The apparent inhibition of the biosynthesis of PUFA induced by dietary elaidic acid appeared to be complex and of greater intensity in the n-6 fatty acid series than in their n-3 homologues.

“…However, this chemical process forms variable and, under some conditions, high amounts of positional and/or geometric trans fatty acids isomers (10). The biological effects of trans fatty acids have been a matter of controversy (11,12), and concerns about their consumption and biological effects arose from the "unnatural" origin of these isomeric fatty acids (13). Partially hydrogenated fish oil (PHFO) and highly hydrogenated fish oil (HHFO) are widely used in some South American and European countries for the manufacture of cheap margarines and industrial fats, and as components of diverse food items.…”

mentioning

confidence: 99%

Effect of the degree of hydrogenation of dietary fish oil on the trans fatty acid content and enzymatic activity of rat hepatic microsomes

Morgado

Galleguillos

Sanhueza

et al. 1998

The degree of fat hydrogenation and the trans fatty acid content of the diet affect the fatty acid composition of membranes, and the amount and the activity of some membrane enzymes. We describe the effects of four isocaloric diets containing either sunflower oil (SO, 0% trans), fish oil (FO, 0.5% trans), partially hydrogenated fish oil (PHFO, 30% trans), or highly hydrogenated fish oil (HHFO, 3.6% trans) as fat sources on the lipid composition and the trans fatty acid content of rat hepatic microsomes. We also describe the effect of these diets on the cytochrome P-450 content and on the aminopyrine N-demethylase, aniline hydroxylase, and UDP-glucuronyl transferase microsomal activities. Cytochrome P-450 content was dependent on the degree of unsaturation of the diet, being higher for the FO-containing diet and lower for the HHFO diet. Aminopyrine N-demethylase activity also correlated with the degree of unsaturation of the diet as did the cytochrome P-450 content did (FO > SO > PHFO > HHFO). Aniline hydroxylase activity appeared to be independent of the degree of unsaturation of the dietary fat, but correlated with the trans fatty acid content of the diet, which was also reflected in the trans content of the microsomal membranes. UDP-glucuronyl transferase activity was higher for the FO-containing diet than for the SO diet, showing intermediate values after the PHFO and HHFO diets.