Chemistry
Trans Fatty Acids
Trans fatty acids are unsaturated fatty acids that contain at least one trans double bond in their carbon chain. They are primarily formed during the process of hydrogenation of vegetable oils and are commonly found in partially hydrogenated oils. Trans fatty acids have been linked to negative health effects, including an increased risk of heart disease.
Written by Perlego with AI-assistance
Related key terms
1 of 5
10 Key excerpts on "Trans Fatty Acids"
eBook - PDF- Khetarpaul, Neelam(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Meaning of Trans Fat A type of fat created when oils are hydrogenated, which chemically transforms them from their normal liquid state (at room temperature) into solids. During the hydrogenation procedure extra hydrogen atoms are pumped into unsaturated fat, thereby creating Trans Fatty Acids. This process converts the mixture into a saturated fat, which obliterates its polyunsaturate benefits. Chemically speaking, trans fats are made of the same building blocks as non-trans fats, but are a slightly different shape. From a molecular perspective, the different shape is caused by double bonds between carbon atoms being in the trans rather than the cis configuration. Trans fats are more of a straight shape, while the cis shape is more kinked. This ebook is exclusively for this university only. Cannot be resold/distributed. Trans Fatty Acids can be found in a wide array of processed foods including cookies and margarines. Any food with “hydrogenated oils” or “partially hydrogenated oils” on the label contains Trans Fatty Acids. Some researchers believe such foods may actually be more damaging than regular saturated fats to those watching their cholesterol, saying Trans Fatty Acids decrease the good (HDL) cholesterol and increase the bad LDLs. Other scientists argue that the evidence is inconclusive and that Trans Fatty Acids are no worse than butter. In either case, it would seem that “moderation” is the watchword when consuming foods containing Trans Fatty Acids. At the turn of the century, a dramatic change in the fatty acid composition of the food supply of industrialized countries occurred when a process was discovered to convert liquid oils into solid or semisolid fats. In this process, known as partial hydrogenation, oils are heated in the presence of nickel or other metal catalysts and exposed to hydrogen gas.
eBook - PDF- Casimir C. Akoh(Author)
- 2005(Publication Date)
- CRC Press(Publisher)
245 10.7 Trans -Free Lipids ....................................................................................... 247 10.8 Conclusions ................................................................................................ 252 References .............................................................................................................. 252 10.1 INTRODUCTION In recent years, Trans Fatty Acids, more commonly known as trans fats, have been gaining a lot of interest from the scientific and health professional communities primarily because of the potential role of Trans Fatty Acids on cardiovascular disease risk. Publications on the adverse effects of Trans Fatty Acids on coronary heart disease, low-density and high-density lipoprotein cholesterols, and blood lipid levels are extensive. In a 1994 report, it was estimated that approximately 30,000 annual deaths from premature coronary heart disease could be linked to the consumption of Trans Fatty Acids [1]. Since then, more metabolic and epidemiologic studies have been reported. Due to the increasing evidence of the effects of Trans Fatty Acids on public health, the U.S. Food and Drug Administration (FDA) has recently published a final rule on the labeling of Trans Fatty Acids in food items. 204 Handbook of Functional Lipids 10.2 CHEMICAL STRUCTURE Fatty acid isomers are classified into two types, positional and geometric isomers. Positional isomers are formed when double bonds of the fatty acid molecule shift from their original position to other positions in the molecule. For example, fatty acids having double bonds at the ∆ 9 and ∆ 12 positions have been reported to shift to isomeric forms ranging from positions ∆ 4 to ∆ 16 [2], with the majority clustered in the vicinity of the original double bond [3–6]. Geometric isomers of unsaturated fatty acids are categorized into two forms: cis ( c ) and trans ( t ), as shown in Figure 10.1.
eBook - ePub- Dharma R. Kodali(Author)
- 2014(Publication Date)
- Academic Press and AOCS Press(Publisher)
4Nutritional Aspects of Trans Fatty Acids
Ingeborg A. Brouwer, Department of Health Sciences and the EMGO Institute for Health Care Research, Faculty of Earth and Life Sciences, VU University, Amsterdam, The NetherlandsAnne J. Wanders, Division of Human Nutrition, Wageningen University, Wageningen, The NetherlandsIntroduction
Most naturally occurring unsaturated fatty acids have their double bonds in the cis configuration. This cis configuration makes the molecule bend at the place of that double bond. Trans fatty acids (TFAs) are unsaturated fatty acids with at least one double bond in the trans configuration instead of the cis configuration. The double bond in the trans configuration gives the molecule a straighter shape. The straighter shape of the molecules allows them to pack better in solid state. This leads to transformation of oils into semisolid fats (Figure 4.1 ). There are two sources of TFAs: industrial and ruminant. In this chapter we look at the nutritional aspects of TFAs from various sources. We will only discuss studies in human subjects.Figure 4.1 Structures of cis - and trans fatty acids.Adapted from Brouwer, Wanders et al. (2010) .Elaidic acid (9-trans -C18:1) is a typical industrial TFA, produced by partial hydrogenation of vegetable oil. Vaccenic acid (11-trans -C18:1) is the predominant TFA in milk and meat from ruminant animals, although small amounts are also found in industrially hydrogenated fats. The 9,11 isomer of conjugated linoleic acid, or CLA (9-cis , 11-trans -C18:2), is found almost exclusively in ruminant fat; industrial production of CLA yields a mixture of 9,11 and 10,12 isomers. Oleic acid (9-cis -C18:1) is the predominant cis -unsaturated fatty acid in the diet. The location of the trans bond(s) in trans isomers of α-linolenic acid is not known precisely; for this figure it has been assigned arbitrarily to the 12 or omega-6 location. The same holds for the trans bonds in the trans
- Ching Kuang Chow(Author)
- 2007(Publication Date)
- CRC Press(Publisher)
II. OCCURRENCE OF Trans Fatty Acids IN THE U.S. FOOD SUPPLY Unsaturated fatty acids in foods can exist in either the cis or trans conguration (Figure 31.1). In the cis form, the hydrogen atoms are on the same side of the double bond. In the trans form they are opposite. As a result of these orientations around the double bond, the cis fatty acid has a bend in the carbon chain, whereas the trans fatty acid has a straight carbon chain resembling that of a saturated fatty acid. The term “positional isomer” is commonly used to refer to cis or Trans Fatty Acids if one or more of the double bonds has migrated to a new position in the fatty acid chain. Trans Fatty Acids (with double bonds at various positions in the fatty acid chain) and cis positional isomers are formed during partial hydrogenation of fats and oils, a process used to impart desirable stability and physical properties to food products such as margarines and spreads, shortenings, frying fats, and specialty fats (e.g., for llings, toppings, and candy). In addition, small amounts of Trans Fatty Acids occur naturally in foods such as milk, butter, and tallow as a result of biohydrogenation in ruminants. Widespread use of partially hydrogenated vegetable oils in the United States during the past four or ve decades has raised questions about the health effects resulting from the consumption of Trans Fatty Acids present in these products. Among isomeric fatty acids, interest has focused on Trans Fatty Acids rather than on positional isomers of cis fatty acids. Accordingly, this chapter deals with effects of Trans Fatty Acids rather than positional isomers of cis fatty acids. Typical levels of Trans Fatty Acids in food products containing partially hydrogenated oils are shown in Table 31.1. Frying oils used by restaurants and food service operations range in trans fatty acid content from 0% to about 35% of total fatty acids.
eBook - PDF- Dharma R. Kodali, Gary R. List(Authors)
- 2019(Publication Date)
- AOCS Publishing(Publisher)
Chapter 3 Nutritional Considerations of Trans Fatty Acids 1 J. Edward Hunter Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH 45221-0172; [email protected] Introduction In recent years, Trans Fatty Acids (TFA) in foods have received a lot of attention, both in the scientific literature and in the popular press. This attention has come largely from reports that high levels of TFA in the diet, compared to high levels of cis fatty acids, have resulted in unfavorable effects on both LDL-cholesterol, the so-called bad cholesterol, and HDL-cholesterol, the good cholesterol. In response to these reports, many health professional organizations have recommended reduced con-sumption of foods containing TFA, and in July 2003, the U.S. Food and Drug Administration (FDA) issued regulations requiring the labeling of TFA on packaged foods on or before January 1, 2006. In addition, many food manufacturers who have used partially hydrogenated oils in their products have developed or are considering ways to reduce or eliminate TFA from these products. This chapter will cover the following topics: (i) the occurrence of TFA in the U.S. food supply; (ii) three controlled dietary trials relevant to effects of dietary TFA on blood lipid parameters; (iii) a collective look at these and other clinical tri-als; and (iv) dietary recommendations regarding trans and saturated fatty acids by various health professional organizations. The focus will be on TFA in relation to coronary heart disease (CHD) because most of the recent literature on TFA con-cerns this area of interest. Figure 3.1 compares structural formulas of the cis fatty acid, oleic acid, with its trans isomer, elaidic acid. In the cis form, the hydrogen atoms are on the same side of the double bond.
eBook - PDFThe Cardiovascular System
Physiology, Diagnostics and Clinical Implications
- David C. Gaze(Author)
- 2012(Publication Date)
- IntechOpen(Publisher)
Formation of these trans double bonds thus impacts on the physical properties of a fatty acid. Fatty acids that contain a trans double bond have the potential for closer packing and alignment of their acyl chains, which will result in decreased molecular mobility (Willett, 2006). Therefore, the oil fluidity will be reduced when compared to that of fatty acids that contain a cis double bond. Partial hydrogenation of unsaturated oils results in the isomerisation of some of the remaining double bonds and the migration of others, producing an increase in the TFA content and a hardening of the fat. It has been shown that foods that contain hydrogenated oils tend to have a higher TFA content than those that do not contain hydrogenated oils (Moss, 2006; Oomen et al., 2001). Nevertheless, the hydrogenation of oils, such as corn oil, can result in both cis and trans double bonds, which are generally located anywhere between carbon 4 and carbon 16 of the fatty acids. One of the major TFAs is elaidic acid ( trans -9 C18:1), although during hydrogenation of polyunsaturated fatty acids (PUFAs), small amounts of several other TFAs are produced, including: trans -9, cis -12 C18:2; cis -9, trans -12 C18:2; cis -9, cis -12, trans -15 C18:3; and cis -5, cis -8, cis -11, cis -14, trans -17 C20:5 (Craig-Schmidt, 2006; Wagner et al., 2008). Conversely, one way to produce ‘zero’ levels of TFAs is through the trans -esterification reaction between vegetable oils and solid fatty acids, like C8:0, C12:0, C14:0 and C16:0. Correlations between high intake of industrially produced TFAs (IP-TFAs) and increased risk of coronary heart disease (CHD) have been reported (Stender et al., 2006; Tarrago-Trani Trans Fatty Acids and Human Health 45 et al., 2006), and lowering the intake of TFAs can also reduce the incidence of CHD (Willett, 2006).
eBook - PDF- J H P Tyman(Author)
- 1999(Publication Date)
- Woodhead Publishing(Publisher)
3 Trans Unsaturated Fat in Health and Disease David Kritchevsky THE WISTAR INSTITUTE, 3601 SPRUCE STREET, PHILADELPHIA, PA 19104, USA 1 Introduction In most naturally occurring unsaturated fats the double bonds are in the cis configuration. However, trans double bonds do occur naturally in a number of plants,' in the body fat of ruminants, and in milk. The major trans fatty acid of milk and beef fat is vaccenic acid (1 lt-18:l). The principal source of trans fat in the diet of the developed world is as a component of partially hydrogenated fat. Partial hydrogenation of vegetable or marine oils yields fats with greater stability, which can be used directly as margarines, salad oils, cooking oils and shortenings or used in the preparation of other foods. Heat treatment or frying of vegetable oils also yields some fatty acids containing trans unsaturated double bonds but the yields are quite Deodorization of oils may also yield a very small amount of trans fat.' Commercial hydrogenation of vegetable oils results in mostly monoenoic fats and most of the component trans-unsaturated (trans) fatty acids are present in the monoenoic fraction. The proportion of trans fats can be reduced by altering conditions of hydrogenation. In the course of the hydrogenation process the double bonds may also migrate along the hydrocarbon chain, yielding monoene fatty acids with double bonds anywhere from carbon 4 to carbon 16 (Table 1).6 Few biological studies which have been carried out using trans fats have used specific positional isomers (usually elaidic acid); insofar as the rest are concerned we must still clear up the possibility that the results may be due to specific positional isomers. The presence of a cis double bond in a fatty acid confers a bend to the acyl chain resulting in a flexible molecule. Fatty acids containing trans double bonds are linear because the angle conferred by the double bond is much smaller than that seen in cis fatty acids.
eBook - PDF- (Author)
- 2009(Publication Date)
- Academic Press(Publisher)
A report from the British Nutrition Foundation (BNF) in 1995 highlighted concerns over the varia-tions in estimations of trans fatty acid concentra-tions in some food products provided by different analytical techniques. A thorough review of the available analytical techniques was called for. cis configuration trans confi g uration H CH 3 C C (CH 2 ) x (CH 2 ) y COOH H H H CH 3 C C (CH 2 ) x (CH 2 ) y COOH Figure 1 The trans and cis configurations of unsaturated bonds. Reproduced with kind permission of the British Nutrition Foundation. cis conformation CH 3 CH CH HOOC (CH 2 ) y (CH 2 ) x trans conformation CH 3 CH HC COOH (CH 2 ) y (CH 2 ) x Figure 2 Conformation of the carbon chain with trans and cis bonds. Reproduced with kind permission of the British Nutrition Foundation. FATTY ACIDS / Trans Fatty Acids 195 Sources and Intakes The main sources of Trans Fatty Acids in the UK diet are cereal-based products (providing 27% of total trans fatty acid intake), margarines, spreads, and frying oils (22%), meat and meat products (18%), and milk, butter, and cheese (16%). In the USA, the main sources of intake are baked goods (28%), fried foods (25%), margarine, spreads, and shortenings (25%), savory snacks (10%), and milk and butter (9%). Typical ranges of Trans Fatty Acids in foods are shown in Table 2 . Trans isomers of C 18:1 (elaidic acid) are the most common Trans Fatty Acids, accounting for 65% of the total Trans Fatty Acids in the UK diet. Intakes of Trans Fatty Acids are difficult to assess because of: analytical inaccuracies; difficulties of obtaining reliable information about food intake. A number of countries have attempted to assess intakes of Trans Fatty Acids ( Table 3 ). Reliable intake data are available for the UK, based on a 7-day weighed intake of foods eaten both inside and out-side the home, for 2000 adults aged 16–64 years ( Table 3 ).
eBook - PDFFood Safety Chemistry
Toxicant Occurrence, Analysis and Mitigation
- Liangli (Lucy) Yu, Shuo Wang, Bao-Guo Sun, Liangli (Lucy) Yu, Shuo Wang, Bao-Guo Sun(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
133 Trans Fatty Acids Hongyan Li, Casimir C. Akoh, Jing Li, Huan Rao, and Zeyuan Deng 8.1 INTRODUCTION Saturated fatty acids (SFA) are solid at room temperature. Unsaturated fatty acids in nature are less tightly packed because of the cis configuration of the double bonds and they, generally, are liquids or oils at room temperature (Risérus, 2006). Trans Fatty Acids (TFA) consist of at least one isolated, nonconjugated, double bond in the trans geometric configuration. However, it excludes conjugated fatty acids such as 8 CONTENTS 8.1 Introduction .................................................................................................. 133 8.2 Formation and Occurrence ........................................................................... 135 8.2.1 Hydrogenation of Oils ....................................................................... 135 8.2.2 Natural Digestion of Ruminant Animals .......................................... 137 8.2.3 Levels of Trans Fatty Acids in Foods ............................................... 137 8.3 Analytical Methods ...................................................................................... 139 8.3.1 Sample Preparation and Extraction .................................................. 139 8.3.2 Gas Chromatography ........................................................................ 140 8.3.3 Silver Ion Chromatography ............................................................... 140 8.3.4 Fourier Transform Infrared Spectroscopy ........................................ 141 8.3.5 Capillary Electrophoresis ................................................................. 141 8.4 Evidence of Health Implications ................................................................... 142 8.4.1 Cardiovascular Health ...................................................................... 142 8.4.1.1 Lipid Effects .......................................................................
- Fereidoon Shahidi(Author)
- 2006(Publication Date)
- CRC Press(Publisher)
suggest that current levels of trans acids consumption are harmful. The coalition included the American Dietetic Association, the Society for Clinical Nutrition, and the Institute of Food Technologists 11 . Indeed, such opposition was based upon sound science reached by a distinguished panel of scientists. Published in the Journal of Clinical Nutrition 12 , the panel concluded, in part, “Data supporting a link between trans fatty acid intake and coronary heart disease (CHD) are equiv-ocal compared with extensive data from epidemiologic observation and animal and human studies that support a direct effect of saturated fat intake on CHD risk.” In addition, they concluded that, “Additional research is needed to adequately determine whether Trans Fatty Acids independently affect plasma lipoprotein cholesterol concentrations. Studies are needed to explore mechanisms and dose-response issues in experimental animals that have lipoprotein responses similar to those in humans, such as hamsters, non-human primates and pigs. Human metabolic studies are needed to better assess effects of Trans Fatty Acids on serum lipid concentrations and CHD risk.” Another task force concluded, “Compared with saturated acids, the issue of TFA is less signifi-cant because U.S. diets provide a smaller proportion of TFA and the data on their biological effects are limited. The debate about TFA should not detract from the body of scientific evidence linking the intake of saturated acids to cardiovascular risk, thereby providing the basis for dietary recommenda-tions limiting the intake of saturated fat. It is perhaps premature to make new dietary recommenda-tions for the population at large or to change nutrition policy (such as nutrition labeling) to mandate that TFA be listed separately or be included with saturated fatty acids on nutrition labels, especially in view of the inadequate data base for making or implementing such a change” 13 .
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
