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PubMed1988

Trans fatty acid content of selected brands of West German nut-nougat cream.

The fatty acid composition including trans fatty acids of 12 brands of nut-nougat creams were analyzed by capillary gas chromatography. The creams consisted mainly of sugar and partially hydrogenated vegetable oil. The lipid content, which was quantified gravimetrically, amounted to between 30 and 38.2% in the different brands. The fatty acid composition varied considerably between the different creams. Linoleic acid, the major polyunsaturated fatty acid (PUFA), ranged from 12 to 39%. Palmitic acid (16:0), which was the main fatty acid, varied from 9 to 27%. The total trans fatty acid content of the 12 creams ranged from 0.9 to 12.3%. Only two of the creams contained less than 1% of trans fatty acids; 18:1t was the trans fatty acid found in the greatest amounts, whereas 16:1t and 14:1t were only found in trace amounts. Three samples had amounts of 18:2tt, 18:2ct, and 18:2tc between 0.7 and 1.06%; only small amounts of linoleate isomers were detected in the other creams. Our results show that trans fatty acids are present in every brand of chocolate cream tested. Since the potential risk of arteriosclerosis and cancer resulting from the consumption of trans fatty acids is not yet clear, different ways of production should be used in order to eliminate them from the creams that are a preferred bread spread of infants and children.

Cacao↗
PubMed2001

Trans fatty acids and cardiovascular risk.

Trans fatty acids are found in partially hydrogenated vegetable oil, in meats, and in dairy products. Their effect on blood cholesterol concentrations was examined decades ago, but recently there has been renewed interest in understanding how trans fatty acids affect blood lipids and lipoprotein cholesterol concentrations. Current advice to reduce cardiovascular disease (CVD) risk includes decreasing the consumption of saturated and total fat to help manage blood cholesterol concentrations. Saturated fat contributes significantly to total fat intake and markedly raises blood cholesterol concentrations. Trans fatty acids, which are consumed in much smaller quantities, have been shown to be modestly hypercholesterolemic in studies that have substituted hydrogenated vegetable oils for unhydrogenated oils. In contrast, when partially hydrogenated vegetable oils containing trans fatty acids are substituted for cholesterol-raising saturated fats, blood cholesterol levels are reduced. Partially hydrogenated vegetable oils are used in place of saturated fat in many food products. These foods can help consumers lower their saturated fat intake to achieve dietary recommendations. The following review critically examines the role of hydrogenated fats in the food supply, the metabolism of trans fatty acids, and the scientific literature surrounding the effects of partially hydrogenated vegetable oils and trans fatty acids on blood cholesterol concentrations and cardiovascular disease risk.

Cardiovascular Diseases↗
PubMed1995

Variation of trans fatty acids in milk fats.

Trans fatty acids are discussed in connection with an increased risk of atherosclerosis. Therefore, the development of a rapid and exact measuring method for the determination of trans fatty acids in milk fat is of great interest. Using gas chromatographic analysis of the trans-octadecenoic fatty acids as well as of the triglycerides of 100 different milk fat samples a formula consisting of different triglycerides for the quick determination of trans contents was developed by means of statistical methods (standard deviation = 0.293%, r = 0.9977). Subsequently, the seasonal variations of the trans contents in milk fat samples from a large milk collection area were determined using rapid triglyceride analyses. For the trans fatty acid contents of the 100 milk fat samples and the samples from the milk collection area scattering ranges of 1.91-6.34 wt% resp. 1.97-4.37 wt% were found; the mean contents were 3.83 and 3.18 wt%, and the median values 3.67 and 3.30 wt%, respectively.

Animals↗
PubMed1997

Evaluating acid and base catalysts in the methylation of milk and rumen fatty acids with special emphasis on conjugated dienes and total trans fatty acids.

Milk analysis is receiving increased attention. Milk contains conjugated octadecadienoic acids (18:2) purported to be anticarcinogenic, low levels of essential fatty acids, and trans fatty acids that increase when essential fatty acids are increased in dairy rations. Milk and rumen fatty acid methyl esters (FAME) were prepared using several acid- (HCl, BF3, acetyl chloride, H2SO4) or base-catalysts (NaOCH3, tetramethylguanidine, diazomethane), or combinations thereof. All acid-catalyzed procedures resulted in decreased cis/trans (delta 9c,11t-18:2) and increased trans/trans (delta 9t,11t-18:2) conjugated dienes and the production of allylic methoxy artifacts. The methoxy artifacts were identified by gas-liquid chromatography (Gl.C)-mass spectroscopy. The base-catalyzed procedures gave no isomerization of conjugated dienes and no methoxy artifacts, but they did not transesterify N-acyl lipids such as sphingomyelin, and NaOCH3 did not methylate free fatty acids. In addition, reaction with tetramethylguanidine coextracted material with hexane that interfered with the determination of the short-chain FAME by GLC. Acid-catalyzed methylation resulted in the loss of about 12% total conjugated dienes, 42% recovery of the delta 9c,11t-18:2 isomer, a fourfold increase in delta 9t,11t-18:2, and the formation of methoxy artifacts, compared with the base-catalyzed reactions. Total milk FAME showed significant infrared (IR) absorption due to conjugated dienes at 985 and 948 cm-1. The IR determination of total trans content of milk FAME was not fully satisfactory because the 966 cm-1 trans band overlapped with the conjugated diene bands. IR accuracy was limited by the fact that the absorptivity of methyl elaidate, used as calibration standard, was different from those of the other minor trans fatty acids (e.g., dienes) found in milk. In addition, acid-catalyzed reactions produced interfering material that absorbed extensively in the trans IR region. No single method or combination of methods could adequately prepare FAME from all lipid classes in milk or rumen lipids, and not affect the conjugated dienes. The best compromise for milk fatty acids was obtained with NaOCH3 followed by HCl or BF3, or diazomethane followed by NaOCH3, being aware that sphingomyelins are ignored. For rumen samples, the best method was diazomethane followed by NaOCH3.

Acetates↗
PubMed2006

The relation between trans fatty acid levels and increased risk of myocardial infarction does not hold at lower levels of trans fatty acids in the Costa Rican food supply.

Data on the effects of recent industrial modifications that reduced the trans fatty acid (TFA) content in food supplies are scarce. In this study, incident cases (n = 1797) of a first nonfatal myocardial infarction (MI) were matched with population controls (n = 1797) for age, sex, and area of residence in Costa Rica. Odds ratio (OR) and 95% CI were calculated from conditional logistic regressions before and after a reduction of TFA in Costa Rican foods. Initially, the median quintiles of total adipose tissue TFA were 1.85, 2.47, 2.99, 3.58, and 4.40 g/100 g; total TFA was positively associated with increased MI risk after adjusting for established risk factors (OR by quintiles of total TFA: 1.00, 1.37, 1.91, 1.86, 3.28; P for trend < 0.001). This association was mostly due to 18:2 trans. In contrast, after industrial modification, median quintiles of total adipose tissue TFA were 1.84, 2.26, 2.57, 2.88, and 3.42 g/100 g; the association with MI was no longer significant (OR by quintiles of total TFA: 1.00, 0.78, 1.03, 0.88, and 1.03; P for trend = 0.65). Adipose tissue 18:1 trans fatty acids were not associated with risk of MI before or after the modification. Although to date there are no TFA regulations in Costa Rica, it appears that indirect international influence has led to a TFA reduction in the food supply and, consequently, to a reduction in the risk of nonfatal MI. The public health sector of Costa Rica should regulate food labeling and content to ensure very low levels of TFA intake.

Adipose Tissue↗
PubMed2002

Microbial biohydrogenation of oleic acid to trans isomers in vitro.

Ruminant products are significant sources of dietary trans fatty acids. Trans fatty acids, including various conjugated linoleic acid isomers, have been shown to act as metabolic modifiers of lipid metabolism. Trans fatty acids originate from biohydrogenation of dietary unsaturated fatty acids by gut microbes; however, the exact synthetic pathways are unclear. It was our goal to examine the biohydrogenation pathway for oleic acid, where oleic acid is hydrogenated directly to stearic acid. Our objective in this study was to trace the time course of appearance of 13C in labeled oleic acid to determine if trans monoenes are formed from the 13C-labeled oleic acid or if the 13C appears only in stearic acid as described in reviews of earlier work. Enrichments were calculated from the mass abundance of 13C in major fatty acid fragments and expressed as a percentage of total carbon isotopomers. Significant 13C enrichment was found in stearic acid, oleic acid, trans-6, trans-7, and in all trans C18:1 in positions 9-16. We concluded that the biohydrogenation of oleic acid by mixed ruminal microbes involves the formation of several positional isomers of trans monoenes rather than only direct biohydrogenation to form stearic acid as previously described.

Animals↗
PubMed2000

Adipose tissue fatty acids and risk of myocardial infarction--a case-control study.

OBJECTIVES: To study the association between content in adipose tissue of very long-chain n-3 fatty acids, trans fatty acids, linoleic acid and alpha-linolenic acid and risk of a first myocardial infarction. DESIGN AND SUBJECTS: A case-control design among 100 patients and 98 population controls both men and postmenopausal women, age 45-75 y. Adipose tissue fatty acids were determined by gas-liquid chromatography. Intake data were obtained through interview using a validated food frequency questionnaire. RESULTS: Dietary intake and adipose tissue content of the fatty acids studied correlated significantly. Adipose tissue contents of eicosapentaenoic acid (20:5n-3), docosapentaenoic acid (22:5n-3) and docosahexaenoic acid (22:6n-3) were significantly lower while those of trans fatty acids, linoleic and alpha-linolenic acid were significantly higher in patients than in controls. Age and sex adjusted odds ratios (OR) were significantly reduced with increasing quintiles of very long-chain n-3 fatty acids, thus the OR in the fifth compared to the first quintile was 0.23 (95% CI 0.08-0.70). After further adjustment for waist-to-hip ratio, smoking, family history of CHD and content of trans fatty acids, the OR in the highest quintile was 0.17 (95% CI 0.04-0.76) and the P for trend 0. 016. Age and sex adjusted OR was increased in the fifth compared to the first quintile of trans fatty acids (OR 2.81, 95% CI 1.16-6.84), linoleic acid (OR 2.10, 95% CI 0.87-5.07) and alpha-linolenic acid (OR 1.96, 95% CI 0.83-4.61), and P for trend was 0.002, 0.005 and 0. 020, respectively. The trends remained significant after adjustment for waist-to-hip ratio, smoking, and family history of coronary heart disease. Trans fatty acids, linoleic acid and alpha-linolenic acid in adipose tissue were strongly correlated, indicating a common source, most likely margarine. When each of these fatty acid species were adjusted for the two others the trends were no longer significant. CONCLUSION: Intake of very long-chain n-3 fatty acids as reflected in adipose tissue content is inversely associated with risk of myocardial infarction. Trans fatty acids, linoleic and alpha-linolenic acid were intercorrelated and associated with increased risk. It is suggested that the increased risk may be connected to trans fatty acids or to some other factor associated with margarine consumption. European Journal of Clinical Nutrition 54, 618-625.

Adipose Tissue↗
PubMed1997

trans Fatty acids: infant and fetal development.

This review evaluates scientific data associated with the possibility that trans fatty acids compromise fetal and infant early development. Concerns have been triggered by research that has heightened our awareness of the importance of n-3 and n-6 fatty acids; shown that trans fatty acids inhibit delta6 desaturation of linoleic acid; identified trans fatty acid isomers in fetal, infant, and maternal tissues; and reported an inverse association between the trans fatty acid content of tissue lipids and measures of growth and development. Animal studies provide little evidence that trans fatty acids influence growth, reproduction, or gross aspects of fetal development. However, these models may not have been appropriate for addressing all the subtle effects that influence development of human infant retinal, neural, or brain function. Human studies are hampered by the complexity of the interrelations among nutritional, genetic, and environmental factors and by ethical considerations that constrain the research design. Existing data have not established a causal relation between trans fatty acid intake and early development. Conclusions cannot be drawn from the possible association found between trans fatty acid exposure and lower n-3 and n-6 long-chain polyunsaturated fatty acids and growth because of confounding factors. Few studies addressed the question of whether trans fatty acids adversely affect human fetal growth. One study reported a correlation between the trans fatty acid content of plasma and birth weight of preterm infants and one study reported a relation between preterm births and the trans fatty acid content of maternal plasma. Limited associative data have addressed whether trans fatty acids adversely affect fetal and infant neurodevelopment and growth. The interpretation of existing research and development of recommendations should be done cautiously. Suggestions for research to clarify these issues are made.

Child↗
PubMed1995

Do trans fatty acids impair linoleic acid metabolism in children?

Trans isomeric fatty acids disturb the metabolism of essential polyunsaturated fatty acids in animals and in premature infants. We assessed whether similar effects may also occur in healthy children. Plasma phospholipid fatty acid composition was analysed in 53 apparently healthy children aged 1-15 years (mean 7.5 years). Trans fatty acids were found in all samples and contributed 1.78 +/- 0.10% (w/w, mean +/- SEM). There was no relation of the major trans isomer octadecenoic acid and of total trans fatty acids to the precursor essential fatty acid linoleic acid. In contrast, we found significant inverse correlations of trans octadecenoic acid and total trans isomers to the principal n-6 metabolite arachidonic acid as well as to the sum of all n-6 metabolites. Furthermore, there was an inverse correlation of total trans fatty acids to the ratio of arachidonic to linoleic acid, an indirect indicator of linoleic acid conversion. These findings are compatible with inhibition of arachidonic acid biosynthesis by trans fatty acids. Since the availability of long-chain polyunsaturated fatty acids, including arachidonic acid, is of essential importance for tissue growth and development, these findings question the safety of high dietary trans fatty acid intakes in childhood.

Adolescent↗
PubMed1997

Metabolic aspects of trans fatty acids.

The consumption of trans isomers of unsaturated fatty acids has been associated withuntoward metabolic effects. Several clinical investigations demonstrated that trans fatty acids increase plasma LDL-cholesterol and lipoprotein (a) and reduce HDL-cholesterol concentrations. These alterations of plasma lipid profiles indicate an atherogenic effect of trans fatty acids. Both in preterm infants and in healthy children aged 1-15 years, we found blood plasma arachidonic acid (C20:4omega-6) levels and the product/substrate ratios of arachidonic acid synthesis (C20:4omega-6/C18:2omega-6) inversely correlated to the level of the principal trans fatty acid, trans octadecaenoic acid (C18:1omega-9/7, trans), which is compatible with a dose-dependent inhibition of arachidonic acid synthesis by trans fatty acids. Moreover, in premature infants trans fatty acids in blood plasma correlated inversely with birth weight in an observational study, indicating that trans fatty acids may impair early human growth. It appears desirable to limit the dietary intake of trans fatty acids. The major dietary sources of trans fatty acids are partially hydrogenated vegetable and fish oils. Refinement of the industrial technology of partial hydrogenation and appropriate food labelling may lead to a considerably decrease of human exposure to trans fatty acids.

Journal Article↗
PubMed2001

Dietary trans fatty acids in early life: a review.

Trans fatty acids are unsaturated fatty acids with at least a double trans configuration, resulting in a more rigid molecule close to a saturated fatty acid. These appear in dairy fat because of ruminal activity, and in hydrogenated oils; margarines, shortenings and baked goods contain relatively high levels of trans fatty acids. These fatty acids can be incorporated into both fetal and adult tissues, although the transfer rate through the placenta continues to be a contradictory subject. In preterm infants and healthy term babies, trans isomers have been inversely correlated to infantile birth weight. However, in multigenerational studies using animals, there is no correlation between birth weight, growth, and dietary trans fatty acids. Maternal milk reflects precisely the daily dietary intake of trans fatty acids, from 2% to 5% of the total fatty acids in human milk. The level of linoleic acid in human milk is increased by a high trans diet, but long-chain polyunsaturated fatty acids remain mostly unaffected. Likewise, infant tissues incorporate trans fatty acids from maternal milk, raising the level of linoleic acid and relatively decreasing arachidonic and docosahexaenoic acids. This suggests an inhibitory effect of trans fatty acid on liver Delta-6 fatty-acid desaturase activity. As opposed to blood and liver, the brain appears to be protected from the trans fatty-acid accumulation in experimental animals, but no data have yet been reported for human newborns. Further investigations in humans are needed to definitively establish the potential physiological consequences of trans fatty-acid intake during the neonatal period.

Animals↗
PubMed2001

Trans-fatty acids and colon cancer.

Trans-fatty acids have been hypothesized to be carcinogenic, although there are limited data in humans testing this hypothesis. In this study, we examine the association between trans-fatty acids and colon cancer using data from a case (n = 1,993)-control (n = 2,410) study conducted in Utah, Northern California, and Minnesota. Dietary data were collected using a detailed diet history questionnaire, and nutrient values were generated from the Nutrition Coordinating Center nutrient database. After adjustment for other variables, including age at diagnosis, body size, physical activity, aspirin and/or nonsteroidal anti-inflammatory drug (referred to collectively as NSAIDs) use, energy intake, and dietary fiber and calcium, we found a weak association in women [odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.1-2.0] but not in men (OR = 1.2, 95% CI = 0.9-1.7); no increased risk was observed for the cis form of the fatty acids. For men and women, slightly stronger associations were observed in those > or = 67 years of age (OR = 1.4, 95% CI = 0.9-2.1 for men; OR = 1.6, 95% CI = 1.0-2.4 for women). Those who did not use NSAIDs were at a 50% greater risk of developing colon cancer when they consumed high levels of trans-fatty acids. Women who were estrogen negative, i.e., postmenopausal not taking hormone replace therapy, had a twofold increase in risk from high levels of trans-fatty acids in the diet, while women who were estrogen positive did not experience an increased risk of colon cancer, regardless of level of trans-fatty acids consumed. We believe that these data have important public health implications. It seems prudent to avoid consuming partially hydrogenated fats, since no increased risk was observed for the cis form of fatty acids, while suggestions of increased risk from trans-fatty acids exist for subsets of the population.

Aged↗
PubMed1999

An optimized method for fatty acid analysis, including quantification of trans fatty acids, in human adipose tissue by gas-liquid chromatography.

Considering the need for a quick direct method for measurement of the fatty acid composition including trans isomers of human adipose tissue we have developed a procedure using gas-liquid chromatography (GLC) alone, which is thus suitable for validation of fatty acid status in epidemiological studies. Fatty acids ranging in carbon number from 12 to 22 and with 0-6 double bonds were resolved and identified by capillary column GLC with a temperature program starting at 150 degrees C. Following injection, the oven temperature was increased at a rate of 3 degrees C/min to 200 degrees C, then held constant for 25 min, and finally raised at 25 degrees C/min to 225 degrees C. The trans and cis isomers of 18:1 were well separated from each other, as shown by silver-ion thin-layer chromatography. Verification by standards showed that the trans 18:1 isomers with a double bond in position 12 or lower were separated from the cis 18:1 isomers with a double bond in position 6 or higher. As the adipose tissue samples contained only small amounts of the 13t-, 14t- and 15t-18:1 isomers and the 4c- and 5c-18:1 isomers the overlapping was found to be minimal. The GLC method may also be valuable for determining the fatty acid profiles including total trans in other tissues.

Adipose Tissue↗
PubMed1999

Nutritional properties of trans fatty acids.

The role of trans fatty acids (TFA) present in partially hydrogenated fats widely consumed in food and their link with coronary heart disease has been examined in this review. Most of the studies carried out have been on the effects of TFA on blood-lipid profile. The perceived effects of TFA intake depend on the fat or oil with which they are compared and appears to be in between that of dietary saturated fats and monounsaturated fatty acids. When compared to saturated fat, TFA intake shows lower levels of total and LDL-cholesterol in blood. But when both TFA and saturated fatty acids are compared with cis fatty acids or native unhydrogenated oil, increase in total and LDL-cholesterol are noted. The effects of TFA on HDL-cholesterol and Lp(a) are not clearly established. The undesirable effects of TFA can be overcome by inclusion of essential fatty acids at a minimum of 2 energy per cent level in the diet. The link between trans fatty acid intake and coronary heart disease (CHD) are not unequivocally established.

Blood Coagulation Factors↗
PubMed1999

Metabolism of trans fatty acids by hepatocytes.

The present work was undertaken to study the metabolism of fatty acids with trans double bonds by rat hepatocytes. In liver mitochondria, elaidoyl-CoA was a poorer substrate for carnitine palmitoyltransferase I (CPT-I) than oleoyl-CoA. Likewise, incubation of hepatocytes with oleic acid produced a more pronounced stimulation of CPT-I than incubation with trans fatty acids. This was not due to a differential effect of cis and trans fatty acids on acetyl-CoA carboxylase (ACC) activity and malonyl-CoA levels. Elaidic acid was metabolized by hepatocytes at a higher rate than oleic acid. Surprisingly, compared to oleic acid, elaidic acid was a better substrate for mitochondrial and, especially, peroxisomal oxidation, but a poorer substrate for cellular and very low density lipoprotein triacylglycerol synthesis. Results thus show that trans fatty acids are preferentially oxidized by hepatic peroxisomes, and that the ACC/malonyl-CoA/CPT-I system for coordinate control of fatty acid metabolism is not responsible for the distinct hepatic utilization of cis and trans fatty acids.

Acetyl-CoA Carboxylase↗
PubMed2006

[Trans fatty acids: foods and effects on health].

Trans fatty acids can be found in foods derived from ruminant animals and foods that contain partially hydrogenated fat such as fast foods. The consumption of trans fatty acids is larger in the United States, Canada, and some European countries than in Japan and Mediterranean countries. The incidence of coronary heart diseases is higher in countries where the consumption of trans fatty is high. Studies show that trans fatty acids can contribute to increase LDL and lipoprotein [a], and to reduce the levels of HDL. In addition, trans isomeric seems to inhibit the action of desaturase enzymes of essential fatty acids (A5- and A6-desaturase) by holding back the biosynthesis of important fatty acids such as arachidonic acid and docosahexaenoic acid (DHA). With respect to pregnant women's and infant's health, concentrations of trans fatty acids ingested by the mother are associated to concentrations found in the maternal milk. Besides the milk, the trans fatty acids can be transferred to the newly born through the placenta. Studies suggest that trans fatty acids can affect intrauterine growth due to the inhibition of the conversion of essential fatty acids by desaturase enzymes. The inhibition of DHA can also cause early atherosclerosis lesion. However, studies on the effects of trans fatty acids on health are still inconclusive and there are no current recommendations on their consumption. Additionally, in Brazil, studies to determine the composition of trans isomeric in foods are still incipient, which indicates a great need of research in this area.

Cardiovascular Diseases↗