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PubMed1994

Comparison of body weight and adipose tissue in male C57Bl/6J mice fed diets with and without trans fatty acids.

The effect of a diet containing trans-fatty acids (tFA) on the fatty acid composition and fat accumulation in adipose tissue was investigated in mice. Male C57Bl/6J mice were fed Control or Trans Diets that were similar, except that 50% of the 18:1, which was all cis in the Control Diet, was replaced by tFA in the Trans Diet. At selected ages, body weight, epididymal fat pad weight, perirenal fat yield, adipose tissue cellularity and fatty acid composition were examined. Over the time period studied (2-24 mon), the proportion of 18:0 and 16:0 tended to decrease while cis-18:1 levels increased. Compared to the Control Diet, the Trans Diet resulted in adipose tissue lipids with higher percentages of 14:0 and 18:2n-6 and lower percentages of cis-18:1 and 20:4n-6. In polar lipids, tFA replaced saturated fatty acids, whereas tFA replaced cis-18:1 in the nonpolar lipids. Body weights at 16 and 24 mon of age and epididymal fat pad weights at 8-24 mon of age were lower in mice fed the Trans Diet as compared to those fed the Control Diet. At the ages studied, the Trans Diet also resulted in lower values for perirenal fat weights, triacylglycerol to polar lipid ratios, and adipose cell size. The data suggest that chronic consumption of tFA affects lipid metabolism and results in decreased fat accumulation in murine adipose tissue.

Adipose Tissue↗
PubMed1985

Effect of dietary trans fatty acids on microsomal enzymes and membranes.

Three groups of rats were maintained on diets containing different proportions of trans fatty acids (0, 18.3 or 36.6% of the total fatty acids) for eight weeks. No differences in body weight were observed among the three groups, but the fat cell size, determined in epididymal fat, differed significantly between the controls and the rats fed diets containing trans fatty acids. The supernatant obtained by centrifuging homogenates of liver from the rats at 9000 X g (S-9 fraction) was used as an activator in a bacterial test for mutagenicity of 2-aminofluorene and aflatoxin B1 using Salmonella typhimurium strains TA 98 and TA 100, respectively. The mutagenicities of 2-aminofluorene in strain TA 98 and of aflatoxin B1 in strain TA 100 were significantly lower with the liver S-9 fraction from rats fed a diet containing 36.6% trans fatty acids than with the liver S-9 fraction from rats fed a control diet with no trans fatty acids.

Adipose Tissue↗
PubMed1994

[Content of trans-fatty acids in food].

The fatty acid composition of the fat in 197 food samples has been analyzed by gas liquid chromatography. The use of a 30 m capillary column coated with CPSil88 permitted the separation of the cis and trans isomers. The trans fatty acid content of milk and milk products ranged from 1.9 to 7.9%. Meat samples from ruminants contained 2.0-10.6% trans fatty acids. In pork fat the amounts were less than 0.5%. Sausages and other meat products contained high levels of pork fat. Therefore these samples contained less than 1% trans fatty acids, with the exception of some pure beef products. The amounts of trans fatty acids in foods which may contain hydrogenated oils ranged from 0 to 34.9%. In food samples with high levels of trans fatty acids lower contents of saturated fatty acids were analyzed.

Animals↗
PubMed1998

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

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.

Animals↗
PubMed2000

Milk composition and apparent digestibilities of dietary fatty acids in lactating dairy cows abomasally infused with Cis or Trans fatty acids.

Fat supplementation of diets for dairy cows produces changes in nutrient supply and milk composition. The effect of abomasal infusion of either cis-C18:1 or trans-C18:1 fatty acid isomers on the digestibility of fatty acids and milk composition was determined in lactating dairy cows. Six multiparous midlactation Holstein cows were used and fed a control diet containing 50% forage and 50% concentrate. Treatments were (per day): no infusion, infusion of a 630-g fat mixture high in cis-C18:1 isomers, and infusion of a 623-g fat mixture high in trans-C18:1 isomers using two 3 x 3 Latin squares with 4-wk experimental periods. Fat infusion did not affect total dry matter intake and increased apparent digestibilities of total fatty acids. Apparent digestibilities of C18 fatty acids were directly related to the number of double bonds within isomers, and cis-C18:1 isomers were slightly more digestible than trans-C18:1 isomers. The lower yield of C12:0, C14:0, and C16:0 fatty acids in milk fat and higher milk citrate observed when cows were infused with trans-C18:1 suggests a depressed de novo milk fatty acid synthesis. Effects of trans infusion on milk fat were independent of ruminal fermentation, fatty acid apparent absorption, and fatty acid plasma concentrations. Lower milk protein yield in cows infused with fat may have been caused by a decrease in milk protein synthesis.

Abomasum↗
PubMed1994

Dietary saturated and trans fatty acids and lipoprotein metabolism.

Earlier studies have shown that not all saturated fatty acids are equally hypercholesterolaemic: stearic acid (C18:0) and saturated fatty acids with less than 12 carbon atoms are thought not to raise serum cholesterol levels. This suggests that the cholesterol-raising effects of saturated fatty acids can be attributed to lauric acid (C12:0), myristic acid (C14:0) and palmitic acid (C16:0). These three saturated fatty acids also have different effects on serum total cholesterol levels. Results from recent controlled dietary experiments suggest that lauric acid raises serum total and low-density lipoprotein (LDL) cholesterol levels slightly less, and myristic acid more, as compared with palmitic acid. Myristic acid, however, also causes higher levels of high-density lipoprotein (HDL) cholesterol. Stearic acid has only a slight effect on serum LDL and HDL cholesterol levels as compared with oleic acid. Trans monounsaturated fatty acids, however, increase LDL and decrease HDL cholesterol levels. Precise effects on lipoproteins of short and medium chain triglycerides (C4:0-C10:0) have never been examined.

Cholesterol, HDL↗
PubMed2003

Trans fatty acids, HDL-cholesterol, and cardiovascular disease. Effects of dietary changes on vascular reactivity.

A high consumption of trans fatty acids increases the risk of cardiovascular disease (CVD). We investigated whether this increase in risk was due to the decrease in serum HDL-cholesterol by trans fatty acids, because low concentrations of serum HDL-cholesterol also increase risk of CVD. Flow-mediated vasodilation (FMD) was used as an endpoint in dietary interventions that were designed to change the concentration of serum HDL-cholesterol within 4 weeks in healthy volunteers. Replacement of 10% of energy from saturated by trans fatty acids decreased serum HDL-cholesterol by 21 % and impaired FMD. However, a replacement of monounsaturated fats by carbohydrates did not impair FMD, although it decreased serum HDL-cholesterol by 13%. Acute postprandial impairments of FMD by either trans fats or saturated fats were not found, suggesting that long-term effects are responsible for the detrimental effect of trans fats on health. However, the role of serum HDL-cholesterol appears to be less than we expected.

Adult↗
PubMed1980

Effect of trans fatty acids on serum lecithin: cholesterol acyltransferase in rats.

An investigation was undertaken to study the effect of trans isomers of octadecenoic (18:1) and octadecadienoic (18:2) acids on serum lecithin:cholesterol acyltransferase (LCAT). Male rats of the Wistar strain were fed diets containing 15% fat for 9 months. The fat diets were either hydrogenated fat mixtures containing trans fatty acids, corn oil or lard. At the end of 9 months, rats were killed and serum cholesterol levels and LCAT activity were measured. It was found that free and total serum cholesterol levels were decreased when animals were fed trans fatty acids when compared with animals fed corn oil or lard. Although in vitro studies indicated that the percentage of cholesterol esterified in serum was not affected by the presence of dietary trans fatty acids, LCAT activity generally decreased when trans fatty acids were fed to rats for 9 months. In this study a negative correlation was found between serum free cholesterol and LCAT activity. Depressed total LCAT activity (mumoles of cholesterol esterified per hour per liter of serum) may have been related to a reduced amount of substrate (free cholesterol).

Animals↗
PubMed1994

Trans fatty acids: are the effects only marginal?

In the process of converting vegetable oils into solid fats, a process known as partial hydrogenation, some unsaturated bonds are converted to an unnatural trans position. In humans, trans fatty acids increase low-density lipoprotein cholesterol and decrease high-density lipoprotein cholesterol. In addition, positive associations between intake of trans fatty acids and coronary heart disease have been observed in epidemiological studies. The combined results of metabolic and epidemiological studies provide strong evidence that trans fatty acid intake is causally related to risk of coronary disease. Because the consumption of partially hydrogenated fats is almost universal in the United States, the number of deaths attributable to such fats is likely to be substantial. Federal regulations should require manufacturers to include trans fatty acid content in food labels and should aim to greatly reduce or eliminate the use of partially hydrogenated vegetable fats.

Coronary Disease↗
PubMed1990

Conjugated diene and trans fatty acids in a choline-devoid diet hepatocarcinogenic in the rat.

It has been postulated that the hepatocarcinogenicity of a choline-devoid diet in rats stems from peroxidation of liver lipids. We have investigated whether the diet contains conjugated dienes that could account directly for those detected in liver lipids of rats fed a choline-devoid diet. Analyses were performed on samples of corn oil and of a partially hydrogenated fat used to prepare semipurified choline-devoid and choline-supplemented diets, and on fat extracted from two pairs of diets, one set containing 5% corn oil and 10% partially hydrogenated fat, and the other only corn oil (15%). The analyses consisted of quantitation of conjugated dienes by UV spectrophotometry, separation of fatty acids with conjugated dienes by HPLC, and quantitation of trans fatty acids by IR spectrophotometry. Small levels of conjugated diene and trans fatty acids were present in the corn oil, but much higher amounts were found in the partially hydrogenated fat. HPLC analysis yielded distinct elution profiles for the fatty acids with conjugated dienes present in the two fats, and similar results were obtained with fat extracted from the diets. However, no differences were observed between choline-devoid and control choline-supplemented diets. The results indicate that caution must be exercised in interpreting data from UV analysis of tissue lipids of rats fed diets containing a partially hydrogenated fat.

Animals↗
PubMed1995

Dietary saturated and trans fatty acids and cholesterol and 25-year mortality from coronary heart disease: the Seven Countries Study.

BACKGROUND: In the Seven Countries Study associations between intake of individual fatty acids and dietary cholesterol were studied in relation to serum cholesterol and 25-year mortality from coronary heart disease. All analyses concern only intercohort comparisons. METHODS: In the baseline surveys carried out between 1958 and 1964, risk factors for coronary heart disease were measured among 12,763 middle-aged men constituting 16 cohorts in seven countries. In 1987 and 1988 equivalent food composites representing the average food intake of each cohort at baseline were collected locally and analyzed in a central laboratory. The vital status of all participants was verified at regular intervals during 25 years of follow-up. RESULTS: Of the individual saturated fatty acids, the average population intake of lauric and myristic acid was most strongly related to the average serum cholesterol level (r > 0.8, P < 0.001). Strong positive associations were observed between 25-year death rates from coronary heart disease and average intake of the four major saturated fatty acids, lauric, myristic, palmitic, and stearic acid (r > 0.8, P < 0.001); the trans fatty acid elaidic acid (r = 0.78, P < 0.001); and dietary cholesterol (r = 0.55, P < 0.05). CONCLUSIONS: Interpreted in the light of experimental and clinical studies, the results of these cross-cultural analyses suggest that dietary saturated and trans fatty acids and dietary cholesterol are important determinants of differences in population rates of coronary heart disease death.

Adult↗
PubMed2006

Trans fatty acids and coronary heart disease.

Epidemiologic evidence has linked trans fatty acids (TFAs) in the diet to coronary heart disease in human populations. It has been estimated that dietary TFAs from partially hydrogenated oils may be responsible for between 30,000 and 100,000 premature coronary deaths per year in the United States. Although it is known that TFAs increase low-density lipoprotein (LDL) cholesterol levels and decrease high-density lipoprotein (HDL) cholesterol levels (markers of coronary heart disease), there is little known about the mechanisms by which TFAs actually function at the cellular level. It is unknown what levels of TFAs are clinically significant and it is unclear how TFAs are associated with cardiac arrhythmias or sudden cardiac death. We hypothesize that TFAs affect membrane structure, thus altering enzymatic pathways that may subsequently induce cardiac arrhythmias and sudden death.

Cholesterol, LDL↗
PubMed2006

[High levels of industrially produced trans fatty acids in popular fast food - but not in Denmark--secondary publication].

An intake of trans-fatty acids of 5 grams per day is associated with an increase of 25% in the risk of ischemic heart disease. In 2004 Denmark, as the first country in the world, introduced a limitation on the content of industrially produced trans-fatty acids in foods. The amount in a "high-trans menu" consisting of popular foods was, from 2001 to 2005, reduced in Denmark from 30 g to <1 g. The amount in the same menu bought in countries within and outside the European Union is 20-40 g. During a period of just a few years, Denmark has thus eliminated a risk factor for ischemic heart disease without noticeable side effects for consumers. This risk factor is, however, still present in many other countries.

Animals↗
PubMed1982

Interrelationship between dietary trans Fatty acids and the 6- and 9-desaturases in the rat.

Studies are reported on the effects of dietary trans fatty acids on the 6- and 9-acyl desaturase activities in the liver microsomes of rats fed essential fatty acid (EFA)-deficient and non-EFA-deficient diets. In experiment I, weanling male rats were fed a semisynthetic diet with either 10% safflower oil (SAF) or 10% hydrogenated coconut oil (HCO). At the age of one year, half of the dietary fat was replaced by a supplement containing elaidate, linolelaidate and cis, trans-trans,cis-18:2 (TRANS) for 12 weeks. In experiment II, male rats which were kept from weaning on a 10% (SAF + TRANS, or 5% HCO + 5% TRANS. Feeding TRANS depressed the 6-desaturase activity in the liver microsomes, especially in the EFA-deficient rats (HCO + TRANS group of experiment I). Unlike the 6-deaturase activity, the 9-desaturase activity was not inhibited by the dietary trans fatty acids and was significantly stimulated in the non-EFA-deficient rats (SAF + TRANS group of experiment I and HCO + TRANS groups of experiment II). This was evidence by incubation reaction and by comparisons of fatty acid consumptions and microsomal fatty acid levels, showing extra biosynthesis of 16:1 and 18:1 when TRANS was fed. The biosynthesis of essential (n-6) fatty acids was depressed by the TRANS supplement in EFA-deficient as well as in non-EFA-deficient animals.

Animals↗
PubMed2003

Monensin by fat interactions on trans fatty acids in cultures of mixed ruminal microorganisms grown in continuous fermentors fed corn or barley.

In previous studies, monensin (M) and unsaturated plant oils independently increased trans fatty acid concentrations in cultures of mixed ruminal microorganisms. This study was conducted to determine if combining M with plant oil yielded interactions on trans fatty acid concentrations in cultures of mixed ruminal microorganisms or their effects were additive. Four continuous fermentors were fed 14 g of dry feed per day (divided equally between two feedings), consisting of alfalfa hay pellets (30% of DM) and either a high corn (HC) or a high barley (BB) concentrate (70% of DM) in each of two fermentors. Within each grain type, one fermentor was supplemented with M (25 ppm), and the other fermentor was supplemented with 5% soybean oil (SBO) during d 5 to 8. Monensin and SBO were added together in all fermentors during d 9 to 12. Samples were taken at 2 h after the morning feeding on the last day of each period and analyzed for fatty acids by gas-liquid chromatography. A second run of the fermentors followed the same treatment sequence to give additional replication. Average pH across all treatments was 6.15, which was reduced by M but not affected by SBO. Monensin reduced the ratio of acetate to propionate (A:P), which averaged 2.03 across all treatments; fat decreased A:P in cultures not receiving M but increased it in the presence of M. Monensin and SBO altered the concentration of several trans fatty acids, but the only interaction was a grain x M x SBO interaction for trans-10 C18:1. The increase in trans-10 C18:1 by the M and SBO combination exceeded the sum of increases in trans-10 C18:1 for each individual feed additive, but only for KB. For the HC diet, M increased trans-10 C18:1 more than fat alone and more than the M and SBO combination. The results of this study show that M and SBO effects are additive for all trans FA except for trans-10 C18:1. In the case of trans-10 C18:1, M and SBO interacted to give higher trans-10 C18:1 concentrations in ruminal contents than would be expected simply by adding their individual effects, but only for HB. Because some trans fatty acid isomers have been associated with milk fat depression in dairy cows, these results suggest more severe depressions in milk fat content when cows are fed M along with unsaturated plant oils.

Animal Feed↗
PubMed1984

Dietary trans-fatty acid effects on mitochondrial functionality and phospholipid composition in rat perfused hearts in oxygenation and anoxia.

Dietary fatty acid fraction influence on heart composition is known and we have previously demonstrated a trans-fatty acid accumulation in heart. In this work we will verify trans-fatty acid effect on heart phospholipid fatty acid composition and miocardic mitochondrial respiratory activity under the influence of perfusion techniques in oxygenation and anoxic conditions. Results have pointed out, in group fed with 28% trans-fatty acid hydrogenated fat, a decreased mitochondrial functionality during perfusion in different oxygenation condition, probably correlated to different fatty acid composition of heart phospholipids.

Animals↗
PubMed1981

Trans fatty acids in tumor development and the host survival.

Because trans fatty acids exist in the American diet and their relationship to cancer incidence has been proposed, studies were designed to investigate their possible role in the development of Ehrlich tumor cells in inbred CBA mice. Feeding elaidic acid (18:1 delta 9, trans) to Ehrlich ascites tumor-bearing animals resulted in tumors that incorporated more thymidine into their cells and into their acid-insoluble fraction as compared with those grown in animals fed the natural oleic acid (18:1 delta 3, cis)-rich diet. Elaidic acid diet feeding at 5% in the diet also resulted in a reduction in the host survival rate. This reduction ranged from 23 to 45%.

Animals↗