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PubMed1996

Position paper on trans fatty acids. ASCN/AIN Task Force on Trans Fatty Acids. American Society for Clinical Nutrition and American Institute of Nutrition.

This report addresses the current controversy about possible health hazards of dietary trans fatty acid isomers, which are created during hydrogenation of unsaturated fats to change their textural properties and melting points. Estimates of intakes are approximations based on limited data and problematic analytic techniques. Major contributors in the diet are fried and baked foods and margarine, in which partially hydrogenated vegetable oils may replace fat sources richer in saturated fatty acids and cholesterol. Consumption of trans fatty acids in the United States has been relatively constant, and new food technologies are yielding decreases in the trans fatty acid content of commercially prepared foods. When intake of trans fatty acids (as hydrogenated fat) is compared with that of saturated fat, total and low-density-lipoprotein (LDL)-cholesterol concentrations in blood are lower, but both trans fats and saturated fats increase total and LDL concentrations when compared with cis fatty acids or native unhydrogenated fat. Epidemiologic data are conflicting with respect to cardiovascular disease outcomes. We cannot conclude that the intake of trans fatty acids is a risk factor for coronary heart disease nor can we expect that substituting trans- for cis-containing fats will reduce the risk of coronary heart disease. Few rigorous studies have dealt with biomedical effects of trans fatty acids and possible mechanisms relevant to human health and diseases. The nutrition labeling issue is unresolved. The options, recommendations, and research suggestions in this report should outline for nutrition scientists the database needed before any new dietary recommendations or changes in nutrition policy concerning trans fatty acids can be made. The debate about trans fatty acids should not detract from dietary recommendations to limit the intake of saturated fat and total fat.

Cardiovascular Diseases↗
PubMed1978

[Behavior of blood amino acids and fatty acids during complete parenteral hyperalimentation with carbohydrates, amino acids and fats].

Over a period of 12 hours a total amount of 190 g fructose, 190 g glucose, 145 g xylitol, 96 g fat and 99 g amino acids were infused. The utilization of carbohydrate was not diminished despite the high fat load. In addition, the antiketogenic action of carbohydrate was still provable. The nitrogen balance was positive as an indicator of good utilization of amino acids. Therefore, simultaneous administration of a carbohydrate mixture and a fat emulsion as energy sources during application of amino acids is recommended.

Acid-Base Equilibrium↗
PubMed1991

Effects of altering umbilical flow and umbilical free fatty acid concentration on transfer of free fatty acids across the rabbit placenta.

The transfer of free fatty acids across the placenta perfused in situ was studied in anaesthetized rabbits in late gestation. In the first series of experiments, umbilical flow rate was varied between 0.6 and 4.0 ml/min in nine rabbits. Although increasing umbilical flow rate significantly decreased the free fatty acid concentration in the umbilical venous effluent (P = 0.0001), placental clearance of free fatty acids from the maternal circulation was not significantly changed by alterations in umbilical flow rate. In the second series of experiments, the materno-fetal free fatty acid concentration gradient was varied between + 1.58 mmol/l and -2.81 mmol/l in eight rabbits. There was a significant relationship between increasing materno-fetal gradient and increasing transfer of free fatty acids across the placenta (P less than 0.001). Moreover, net transfer of free fatty acids into the umbilical circulation was observed even with zero concentration gradient. Net transfer of free fatty acids from fetus to mother occurred when umbilical arterial free fatty acid concentration exceeded maternal arterial concentration by 1.3 mmol/l.

Analysis of Variance↗
PubMed1989

Effect of essential fatty acid depletion on tissue phospholipid fatty acids in spontaneously hypertensive and normotensive rats.

Weanling male spontaneously hypertensive (SHR) and normotensive (WKY) rats were maintained on a fat-free semisynthetic diet and killed at various intervals. The effects of fat-depletion on the appearance of essential fatty acid (EFA) deficiency symptoms, the progressive changes of major fatty acids in plasma, liver, heart, and kidney phospholipids (PL), and in skin total lipids were compared between these two strains. After five weeks on the diet, the slower growth and the appearance of EFA deficiency symptoms became evident in SHR. In general, fat-depletion reduced the levels of n-6 fatty acids, whereas it increased those of 20:3n-9. However, the fat-depletion induced reduction of 18:2n-6 in heart PL and 20:4n-6 in kidney, while the elevation of 20:3n-9 in plasma, heart, and kidney PL were greater in WKY than in SHR. As a result, the elevation of biochemical EFA deficiency index--20:3n-9/20:4n-6 ratio--was greater in WKY than in SHR. In comparison with WKY, the concentrations of liver triacylglycerols and the weights of adipose tissues in SHR were reduced to a greater extent, indicating an active catabolism of triacylglycerols in SHR. This study suggests that the earlier appearance of morphological symptoms of EFA deficiency in SHR was not associated with the reducing n-6 EFA levels or with an elevation of triene/tetraene ratio, but possibly to a reduced supply of n-6 EFA for skin prostaglandin synthesis.

Animals↗
PubMed1998

Transcriptional co-regulation of Saccharomyces cerevisiae alcohol acetyltransferase gene, ATF1 and delta-9 fatty acid desaturase gene, OLE1 by unsaturated fatty acids.

The ATF1 gene encodes an alcohol acetyl transferase which catalyzes the synthesis of acetate esters from acetyl CoA and several kinds of alcohols. ATF1 expression is repressed by unsaturated fatty acids or oxygen. Analysis using ATF1-lacZ fusion plasmid revealed that ATF1 gene expression is widely repressed by a variety of unsaturated fatty acids, and the degree of ATF1 transcriptional repression varies according to the structure of the unsaturated fatty acids. Interestingly, it was noted that the degree of ATF1 transcriptional repression was related to the melting point of unsaturated fatty acids added to the medium. The OLE1 gene, which encodes delta-9 fatty acid desaturase, has been reported to be repressed by unsaturated fatty acids. Transcription of OLE1 was also repressed by a wide variety of unsaturated fatty acids under anaerobic conditions. The degree of transcriptional repression of OLE1 was also related to the melting point of the added unsaturated fatty acids. Therefore, it is considered that ATF1 and OLE1 transcription are regulated in response to cell membrane fluidity. As has been reported for OLE1, the repression of ATF1 by unsaturated fatty acids was relieved in a disruptant carrying a faa1 and faa4 double mutation, two fatty acid activation genes. However, the ATF1 transcript in this double gene disruptant was repressed by oxygen. These results suggested that ATF1 transcription was co-regulated by the same mechanism as the OLE1 gene and that unsaturated fatty acids and oxygen repressed the ATF1 transcript by a different regulation pathway.

Acetyltransferases↗
PubMed2006

Effects of various fat sources, alpha-tocopheryl acetate, and ascorbic acid supplements on fatty acid composition and alpha-tocopherol content in raw and vacuum-packed, cooked dark chicken meat.

A factorial design was used to study the effects of dietary fat sources (beef tallow, fresh and oxidized sunflower oils, and linseed oil), alpha-tocopheryl acetate (0 and 225 mg/kg), and ascorbic acid (0 and 110 mg/ kg) supplementation on fatty acid composition, as well as on fat and alpha-tocopherol content in vacuum-packed raw and cooked meat stored at -20 degrees C. Raw meat fatty acid composition was affected by dietary fat sources and tocopheryl acetate supplementation. After cooking, meat composition was only affected by dietary fat sources. Birds fed linseed oil yielded meat rich in n-3 fatty acids, especially linolenic acid, which provides about 20% of the adequate intake for this fatty acid. Birds fed sunflower or oxidized sunflower oil produced meat rich in n-6 fatty acids, whereas those fed beef tallow resulted in meat rich in saturated and monounsaturated fatty acids. Raw and cooked dark chicken meat alpha-tocopherol content was only affected by tocopherol supplementation. Supplementation with alpha-tocopheryl acetate led to alpha-tocopherol-enriched meat, which provides about 25% of the recommended dietary allowance. Moreover, this content in vacuum-packed samples was not modified even after 7 mo of storage at -20 degrees C.

Animal Feed↗
PubMed1992

Comparative effects of oxygen and sulfur-substituted fatty acids on serum lipids and mitochondrial and peroxisomal fatty acid oxidation in rat.

Feeding tetradecyloxyacetic acid (a 3-oxa fatty acid) to rats led to decreased serum cholesterol and decreased serum triacylglycerol, resembling the effects of the corresponding 3-thia fatty acid (tetradecylthioacetic acid). The 3-oxa fatty acid inhibited strongly the mitochondrial fatty acid oxidation and led to the development of fatty liver, while the 3-thia fatty acid stimulated the mitochondrial fatty acid oxidation. Feeding tetradecyloxypropionic acid (a 4-oxa fatty acid) had less effect on the serum lipids. It stimulated fatty acid oxidation in the mitochondria and lowered the hepatic level of triacylglycerol. The corresponding 4-thia fatty acid (tetradecylthiopropionic acid) inhibited mitochondrial fatty acid oxidation and induced development of fatty liver. All these compounds, both the oxa and the thia fatty acids, induced some increase in the activity of the peroxisomal acyl-CoA oxidase. Repeated administration of 3-oxadicarboxylic acid to rats resulted in no lipid lowering effects, and marginal changes of fatty acyl-CoA oxidase activity. Oxidation of the S-atom of the 3-thia fatty acid to the corresponding sulfoxide or sulfone eliminated the metabolic effects of the thia fatty acid. The study has shown that the effects of 3- and 4-oxa fatty acids are in some ways opposite to those of the 3- and 4-thia fatty acids. The possibility that the lipophilicity of the fatty acid analogues may be an important factor behind the differences observed are discussed. It is suggested that these oxa- and thia-analogues of fatty acids may be useful in studies on the regulation of fatty acid metabolism.

Animals↗
PubMed1997

Linoleic and alpha-linolenic acids differently modify the effects of elaidic acid on polyunsaturated fatty acid metabolism and some immune indices in rats.

To explore whether the metabolic responses to trans, compared with cis, fatty acids depend on the source of dietary polyunsaturated fatty acids (PUFA), male Sprague-Dawley rats, 5 weeks old, were fed on diets containing 30 g oleic (cis) or elaidic (trans) acids/kg in combination with either 70 g perilla oil (alpha-linolenic acid) or safflowerseed oil (linoleic acid)/kg for 3 weeks in separate experiments. The dietary fats were adjusted to have the same level of total PUFA. The dietary manipulation did not influence the growth indices, but spleen weight was greater when the dietary PUFA source was perilla oil. The incorporation of trans fatty acid into liver phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine and adipose tissue lipids, particularly phospholipids, was significantly higher when rats were fed on safflowerseed oil compared with perilla oil. However, only limited differences were observed in the effects of cis and trans fatty acids on the proportions of PUFA in liver phospholipids. Splenic production of prostaglandin E2 was reduced by trans fatty acid when safflowerseed oil was the PUFA source, but no trans effect was observed on leukotriene C4 production. Dietary PUFA significantly influenced the concentration of plasma immunoglobulins (Ig) but the effect of geometry was only seen in IgG which was increased by trans acid. Dietary trans fatty acid increased the CD4+:CD8+ T-lymphocyte ratio in the spleen, reflecting a decreasing trend of the proportion of CD8+, when combined with perilla oil. These observations indicate that the type of PUFA simultaneously ingested specifically influences the effect that trans acid exerts on PUFA metabolism, eicosanoid production and some immune indices.

Animals↗
PubMed1995

Effect of n-3 fatty acid ethyl ester supplementation on fatty acid composition of the single platelet phospholipids and on platelet functions.

Twenty healthy male volunteers were randomly assigned to receive either four 1-g capsules of n-3 polyunsaturated fatty acids (PUFA) ethyl esters or four 1-g capsules of olive oil (as placebo) for a period of 4 months, followed by a 3-month wash-out period. Fatty acids of platelet phospholipid fractions, platelet aggregation, and thromboxane B2 (TXB2) formation were analyzed at 0, 2, and 4 months of treatment and at 1, 2, and 3 months of wash-out. During n-3 PUFA supplementation, accumulations of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids were markedly increased after 2 months, with slight differences in further accumulation up to 4 months among the various phospholipid fractions. Significant decreases in platelet sensitivity to collagen, serum TXB2 levels, and urinary TXB2 metabolites were also observed following n-3 PUFA treatment. During the first and second month of wash-out, slight differences were observed in changes of various fatty acids among different phospholipid fractions, but after 3 months of wash-out, alterations were no longer detectable with respect to pretreatment values. After 3 months of wash-out, platelet function parameters also were returned to baseline. Thus, both platelet lipids and function are influenced by n-3 PUFA ethyl ester supplementation, and significant alterations are still detectable after 2 months of wash-out.

Adult↗
PubMed2003

Effects of highly purified eicosapentaenoic acid on erythrocyte fatty acid composition and leukocyte and colonic mucosa leukotriene B4 production in children with ulcerative colitis.

BACKGROUND: n-3 Polyunsaturated fatty acids (PUFAs) have been suggested as a treatment for ulcerative colitis (UC). However, the efficacy of n-3 PUFAs against UC has not been examined in children. Therefore, the authors investigated the effects of eicosapentaenoic acid (EPA) on fatty acid composition and leukotriene (LT) production in children with UC. METHODS: For 2 months the authors administered highly purified EPA ethyl ester (EPA-E) (1.8 g/d) to children with UC in remission. Colonic mucosal histology, fatty acid composition of erythrocyte membrane phospholipids, and LTB4 production by leukocytes and colonic mucosa were measured before and 2 months after the initiation of EPA-E treatment. RESULTS: No patients relapsed during the study period, and no significant differences were detected in laboratory findings obtained before and 2 months after the initiation of EPA-E ingestion. There were no significant differences in mucosal histologic scores before and 2 months after EPA-E treatment. The EPA levels in erythrocyte membranes 2 months after the initiation of EPA-E treatment were significantly higher than before treatment, but the other fatty acids showed no significant changes. LTB4 production by leukocytes and rectal mucosa after 2 months of EPA-E treatment was significantly lower than before treatment. CONCLUSION: EPA-E treatment increased the levels of EPA in erythrocytes and decreased LTB4 levels produced by leukocytes and colonic mucosa. To assess the concomitant clinical changes, we should examine the long-term effects of EPA-E ingestion on the maintenance of remission in children with UC.

Adolescent↗