Effects of dietary trans fatty acids on blood pressure in normotensive subjects.

Consumption of essential fatty acids of the (n-6) series may affect blood pressure in man. Trans fatty acids in the diet interfere with the metabolism of essential fatty acids in rats. We therefore measured the effect of dietary trans fatty acids on blood pressure in 25 men and 34 women. Each subject consumed, in random order, three mixed natural diets, each for three weeks. The composition of the three diets was similar, except for 10.4 per cent of energy, which was provided by either oleic acid, trans fatty acids, or saturated fatty acids. The intake from polyunsaturated fatty acids was 3.4 per cent on the saturated-fat diet and 4.6 per cent on the other two diets. On the oleic-acid diet systolic blood pressure was 113 +/- 12.8 mmHg and diastolic blood pressure 66 +/- 8.3 mmHg, on the trans-fatty-acid diet 112 +/- 12.2 mmHg and 67 +/- 8.1 mmHg, and on the saturated-fat diet 112 +/- 12.6 mmHg and 67 +/- 8.1 mmHg. No significant differences were observed in blood pressure levels between the three diets. We conclude that neither trans nor saturated fatty acids influence blood pressure levels in normotensive subjects relative to oleic acid.     

Exchanging partially hydrogenated fat for palmitic acid in the diet increases LDL-cholesterol and endogenous cholesterol synthesis in normocholesterolemic women

Partial hydrogenation of oil results in fats containing unusual isomeric fatty acids characterized by cis and trans configurations. Hydrogenated fats containing trans fatty acids increase plasma total cholesterol (TC) and LDL-cholesterol while depressing HDL-cholesterol levels. Identifying the content of trans fatty acids by food labeling is overshadowed by a reluctance of health authorities to label saturates and trans fatty acids separately. Thus, it is pertinent to compare the effects of trans to saturated fatty acids using stable isotope methodology to establish if the mechanism of increase in TC and LDL-cholesterol is due to the increase in the rate of endogenous synthesis of cholesterol. Ten healthy normocholesterolemic female subjects consumed each of two diets containing approximately 30% of energy as fat for a fourweek period. One diet was high in palmitic acid (10.6% of energy) from palm olein and the other diet exchanged 5.6% of energy as partially hydrogenated fat for palmitic acid. This fat blend resulted in monounsaturated fatty acids decreasing by 4.9 % and polyunsaturated fats increasing by 2.7%. The hydrogenated fat diet treatment provided 3.1% of energy as elaidic acid. For each dietary treatment, the fractional synthesis rates for cholesterol were measured using deuterium-labeling procedures and blood samples were obtained for blood lipid and lipoprotein measurements. Subjects exhibited a higher total cholesterol and LDL-cholesterol level when consuming the diet containing trans fatty acids while also depressing the HDL-cholesterol level. Consuming the partially hydrogenated fat diet treatment increased the fractional synthesis rate of free cholesterol. Consumption of hydrogenated fats containing trans fatty acids in comparison to a mixtur e of palmitic and oleic acids increase plasma cholesterol levels apparently by increasing endogenous synthesis of cholesterol.     

Intake of trans fatty acid-rich hydrogenated fat during pregnancy and lactation inhibits the hypophagic effect of central insulin in the adult offspring

OBJECTIVE: Using rats we examined whether maternal intake of hydrogenated fat rich in trans fatty acids affects brain fatty acid profile, hypothalamic content of insulin receptor and insulin receptor substrate-1 proteins, and the hypophagic effect of centrally administered insulin in 3-mo-old male progeny. METHODS: Throughout pregnancy and lactation, Wistar rats ate isocaloric/normolipidic diets with soybean oil (control) or soybean oil-derived hydrogenated fat (trans diet) as a fat source. Upon weaning, the trans offspring continued on the trans diet (trans group) or were switched to a control diet (trans-control group). RESULTS: Compared with control rats, trans rats had lower brain levels of eicosapentaenoic acid. Compared with trans rats, trans-control rats had increased levels of total polyunsaturated fatty acids and arachidonic acid and decreased levels of trans fatty acids, saturated fatty acids, and monounsaturated fatty acids. Insulin receptor and insulin receptor substrate-1 levels were significantly lower (44% and 38%, respectively) in trans than in control rats. In trans-control rats, insulin receptor was 26% lower (P < 0.05), whereas insulin receptor substrate-1 was 50% lower, than in control rats. Insulin decreased 24-h feeding in control (27%) and trans (38%) rats but failed to do so in trans-control rats. The latter group had increased serum glucose levels. CONCLUSIONS: The data suggest that the early (intrauterine/perinatal) exposure to hydrogenated fat rich in trans fatty acids programmed the hypothalamic feeding control mechanisms. As young adults, only trans-control animals showed loss of insulin-induced hypophagia, indicating that the mismatch between early and later nutritional environments was relevant. However, the trans group also showed signs of altered appetite signaling mechanisms, suggesting that the early adaptations may have deleterious consequences later in life.     

Fatty acids and retinyl esters of rat milk: effects of diet and duration of lactation

This study was initiated to explore the quantitative and qualitative differences in milk total fatty acids and milk retinyl esters when either hydrogenated or nonhydrogenated fat is fed during pregnancy and lactation. Rats were fed diets containing 10% by weight of corn oil or partially hydrogenated corn oil. Milk was collected on d 1, 8 and 14 of lactation and analyzed for protein, total fatty acids, fatty acid pattern, and retinyl ester pattern. Whereas diet produced no quantitative differences in milk protein or total fatty acids, the pattern of milk fatty acids varied significantly. Rats fed corn oil produced milk having more medium-chain saturated fatty acids, less long-chain monoenoic fatty acids, and more polyunsaturated fatty acids compared to those fed hydrogenated corn oil. Rats fed hydrogenated corn oil produced milk fat having 21-26% of the trans fatty acid, elaidic acid. Significant differences were also observed with duration of lactation: medium-chain fatty acids increased three to fourfold between d 1 and 8, where cis-monoenes and polyunsaturated fatty acids declined. The pattern of milk retinyl esters strongly reflected, but was not identical to, that of total milk fat. Comparing d 14 milk from rats fed corn oil with that from rats fed hydrogenated corn oil, medium-chain esters of retinol constituted 24 and 11% of total retinyl esters, whereas saturated long-chain fatty acid esters constituted 52 and 44%, respectively. trans Fatty acid esters of retinol comprised 24% of vitamin A esters in milk of rats fed hydrogenated fat. These data provide evidence that the composition of milk retinyl esters, as well as that of total milk fat, is determined both by the type of fatty acids from diet and from diet-related differences in de novo synthesis of fatty acids within the mammary gland and other tissues.     

Variability in the trans fatty acid content of foods within a food category: implications for estimation of dietary trans fatty acid intakes.

OBJECTIVE: Currently, the published information on trans fatty acid composition of foods is incomplete and of questionable accuracy. Detailed fatty acid analysis of over 200 foods was undertaken for the purpose of determining the variability in trans fatty acid content among foods within a product category, and the significance of this variability to the estimation of trans fatty acids intakes from analysis of dietary intake data. METHODS: The analysis of food fatty acids used gas-liquid chromatography with 100 m capillary columns and standardized methodologies for food sampling, fat extraction, separation and quantification of trans fatty acid isomers. For the purposes of this report, trans refers to all non-naturally occurring isomers including trans, cis-trans, geometric and positional isomers. RESULTS: The results show that the amount of trans fatty acids varies considerably among foods within a category, reflecting differences in the fats and oils used in the manufacturing or preparation process. For example, the range of trans fatty acids in 17 brands of crackers was 23 to 51% total fatty acids, representing differences of from 1 to 13 g trans fatty acids per 100 g cracker. The large errors that may arise in estimates of the trans fatty acid intake of an individual are illustrated by analyses of the potential trans fatty acid intake in a sample diet, for each food as calculated using the minimum and maximum values for trans fatty acids within a given category. The results of these analyses show estimates of trans fatty acid intake from a low of 1.4 to 25.4 g a day for the same diet. CONCLUSION: This study shows that the wide variability in trans fatty acid content of different foods may result in large errors in the estimation of trans fatty acid intake of individuals and, potentially, groups.     

Fatty acid composition of prepared infant formulas

The fatty acid composition of eight American, eight European, and four Japanese prepared infant formulas were determined and compared with fat sources listed on labels. Unsaturated fatty acids ranged from 20 to 83 per cent of the total. Generally, the fatty acid composition was consistent with the types of ingredients used; those with corn or soy oil had the highest levels of unsaturated fat, and those with milk fat the lowest; formulas of mixed composition fell in between. The formulas were compared with values for the fatty acid composition of human milk in the literature.     

Linoleate enrichment of diet and prostaglandin metabolism in rats.

Evidence that biosynthesis of prostaglandins (PG) in tissues of animals deficient in essential fatty acids is dependent on the availability of their precursors has been demonstrated. The purpose of this study was to determine the following: (1) effects of dietary linoleate enrichment on PG biosynthesis in rats; (2) effects of exogenous PGE2 and dietary linoleate on plasma free fatty acids and serum cholesterol in fed and fasted rats. Rats were fed three different concentrations of dietary linoleate as beef tallow, hydrogenated vegetable fat, or corn oil. The concentrations of PGE1 and PGF2a measured by radioimmunoassay were higher in rats fed the fed the beef tallow diet independent of energy status. A decrease in the concentration of PG between fasted and fed rats receiving hydrogenated vegetable fat is discussed in respect to the possible influence of trans isomers of unsaturated fatty acids on the biosynthesis of PG. There were significant effects of fasting on serum cholesterol concentration regardless of diet and significant interactions among effects of PGE2, fasting, and diet, suggesting regulatory effects of PGE2 on serum cholesterol concentration. The increase in plasma free fatty acids associated with fasting was prevented by PGE2 for all diets, but had the most marked effect on rats fed hydrogenated vegetable fat.     

Linoleic acid lowers LDL cholesterol without a proportionate displacement of saturated fatty acid

We tested the specificity of the plasma cholesterol-lowering effect of linoleic acid in a comparison of linoleate-rich and saturated fatty acid-rich foods. Twelve mildly hypercholesterolemic men and women ate the two diets for three weeks each in a random cross-over design, after a two-week baseline period. A linoleic acid-rich supplement was added to the baseline diet so that the saturated and monounsaturated fatty acid content did not change significantly. Despite the consequent increase in total fat intake, the linoleate-rich diet (23 per cent energy from polyunsaturated fatty acids) significantly lowered plasma total and low-density lipoprotein (LDL) cholesterol (-8 per cent and -14 per cent respectively), while high-density lipoprotein (HDL) cholesterol rose 8 per cent. The direction of these changes was similar in all 12 subjects. Compared with a supplement that raised dietary saturated fatty acids to 30 per cent energy, the linoleate acid-rich diet gave lower total cholesterol (-14 per cent), LDL cholesterol (-18 per cent) and HDL cholesterol (-12 per cent) concentrations. Linoleic acid lowers LDL cholesterol even when saturated fatty acids are not significantly displaced and substantially more when there is such displacement.     

Fatty acid composition of human milk in Western Iran

OBJECTIVE: To investigate the fatty acid composition of mature human milk in Western Iran with special focus on trans fatty acids. DESIGN: Observational study. METHODS: Milk samples were collected from 52 lactating mothers aging 19-39 y, from Western Iran. Subjects were asked to complete a diet questionnaire. Milk fatty acids were measured as 2-nitrophenylhydrazide derivatives by high-performance liquid chromatography. RESULTS: Saturated fatty acids were the main fraction of human milk (41.3%). Medium-chain fatty acids (C8:0-C14:0) constituted 24%, oleic acid (C18:1omega9) accounted for 30.9% and elaidic acid (C18:1T), the trans isomer of oleic acid, comprised 11.3% of the total milk fatty acids. Linoleic (C18:2omega6) and linolenic (C18:3omega3) acid contents were 13.8 and 1.1%, respectively. The level of the polyunsaturated fatty acids was 1.4% for arachidonic (C20:4omega6) and 0.2% for eicosapentaenoic (C20:5omega3) acid. CONCLUSIONS: The milk from Iranian lactating mothers, as compared to that from the American or European mothers, contained high levels of medium-chain and trans fatty acids. This difference may be attributed to the maternal diet with low animal protein and animal fat but with high carbohydrate and partially hydrogenated vegetable oils that carry large amounts of trans fatty acids. As the detrimental effects of trans fatty acids on blood lipids and cardiovascular diseases have been emphasized in the literature, a reduction of trans fatty acid content in the diet of Iranian mothers is suggested. SPONSORSHIP: Kermanshah University of Medical Sciences.     

trans Fatty acids in human milk are inversely associated with concentrations of essential all-cis n-6 and n-3 fatty acids and determine trans, but not n-6 and n-3, fatty acids in plasma lipids of breast-fed infants.

BACKGROUND: Human milk fatty acids vary with maternal dietary fat composition. Hydrogenated dietary oils with trans fatty acids may displace cis n-6 and n-3 unsaturated fatty acids or have adverse effects on their metabolism. The effects of milk trans, n-6, and n-3 fatty acids in breast-fed infants are unclear, although n-6 and n-3 fatty acids are important in infant growth and development. OBJECTIVE: We sought to determine the relations between trans and cis unsaturated fatty acids in milk and plasma phospholipids and triacylglycerols of breast-fed infants, and to identify the major maternal dietary sources of trans fatty acids. DESIGN: We collected milk from 103 mothers with exclusively breast-fed 2-mo-old infants, blood from 62 infants, and 3-d dietary records from 21 mothers. RESULTS: Mean (+/-SEM) percentages of trans fatty acids were as follows: milk, 7.1 +/- 0.32%; infants' triacylglycerols, 6.5 +/- 0. 33%; and infants' phospholipids, 3.7 +/- 0.16%. Milk trans fatty acids, alpha-linolenic acid (18:3n-3), arachidonic acid (20:4n-6), docosahexaenoic acid (22:6n-3) (P < 0.001), and linoleic acid (18:2n-6) (P = 0.007) were each related to the same fatty acid in infant plasma phospholipids. Milk trans fatty acids were inversely related to milk 18:2n-6 and 18:3n-3, but not to milk or infant plasma 20:4n-6 or 22:6n-3. trans Fatty acids represented 7.7% of maternal total fat intake (2.5% of total energy); the major dietary sources were bakery products and breads (32%), snacks (14%), fast foods (11%), and margarines and shortenings (11%). CONCLUSIONS: There were comparable concentrations of trans fatty acids in the maternal diet, breast milk, and plasma triacylglycerols of breast-fed infants. Prepared foods were the major dietary source of trans fatty acids.     

Home use of margarine is an important determinant of plasma trans fatty acid status: a biomarker study

The contribution of the home use of margarines, made with partially hydrogenated vegetables oils, to total trans fatty acid intake is difficult to determine using dietary assessment because food composition databases are incomplete for trans fatty acids; moreover, hidden fats in manufactured foods may be the predominant sources of trans fatty acids. The objective of our study was to determine, using plasma phospholipid trans fatty acid composition as a surrogate measure of exposure, whether the home use of margarine or butter is an important determinant of trans fatty acid status. We conducted a community-based (Dunedin, New Zealand), cross-sectional survey of people who consumed either margarine (n 65) or butter (n 64) but not both for home use. The levels of the 18:1 trans isomers commonly found in partially hydrogenated vegetable oils were all significantly higher in the plasma phospholipids of margarine compared with butter consumers, with the exception of 18:1n-7t, which did not differ. Among margarine consumers, the percentage of total fat from margarine was significantly correlated with levels of phospholipid 18:1n-6t, 18:1n-8t and 18:1n-12/9t isomers (r 0.57-0.63, P<0.001) but only weakly with 18:1n-7t (r 0.30, P=0.016). The intake of fat from fast foods, bakery products or meat and meat products was not associated with plasma phospholipid trans isomeric composition. The home use of margarine, made with partially hydrogenated vegetable oils, is an important determinant of trans fatty acid exposure in New Zealand.     

Comprehensive evaluation of fatty acids in foods. II. Beef products.

An estensive survey of the literature on lipids of beef covering the past fouteen years revealed that a number of factors, such as sex, age, and diet of animal, and analytical method, can affect the lipid content and fatty acid composition of beef. The feeding regimen of the animal was a factor considered in evaluating data for the food table. Extraction method was important in assessing information on lean tissue lipids. Statistical analysis showed that fatty acid patterns for the separable fat and separable lean of various meat cuts were not significantly different at the 5 per cent level. Cooking by dry or moist heat has little effect on relative fatty acid composition. Methods for converting methyl ester data into per cent composition of fatty acids in the meat cut are presented. A comprehensive table of fatty acids per 100 gm. separable lean, separable fet, and total edible portions of Choice grade cuts of beef is given, as well as a table acids per 100 gm. fat for lean and adipose tissues.     

Isomeric fatty acids in the US diet: levels and health perspectives

Data on market size, market share, and compositional changes of various products made from partially hydrogenated fats and oils were used to estimate current, previous, and predicted levels of trans fatty acids in the US diet. Recent literature and various perceptions of the toxicological, physiological, and nutritional effects of trans fatty acids were reviewed. Trans acid availability has changed little during the last 15-20 yr and currently is estimated to be approximately 7.6 g X person-1 X day-1. Modest decreases in total fat intake, including trans fatty acid intake, may occur in the future if consumers adopt certain dietary recommendations. We believe that concerns about possible relationships of trans fatty acids to development of atherosclerotic disease or cancer are not supported by reliable data. Numerous literature accounts support the conclusion that trans fatty acids do not pose any harm to humans or animals consuming a balanced diet containing adequate linoleic acid.     

Intensification of essential fatty acid deficiency in the rat by dietary trans fatty acids

Two studies were conducted using male rats to assess the effect of trans fatty acids upon essential fatty acid (EFA) deficiency. In the first study 5% corn oil (CO), hydrogenated coconut oil (HCNO) or margarine stock (MS, partially hydrogenated soybean oil) were fed, and the levels of trans fatty acids in tissue lipids were measured. The trans fatty acids present in MS were found to intensify EFA deficiency and to be retained in tissue lipids to a high degree, especially in heart phospholipids (PL). In the second study, as the level of trans fatty acids increased in the diet, increasingly higher levels of trans fatty acids were deposited in the heart PL. As dietary trans acid increased, a decrease in total omega 6 fatty acids, and a decrease in the sum of 18:2 omega 6 + 20:4 omega 6 - 20:3 omega 9 fatty acids in heart PL occurred, both criteria indicating a shift toward an increasing EFA deficiency state. Studies of delta 5 desaturase activity of liver microsomes in selected groups showed an increase in the conversion of 20:3 omega 6 to 20:4 omega 6 as the trans fatty acid level in the diet increased.     

Acute postprandial effect of hydrogenated fish oil, palm oil and lard on plasma cholesterol, triacylglycerol and non-esterified fatty acid metabolism in normocholesterolaemic males

The majority of research has focused on the association between trans unsaturated fatty acids (TUFA) from hydrogenated vegetable oils and heart disease even though TUFA are also produced from hydrogenated fish oil. We compared the acute effect of three solid fats on postprandial cholesterol, triacylglycerol (TAG) and NEFA concentrations in normocholesterolaemic males. Eight healthy male volunteers consumed each of the three 40 g fat meals (partially hydrogenated fish oil (PHFO), palm oil and lard) in random order and blood samples were drawn at 2, 4, 6 and 8 h thereafter for lipid analysis. The postprandial response in plasma TAG, TAG-rich lipoprotein-TAG (TRL-TAG), total cholesterol and plasma NEFA, measured as the area under the postprandial curve, was not significantly different between the three meals (P>0.05), which varied in MUFA, PUFA and TUFA content. There was no marked elevation of longer-chain fatty acids (C20-22, cis or trans isomers) into the TRL-TAG fraction following the PHFO meal even though they provided 40 % of the total fatty acids in the PHFO meal. The postprandial TRL-TAG response to PHFO was expected to be higher, as it is higher in TUFA, lower in PUFA and similar in saturated fatty acid composition compared with the lard and palm oil test meals. The absence of a higher postprandial response following ingestion of PHFO could be as a result of reduced absorption and increased oxidation of long-chain fatty acids (both cis and trans isomers).     

Body fat accumulation is greater in rats fed a beef tallow diet than in rats fed a safflower or soybean oil diet

The effects of dietary fats , consisting of different fatty acids, on body fat accumulation and uncoupling protein (UCP) in interscapular brown adipose tissue were studied in rats. Metabolisable energy in experimental diets based on safflower oil, soybean oil or beef tallow was measured strictly (experiment 1). Male Wistar rats were then meal-fed an isoenergetic diet for 8 weeks (experiment 2). Each group of rats showed the same weight gain during the 8-week experimental period. Carcass fat content was greater in rats fed the beef tallow diet than in those fed the with the safflower or soybean oil diets, whereas the weight of abdominal adipose tissue was the same for all three dietary groups. Gene expression of UCP1 and the UCP content of the interscapular brown adipose tissue was lower in the beef tallow diet group than in the other dietary groups. A negative correlation was observed between carcass fat content and n-6 unsaturated fatty acid content in dietary fats. These results suggest that the greater body fat accumulation in rats fed the beef tallow diet results from lower expression of UCP1 mRNA and lower UCP content in brown adipose tissue. n-6 Polyunsaturated fatty acids may be the most effective fatty acids in limiting body fat.     

Absorption of very-long-chain saturated fatty acids in totally hydrogenated fish oil

Partially hydrogenated fish oil (PHFO) contains a high amount of trans fatty acids (TFA). Total hydrogenation results in a minimal amount of TFA, but a high content of very-long-chain saturated fatty acids (VLCSFA). Absorption and metabolism of VLCSFA from totally hydrogenated fish oil (THFO) were studied in rats. Groups of eight rats were fed one of four diets containing 40 g soyabean oil (SBO)/kg (low-fat diet), 150 g SBO/kg (SBO diet), 40 g PHFO/kg (PHFO diet) or 40 g THFO/kg (THFO diet) for 4 weeks. A lower absorption coefficient of the fat content was found in the THFO group (61 %) compared with the other groups (PHFO 95 %, SBO 99 %, low fat 98 %; which was mainly due to reduced absorption of VLCSFA. A reduced weight gain was found for the THFO group compared with the other groups, but this was only significant when compared with the SBO group Faecal fat excretion (dry weight) was markedly increased in the THFO group (47 %), which was 2.4, 4.8 and 8.3 times higher compared with the groups fed PHFO, SBO and low-fat diets respectively. Serum total cholesterol was reduced for the PHFO and THFO groups whereas serum triacylglycerol was increased for the PHFO group compared with the other groups Animals fed THFO diet had an increased content of 20:0 and 22:0 in the serum triacylglycerol fraction whereas only 20:0 was increased in the serum phospholipid fraction The low absorption coefficient of THFO must be considered if this fat is to be used for consumption by animals or man.     

高脂饲料对OLETF大鼠糖代谢及血清磷脂脂肪酸组成的影响

目的:观察高脂饲料对自发性2型糖尿病模型OLETF大鼠糖代谢及血清磷脂脂肪酸组成的影响。方法:将20只14w雄性OLETF大鼠随机分为两组,分别以高脂及标准饲料喂饲10w,两种饲料中饱和脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸占总脂肪酸的百分含量相似。大鼠第24w龄时进行口服糖耐量试验,同时测定大鼠的胰岛素水平和血清磷脂脂肪酸组成。结果:实验期间两组大鼠总进食量无统计学差异,但高脂饲料组大鼠体重明显高于标准饲料组(P<0.01);口服糖耐量试验和胰岛素水平测定结果表明,两组大鼠的糖代谢状态无统计学差异;血清磷脂脂肪酸组成中,除总n-6PUFA和18:3(n-3)的百分含量无统计学差异外,其他各脂肪酸组分在两组间的差异均具有统计学意义(P<0.01)。结论:在饲料脂肪酸组成保持可比的情况下,饲料脂肪量的增加可使OLETF大鼠的体重明显增加,而对糖代谢的影响不明显,同时对OLETF大鼠血清磷脂脂肪酸组成产生明显影响。     

Total fat intake modifies plasma fatty acid composition in humans

Plasma fatty acid composition reflects dietary fatty acids. Whether the total fat content of the diet alters the fatty acid composition of plasma phospholipid, cholesteryl ester, triacylglycerol and free fatty acids is unknown. To evaluate the effects of low versus high fat diets on plasma fatty acids, a 12-wk, randomized, crossover, controlled feeding trial was conducted in healthy men and women with isoenergic low fat (20% energy) and high fat (45% energy) diets containing constant proportions of fatty acids. Ten subjects consumed one experimental diet for 28 d, their usual diet for 4 wk and the alternate experimental diet for 28 d. Endpoint measures of plasma fatty acids were determined at the end of each experimental period. The effects of the two diets were compared within subjects by analysis of variance. Plasma fatty acids (%) varied in response to total dietary fat with significantly greater total polyunsaturated fat, (n-6) and 18:2(n-6) levels in phospholipids and cholesteryl esters after high fat dietary consumption. The low fat diet was associated with significantly greater total (n-3) fatty acids, 20:5(n-3) and 22:6(n-3) levels in plasma phospholipid fatty acids and cholesteryl esters. Consumption of a low fat diet alters fatty acid patterns in a manner similar to that observed with feeding of (n-3) long-chain fatty acids. This change is likely related to decreased competition for the enzymes of elongation and desaturation, with reduced total intake of 18:2(n-6) favoring elongation and desaturation of available (n-3) fatty acids.     

Dietary hydrogenated soybean oil affects lipid and vitamin E metabolism in rats

Fatty acids containing stearic acid, which are found in hydrogenated fat, may have a detrimental effect on the cholesterol and triacylglycerol (TAG) content of plasma lipoproteins, and on the absorption of fatty acids and fat-soluble vitamins. The aim of our study was to examine the tissue concentration of lipids and vitamins A and E after feeding a hydrogenated soybean oil (HSO) diet to rats. Twenty male Sprague-Dawley rats were randomly divided into two groups, fed on coconut oil (control) and HSO, respectively in amounts corresponding to 15% of the total feed. Plasma total cholesterol, VLDL- and LDL-cholesterol, lipid peroxidation and daily excretion of the TAG and cholesterol in feces were higher in the HSO than in the control group. TAG values in plasma and liver, and HDL-cholesterol levels in plasma were lower in the HSO than in the control group. The same was true for phospholipids in plasma and for saturated fatty acids, mono- and polyunsaturated fatty acids levels in the liver and vitamin E in plasma, LDL and adipose tissue. The results of this study provide new evidence concerning the effect of dietary hydrogenated fat on lipid, TAG and vitamin E status, which are important for maintenance of good health. Consumption of dietary HSO may be associated with cardiovascular disease.