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PubMed1998

[Trans-fatty acids and health].

Trans fatty acids are formed by partial hydrogenation of vegetable and marine oils or by bacterial activity in the rumen of ruminants. Main dietary sources are margarine, meat, milk fat and bakery products. Unsaturated fatty acids in the trans form have a more straight structure than their cis counterparts. They therefore have properties more like saturated fatty acids. Trans fatty acids may compete with essential fatty acids for elongating and desaturating enzymes and thereby interfere in the formation of eicosanoids. Trans fatty acids in the diet will increase LDL-cholesterol but to a lesser degree than the saturated fatty acids C12-C16. They also decrease HDL-cholesterol and increase Lp(a). By these unfavorable effects on blood lipids it may be expected that they will increase the risk of coronary heart disease. This has been confirmed in some, but not all, epidemiological studies. Provided the diet contains sufficient amounts of essential fatty acids there are no strong indications that trans fatty acids may have other unfavorable effects on health. Over time the intake of trans fatty acids has decreased considerably in Norway (from a mean of about 15 g/day in 1958 to about 4 g/day actually). The health effects of such an intake must be considered minor compared to an eight to ten fold higher intake of saturated fatty acids.

Blood Coagulation Factors↗
PubMed1998

Similar effects of diets rich in stearic acid or trans-fatty acids on platelet function and endothelial prostacyclin production in humans.

The effects of stearic acid (C18:0) and trans-fatty acids (trans-FAs) on measures of platelet function and prostacyclin (PGI2) production are poorly understood in humans. In this controlled dietary study, platelet function and endothelial PGI2 production were studied in healthy humans after they consumed diets rich in C18:0 or trans-FAs. For 5 weeks, 80 subjects consumed a baseline diet high in saturated FAs and were then switched to a diet containing 9.3% of energy as stearic acid or a diet containing 8.7 energy% as trans-FAs from hydrogenated vegetable oils for another 5 weeks. All diets contained 32.2 to 33.9 energy% fat, 14.6 to 15.8 energy% saturated plus trans-FAs, 12.2 to 12.5 energy% cis-monounsaturated, and 2.9 to 3.5 energy% polyunsaturated FAs. No significant differences between the C18:0 and trans-FA diets were found in the urinary excretion of 2,3-dinor-thromboxane B2 or 2,3-dinor-6-keto-prostaglandin F1alpha. In vitro production of thromboxane B2 by platelets as well as urinary excretion of beta-thromboglobulin were also similar after both diets. Collagen-induced in vitro aggregation was significantly enhanced after the C18:0 diet compared with the trans-FA diet (P=.02), whereas no differences between the diets were found with ADP. The results indicate similar effects of C18:0 and trans-FA diets on platelet activation and endothelial PGI2 production.

Adult↗
PubMed1994

Is insulin resistance influenced by dietary linoleic acid and trans fatty acids?

The incidence of obesity, noninsulin-dependent diabetes mellitus (NIDDM), hypertension, and coronary artery disease has increased in the developed world. At the same time, major changes in the type and amount of fatty acid intake have occurred over the past 40-50 years, reflected in increases in saturated fat (from both animal sources and hydrogenated vegetable sources), trans fatty acids, vegetable oils rich in linoleic acid, and an overall decrease in long chain polyunsaturated fatty acids (arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid--C20-C22). Recent findings that C20-C22 in muscle membrane phospholipids are inversely related to insulin resistance, whereas linoleic acid is positively related to insulin resistance, suggest that diet may influence the development of insulin resistance in obesity, insulin-dependent diabetes mellitus (IDDM), hypertension, and coronary artery disease (including asymptomatic atherosclerosis and microvascular angina). These conditions are known to have genetic determinants and have a common abnormality in smooth muscle response and insulin resistance. It is proposed that the current diet influences the expression of insulin resistance in those who are genetically predisposed. Therefore, clinical investigations are needed to evaluate if lowering or preventing insulin resistance through diet by increasing arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, while lowering linoleic acid and decreasing trans fatty acids from the diet, will modify or prevent the development of these diseases.

Animals↗
PubMed1993

Effects of stearic acid and trans fatty acids versus linoleic acid on blood pressure in normotensive women and men.

The objective of this study was to compare the effect of linoleic acid (cis,cis-C18:2) with that of its hydrogenation products stearic acid (C18:0) and elaidic acid (trans-C18:1) on blood pressure levels in normotensive humans. We therefore measured the effects of these fatty acids on systolic and diastolic blood pressure in 30 women and 25 men. Three strictly controlled experimental diets were supplied to every subject for 3 weeks each, in different order (multiple cross-over). The composition of the three diets was constant, except for 8% of daily energy, which was provided by either linoleic acid, stearic acid, or monounsaturated trans fatty acids. The statistical power for detecting a true difference between two diets of 3 mmHg in systolic and diastolic blood pressure was over 90%. Mean systolic/diastolic blood pressure at the end of the dietary periods was 114/69 mmHg on the linoleic acid diet, 113/70 on the stearic acid diet, and 113/69 on the trans fatty acid diet. No significant differences were observed in blood pressure levels after 3 weeks on each diet. We conclude that a major increase in the intake of linoleic acid at the expense of stearic acid or trans fatty acids has no effect on blood pressure in normotensive young women and men.

Adult↗
PubMed1996

Fatty acid composition of Danish margarines and shortenings, with special emphasis on trans fatty acids.

Trans fatty acids from hydrogenated vegetable and marine oils could be as hypercholesterolemic and atherogenic as saturated fatty acids. Hence, it is important to know the fatty acid composition in major food contributors, e.g., margarines and shortenings. In 1992 margarines were examined, and in 1995 brands covering the entire Danish market were examined. Significant amounts of trans-18:1 were found only in hard margarines (mean: 4.2 +/- 2.8%) and shortenings (mean: 6.8 +/- 3.1%), whereas the semisoft and soft margarines contained substantially less trans-18:1 in 1995 than in 1992. Where marine oils had been used to a larger degree the mean trans-monoenoic content was about 15%, of which close to 50% was made up of long-chain (C20 and C22) trans fatty acids. A noteworthy decrease in the content of trans-18:1 had occurred for the semisoft margarines, from 9.8 +/- 6.1% in 1992 to 1.2 +/- 2.2% in 1995. Calculated from sales figures, the supply of trans-18:1 plus saturated fatty acids from margarines has decreased over this three-year period by 1.4 g/day, which has been replaced by cis monounsaturated and polyunsaturated fatty acids.

Chromatography, Gas↗
PubMed1994

[Significance of trans-fatty acids for health].

Trans fatty acids make up 0-30% of the fatty acids in Danish margarines. The intake of trans fatty acids from margarine in Denmark was in 1991 on average about 2.5 gram/person/day, and for about 150,000 Danes more than 5 gram/person/day. Several recent case-control studies and a large cohort study as well as clinical ward studies suggest that the intake of trans fatty acids enhances atherogenesis to the same extent or possibly even more than saturated fatty acids. In addition a few studies suggest that the intake of trans fatty acids by the pregnant mother impairs growth of the human foetus. On this background it seems reasonable to reduce the intake of trans fatty acids as much as possible. This could be implemented by a reduction in the fat content of the diet together with a reduction of trans fatty acid content to less than 5% in all margarines. This would ensure that Danes--including pregnant and nursing women--with a high intake of margarine on average consume less than 2 gram of trans fatty acids of vegetables origin per day. This amount corresponds to intake in low risk groups in several studies.

Denmark↗
PubMed1992

Hydrogenation alternatives: effects of trans fatty acids and stearic acid versus linoleic acid on serum lipids and lipoproteins in humans.

The objective of this study was to compare the effects of linoleic acid (cis,cis-C18:2(n-6)) and its hydrogenation products elaidic (trans-C18:1(n-9)) and stearic acid (C18:0) on serum lipoprotein levels in humans. Twenty-six men and 30 women, all normolipemic and apparently healthy, completed the trial. Three experimental diets were supplied to every subject for 3 weeks each, in random order (multiple cross-over). The Linoleate-diet provided 12.0% of total energy intake as linoleic acid, 2.8% as stearic acid, and 0.1% as trans fatty acids. The Stearate-diet supplied 3.9 energy % as linoleic acid, 11.8% stearic acid, and 0.3% trans fatty acids. The Trans-diet provided 3.8 energy % as linoleic acid, 3.0% stearic acid, and 7.7% as monounsaturated trans fatty acids, largely elaidic acid (trans-C18:1(n-9)). Other nutrients were constant. Fasting blood was sampled at the end of each dietary period. Mean (+/- SD) serum LDL cholesterol was 109 +/- 24 mg/dl (2.83 +/- 0.63 mmol/l) on the Linoleate-diet. It rose to 116 +/- 27 mg/dl (3.00 +/- 0.71 mmol/l) on the Stearate-diet (change, 7 mg/dl or 0.17 mmol/l, P = 0.0008) and to 119 +/- 25 mg/dl (3.07 +/- 0.65 mmol/l) on the Trans-diet (change, 9 mg/dl or 0.24 mmol/l, P less than 0.0001). High density lipoprotein (HDL) cholesterol decreased by 2 mg/dl (0.06 mmol/l, P less than 0.0001) on the Stearate-diet and by 4 mg/dl (0.10 mmol/l, P less than 0.0001) on the Trans-diet, both relative to linoleic acid. Our findings show that 7.7% of energy (mean, 24 g/day) of trans fatty acids in the diet significantly lowered HDL cholesterol and raised LDL cholesterol relative to linoleic acid. Combination with earlier results (Mensink, R. P., and M. B. Katan. 1990. N. Engl. J. Med. 323: 439-445) suggests a linear dose-response relation. Replacement of linoleic acid by stearic acid also caused somewhat lower HDL cholesterol and higher LDL cholesterol levels. Hydrogenation of linoleic acid to either stearic or trans fatty acids produces fatty acids that may increase LDL and decrease HDL cholesterol relative to linoleic acid itself.

Adolescent↗
PubMed1995

Trans fatty acids and coronary heart disease risk. Report of the expert panel on trans fatty acids and coronary heart disease.

This review critically evaluates the scientific data on trans fatty acids and coronary heart disease (CHD) risk. Trans fatty acids are present in a variety of foods but they contribute only 4-12% of total dietary fat intake (2-4% of total energy intake) in the United States. The physical properties of trans fatty acids are intermediate between cis and saturated fatty acids, but a trans double bond is chemically less reactive than a cis double bond. Biochemical data indicate that trans fatty acids are subject to the same metabolic control mechanisms that regulate the metabolism of saturated and cis-isomeric fatty acids. Equivocal results have been reported in observational studies of trans fatty acid intake and CHD because of numerous methodologic limitations, including the difficulties inherent in quantifying trans fatty acid intake. Studies in hamsters indicate that trans fatty acids have a neutral effect on low-density-lipoprotein (LDL)-receptor activity, LDL-cholesterol production rate, and plasma LDL-cholesterol concentration. Other animal studies show no differences in atherosclerosis incidence or severity between diets containing hydrogenated and native vegetable oils. In clinical studies partially hydrogenated oils lower total and LDL-cholesterol concentrations when substituted for animal or vegetable fats rich in saturates but raise total and LDL-cholesterol concentrations when substituted for the unhydrogenated native oil. The effects of trans fatty acids on high-density lipoprotein cholesterol and lipoprotein(a) concentrations are unclear because of limited and conflicting clinical data. Data supporting a relation between trans fatty acid intake and CHD risk are equivocal compared with extensive data from studies in animals and humans linking saturated fat intake to CHD. Additional research is needed to resolve questions about the independent effects of trans fatty acids on plasma lipoproteins and their mechanisms of action.

Animals↗
PubMed1999

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.

Canada↗
PubMed2005

Effect of heating and processing methods of milk and dairy products on conjugated linoleic acid and trans fatty Acid isomer content.

The conventional heating methods of milk did not cause any significant increase in the trans isomer content, with the exception of milk heated at 63 +/- 1.0 degrees C for 30 min and milk microwaved for 5 min, which were significantly increased by 19 and 31%, respectively. The chemical changes of lipids were generally accelerated with the severity of the heat treatment and duration of storage. The conjugated linoleic acid content of cheese heated in a microwave oven for 5 min decreased by 21%, and microwave heating for 10 min caused a decrease of 53% compared with that of freshly boiled cheese.

Animals↗
PubMed1994

Feeding trans fatty acids to rats has no effect on the intestinal uptake of glucose, fatty acids or cholesterol.

Trans fatty acids are produced in the manufacture of margarine, and these hydrogenated fatty acids may have a deleterious effect on the reduction in fasting levels of serum cholesterol anticipated from the feeding of cis polyunsaturated fatty acids. We undertook this study in rats to test the effect of feeding trans fatty acids on the intestinal uptake of glucose, fatty acids and cholesterol. Adult female Wistar rats were fed for 2 weeks semisynthetic, isocaloric diets containing no oleic acid (18:1), cis 18:1 or trans 18:1. There was no difference between the three dietary groups in the animals' food consumption or body weight gain. Rats fed trans 18:1 had an approximately 20% decline in the total weight of the ileum as compared with controls fed no 18:1, and therefore there was also a decline in the percentage of the ileal tissue comprised of mucosa. When comparing rats fed trans 18:1 with those fed cis 18:1 or no 18:1, there was no difference in the uptake of varying concentrations of D-glucose when expressed as nmol.100 mg tissue-1.min-1 or nmol.100 mg mucosal-1.min-1 for jejunum or for ileum. Also, there was no difference in the value of the maximal transport rate (Vmax), Michaelis constant (Km), or the contribution of passive uptake of glucose assessed with L-glucose. There was no diet-associated change in the jejunal or ileal uptake of a medium-chain length fatty acid (lauric acid), a long-chain length saturated fatty acid (palmitic acid), a monounsaturated fatty acid (oleic acid), two polyunsaturated fatty acids (linoleic and linolenic acids), or cholesterol. Thus, we conclude that 2 weeks' feeding of trans fatty acid to rats has no influence on the jejunal or ileal uptake of glucose, fatty acids or cholesterol.

Absorption↗
PubMed1999

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.

Breast Feeding↗
PubMed1979

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.

Animals↗
PubMed1988

Linoleic acid requirement of rats fed trans fatty acids.

The amount of linoleic acid required to prevent undesirable effects of C18 trans fatty acids was investigated. In a first experiment, six groups of rats were fed diets with a high content of trans fatty acids (20% of energy [en%]), and increasing amounts of linoleic acid (0.4 to 7.1 en%). In a second experiment, four groups of rats were fed diets designed to compare trans fatty acids with saturated and cis-monounsaturated fatty acids of the same chain length at the 2 en% linoleic acid level. After 9-14 weeks, the oxygen uptake, lipid composition and ATP synthesis of heart and liver mitochondria were determined. The phospholipid composition of the mitochondria did not change, but the fatty acid compositions of the two main mitochondrial phospholipids were influenced by the dietary fats. Trans fatty acids were incorporated in all phospholipids investigated. The linoleic acid level in the phospholipids, irrespective of the dietary content of linoleic acid, increased on incorporation of trans fatty acids. The arachidonic acid level had decreased in most phospholipids in animals fed diets containing 2 en% linoleic acid. At higher linoleic acid intakes, the effect of trans fatty acids on the phospholipid arachidonic acid level diminished. However, in heart mitochondrial phosphatidylethanolamine, trans fatty acids significantly increased the arachidonic acid level. Despite these changes in composition, neither the amount of dietary linoleic acid nor the addition of trans fatty acids influenced the mitochondrial function. For rats, a level of 2 en% of linoleic acid is sufficient to prevent undesirable effects of high amounts of dietary C18 trans fatty acids on the mitochondrial function.

Animals↗
PubMed2004

Short communication: Diurnal profiles of conjugated linoleic acids and trans fatty acids in ruminal fluid from cows fed a high concentrate diet supplemented with fish oil, linseed oil, or sunflower oil.

Trans-18:1 and 18:2 isomer composition in ruminal fluid during the daily feeding cycle was examined in 3 cows fed a high concentrate diet (35:65) with 5% (DM basis) sunflower oil (SO), 5% linseed oil (LO), or 2.5% fish oil (FO) in a 3 x 3 Latin square with 3 4-wk periods. Grass hay and concentrate mixtures were fed at 0900, 1300, and 1700 h daily. Ruminal fluid was collected at 0900, 1100, 1300, 1500, 1700, 2000, and 0000 h. Feeding SO resulted in the greatest mean concentrations (% of total fatty acids) of trans10,cis12-18:2 and cis9,trans11-18:2. In particular, trans10,cis12-18:2 with SO was greater at 1500 (0.29%), 2000 (0.34%), and 0000 h (0.25%) relative to 0900 h (0.07%). Cis9,trans11-18:2 concentration increased from 0.47% at 0900 h to a peak of 2.06% at 1100 h; it remained greater than the percentage determined at 0900 h at 1300 (1.4%) through 0000 h (1.1%). Concentration of trans11,cis15-18:2 was greatest with LO, ranging from 3.3% (0900 h) to a peak of 11.4% at 2000 h. Mean trans10-18:1 concentration ranked by diet was SO > FO > LO. Peak trans10-18:1 with SO was observed at 1700 h (14.9%) compared with 0900 h (5.1%). Trans11-18:1 did not differ with diet or time. Stearic acid decreased over time with all diets reaching minimum concentrations at 1700 to 2000 h relative to 0900 h. Feeding FO, however, decreased mean 18:0 concentration 4-fold compared with LO or SO. The moderate effect on concentration of trans-18:1 coupled with accumulation of 18:2 intermediates and the decrease of 18:0 over time suggest that oils reduced the biohydrogenation of 18:2 isomers to trans-18:1.

Animals↗
PubMed1998

Assessment of trans-fatty acid intake with a food frequency questionnaire and validation with adipose tissue levels of trans-fatty acids.

Past studies of the association of trans-fatty acid intake with coronary heart disease have been hindered by the lack of a database on the trans-fatty acid content of various foods. The authors used new data from the US Department of Agriculture to estimate trans-fatty acid intake using a self-administered food frequency questionnaire (FFQ), and they assessed the validity of the FFQ by comparing the dietary estimates with trans-fatty acid concentrations in adipose tissue. The 1996 study included 27 women and 24 men aged 51-78 years. The mean consumption of total trans-fatty acids estimated from the FFQ was 2.24 g per day and 5% of total dietary fat. The mean concentration of total trans-fatty acids in buttock adipose tissue was 4.7% of total fatty acids. Pearson correlations between total dietary intake of trans-fatty acids and total trans-fatty acid levels in adipose tissue were 0.67 (95% confidence interval (CI) 0.36-0.84) among men and 0.58 (95% CI 0.26-0.79) among women. After adjustment for energy intake, age, and body mass index, the correlation coefficients were 0.76 (95% CI 0.51-0.89) among men and 0.52 (95% CI 0.17-0.75) among women. The FFQ validated in this study is an important new tool for assessing usual intake of trans-fatty acids.

Adipose Tissue↗
PubMed2004

Conjugated linoleic acid isomers and trans fatty acids inhibit fatty acid transport in hepatoma 7288CTC and inguinal fat pads in Buffalo rats.

Conjugated linoleic acid (CLA) and some trans fatty acids (FA) decrease tumor growth and alter tumor and host lipid uptake and storage. The goal of this study was to test the hypothesis that the acute inhibitory effects of CLA isomers and trans FAs on FA transport in tumors and white adipose tissue are mediated via an inhibitory G-protein coupled (GPC), FFA receptor (FFAR). Experiments were performed in hepatoma 7288CTC and inguinal fat pads in Buffalo rats during perfusion in situ. CLA isomers and trans FAs (0.03-0.4 mmol/L, in plasma) were added to the arterial blood, and FA uptake or release was measured by arterial minus venous difference. In hepatoma 7288CTC, the CLA isomers, t10,c12-CLA > (+/-)-9-HODE [13-(S)-hydroxyoctadecadienoic acid] > t9,t11-CLA, and the trans FAs, linolelaidic = vaccenic > elaidic, decreased cAMP content and inhibited FA uptake, 13(S)-HODE release, extracellular signal-regulated kinase p44/p42 phosphorylation, and [(3)H]thymidine incorporation. Other CLA isomers, c9,t11-CLA, 13-(S)-HODE, c9,c11-CLA, and c11,t13-CLA, had no effect. In inguinal fat pads, FA transport was inhibited by t10,c12-CLA = linolelaidic acid > trans vaccenic acid, whereas c9,t11-CLA had no effect. In both hepatoma 7288CTC and inguinal fat pad, addition of either pertussis toxin or 8-Br-cAMP to the arterial blood reversed the inhibitions of FA transport. These results support the idea that an inhibitory GPC FFAR reduces cAMP and controls FA transport by CLA isomers and trans FAs. Ligand activity is conferred by the presence of a trans double bond proximal to the carboxyl group.

Adipose Tissue↗