CLA differently regulates adipogenesis in stromal vascular cells from porcine subcutaneous adipose and skeletal muscle

Conjugated linoleic acid (CLA), a mixture of isomers of linoleic acid, has previously been shown to be able to decrease porcine subcutaneous (SC) adipose tissue levels while increasing the count of intramuscular (IM) adipose tissue in vivo. However, the underlying mechanisms through which it acts are poorly understood. The objective of this study was to investigate the different effects of CLA on adipogenesis in cultured SC adipose tissue and IM stromal vascular cells obtained from neonatal pigs. As shown here, trans-10, cis-12 CLA decreased the expression of adipocyte-specific genes as well as adipose precursor cell numbers and the accumulation of lipid in cultured SC adipose tissue stromal vascular cells. However, the cis-9, trans-11 CLA did not alter adipogenesis in SC cultures. On the other hand, both CLA isomers increased the expression of adipocyte-specific genes in IM cultures, together with the increasing accumulation of lipid and Oil Red O-stained cells. Collectively, these data show that CLA decreases SC adipose tissue but increases IM adipose tissue by different regulation of adipocyte-specific gene expression. These results suggest that adipogenesis in IM adipocytes differs from that in SC adipocytes.     

Selective production of cis-9,trans-11 isomer of conjugated linoleic acid from trans-vaccenic acid methyl ester by Delacroixia coronata

Aims:  Bio-process development for isomer selective and efficient production of cis -9, trans -11-octadecadienoic acid (CLA) from trans -vaccenic acid ( t -VA, trans -11-octadecenoic acid) through microbial fatty acid Δ9-desaturation reaction.
Methods and Results:  A total of 550 strains of fungi and yeasts were screened for CLA production from t -VA through Δ9 desaturation. Delacroixia coronata IFO 8586 was selected as a potent producer of CLA from t -VA. Efficient CLA production was observed during cultivation in medium supplemented with the methyl ester of t -VA ( t -VAME). Under the optimal conditions with 33·3 mg ml⁻¹ of t -VAME as substrate, 10·5 mg ml⁻¹ CLA was produced by D. coronata IFO 8586 after 7 days of cultivation in the medium containing dextrin (5·0%), tryptone (2·0%) and thiourea (0·83 μmol ml⁻¹). The strain produced the cis -9, trans -11 isomer of CLA selectively (98% of total CLA), with a small amount of the trans -9, trans -11 isomer (2% of total CLA), mainly in the form of triacylglycerols (69% of total CLA).
Conclusions:  A practical bio-process for selective production of cis -9, trans -11 isomer of CLA using filamentous fungus D. coronata IFO 8586 was successfully established.
Significance and Impact of the Study:  Isomer selective bio-process for the practical production of cis -9, trans -11-CLA was first established. The process is benefitable for expanding the application of CLA for medicinal and nutraceutical purposes.     

共轭亚油酸生理功能及微生物合成调控研究进展

共轭亚油酸(conjugated linoleic acid,CLA)是一种新型功能性油脂,顺9,反11-十八碳二烯酸(c9,t11-CLA)和反10,顺12-十八碳二烯酸(t10,c12-CLA)由于具有比其他异构体更强的生理功能得到广泛关注和研究.微生物合成CLA具有安全性高、选择特异性强等特点,研究CLA产量提高...     

Effect of silage type and concentrate level on conjugated linoleic acids, trans-C18:1 isomers and fat content in milk from dairy cows

The objective of the study was to examine how the fatty acid composition of milk especially concentrations of conjugated linoleic acids (CLA) and trans-C18:1 isomers and milk fat percentage were affected by silage type and concentrate level. Forty dairy cows were blocked and randomly assigned to one of four diets in a 2 x 2 factorial arrangement of treatments and a six week experimental period. Treatments were total mixed rations with maize (M) or grass (G) silage differing in polyunsaturated fatty acid (PUFA) profile and starch content, combined with a high (H) or a low (L) level of concentrate (with or without grain). Treatments had no significant effect on milk, protein and lactose yield, but energy corrected milk yield, milk fat percentage and fat yield was lower and protein percentage higher for maize compared with grass silage diets. Overall, maize silage diets resulted in higher concentrations of CLA isomers compared with grass silage diets, but there was a significant interaction between silage type and concentrate level for concentrations of cis9,trans11-CLA; trans10,cis12-CLA; trans11-C18:1 and trans10-C18:1. A high level of concentrate increased trans10,cis12-CLA and trans10-C18:1 and reduced cis9,trans11-CLA and trans11-C18:1 when maize but not grass silage was provided. The results suggest that high levels of concentrate (grain) do not significantly alter the pattern of PUFA biohydrogenation in the rumen, the concentration of CLA and trans-C18:1 isomers in milk or cause milk fat depression unless combined with forage naturally high in starch and C18:2n-6 such as maize silage.     

The effect of conjugated linoleic acid on arachidonic acid metabolism and eicosanoid production in human saphenous vein endothelial cells

The effects of a conjugated linoleic acid (CLA) mixture of single isomers (50:50, w/w, cis9,trans11:trans10,cis12) and the individual isomers on (a) the production of resting and calcium ionophore stimulated (14)C-eicosanoids and (b) the incorporation of (14)C-arachidonic acid (AA) into membrane phospholipids of human saphenous vein endothelial cells were investigated. The CLA mixture and the individual isomers were found to inhibit resting production of (14)C-prostaglandin F(2a) by 50, 43 and 40%, respectively. A dose dependent inhibition of stimulated (14)C-prostaglandins was observed with the CLA mixture (IC(50) 100 microM). The cis9,trans11 and trans10,cis12 (50 microM) isomers individually inhibited the overall production of stimulated (14)C-prostaglandins (between 35 and 55% and 23 and 42%, respectively). When tested at a high concentration (100 microM), cis9,trans11 was found to inhibit eicosanoid production in contrast to trans10,cis12 that caused stimulation. The overall degree of (14)C-AA incorporation into membrane phospholipids of the CLA (mixture and individual isomers) treated cells was found to be lower than that of control cells and the cis9,trans11 isomer was found to increase the incorporation of (14)C-AA into phosphatidylcholine. Docosahexaenoic acid, eicosapentaenoic acid and linoleic acid did not alter the overall degree of incorporation of (14)C-AA. The results of this study suggest that both isomers inhibit eicosanoid production, and although trans10,cis12 exhibits pro-inflammatory activity at high concentrations, the CLA mixture maintains its beneficial anti-inflammatory action that contributes to its anti-carcinogenic and anti-atherogenic properties.     

Prolonged feeding of mice with conjugated linoleic acid increases hepatic fatty acid synthesis relative to oxidation

Feeding mice conjugated linoleic acid (9 cis,11 trans/9 trans,11 cis-and 10 trans,12 cis-CLA in equal amounts) resulted in triacylglycerol accumulation in the liver. The objective of this study was to examine whether this steatosis is associated with changes in hepatic fatty acid synthesis and oxidation. Therefore, we measured the activities of key enzymes of fatty acid synthesis, i.e., acetyl-CoA carboxylase and fatty acid synthase and of fatty acid oxidation, i.e., 3-hydroxy-acyl-CoA dehydrogenase and citrate synthase in livers of mice fed a diet with 0.5% (w/w) CLA. CLA (a 1:1 mixture of the 10 trans, 12 cis and 9 cis, 11 trans isomers of octadecadenoic acid) was administered for 3 and 12 weeks with high-oleic sunflower oil fed as control. The proportion of body fat was significantly lower on the CLA than on the control diet and this effect was already significant after 3 weeks. The specific activites of 3-hydroxy-acyl-CoA dehydrogenase and citrate synthase were unaffected by CLA both after 3 and 12 weeks. The specific activity of fatty acid synthase was nonsignificantly raised (by 12%) after 3 weeks on the CLA diet but had increased significantly (by 34%) after 12 weeks of feeding. The specific activity of acetyl-CoA carboxylase had also increased both after 3 weeks (by 53%) and 12 weeks (by 23%) on the CLA diet, but this effect did not reach statistical significance. Due to CLA-induced hepatomegaly, the overall capacity for both fatty acid oxidation and synthesis-as evidenced by the total hepatic activities of 3-hydroxy-acyl-CoA dehydrogenase, citrate synthase, acetyl-CoA carboxylase, and fatty acid synthase-was significantly greater in the CLA-fed group after 12 weeks, although the overall capacity for fatty acid synthesis had increased more than that for fatty acid oxidation. Thus, this study indicates that prolonged, but not short-term, feeding mice with CLA increased hepatic fatty acid synthesis relative to oxidation, despite the decrease in body fat and the increase in liver weight seen earlier. It is concluded that the observed CLA-induced changes in hepatic fatty acid synthesis and oxidation are the result, rather than the cause, of the lowering of body fat.     

Conjugated linoleic acid metabolism

Conjugated linoleic acid (CLA) is a naturally occurring fatty acid that is produced by a bio-hydrogenation process in the rumen, and thus is present in dairy products and ruminant meat. In this case the predominant isomer formed is 9cis,11trans. However, CLA includes 28 positional and geometrical isomers, of which only 9cis,11trans and 10trans,12cis have thus far been proven to possess biological activities. Both of these CLA isomers have been shown to undergo elongation and desaturation processes similar to those that occur with linoleic acid, maintaining the conjugated diene structure. There are evidences supporting the hypothesis that CLA metabolism may interfere with eicosanoid formation. Other metabolites with 16 carbon atoms (conjugated 16:2 and 16:3, which are probably derived from peroxisomal beta-oxidation of CLA and its metabolites, respectively) have been detected. This suggests an efficient metabolism of CLA and its metabolites in peroxisomes, which might be linked to their capacity to activate peroxisome proliferator-activated receptors.     

Effect of chestnut and quebracho tannins on fatty acid profile in rumen liquid- and solid-associated bacteria: an in vitro study

Tannins are phenolic compounds that interfere with biohydrogenation (BH) of polyunsaturated fatty acids (FAs). The aim of the present in vitro study was to investigate the effects of two different sources of tannins on FA profiles of rumen bacteria, with particular reference to rumenic and vaccenic acid. A control diet (C; composed of 300 g/kg of wheat straw, 132 g/kg of soyabean meal, 96 g/kg of barley meal, 152 g/kg of maize meal, 300 g/kg of maize gluten and 20 g/kg of mineral vitamin premix, all expressed on dry matter (DM)) and four diets, obtained by adding to C two different types of tannins from chestnut (TC) and from quebracho (TQ) at two concentration levels (49 and 82 g/kg DM), were compared. The content of the main unsaturated FAs (C18:1 cis9, C18:1 trans11, C18:2 cis9, cis12 and C18:3 cis9, cis12, cis15) from solid-associated bacteria (SAB) and liquid-associated bacteria (LAB) was affected by the presence of tannins in the diets. In particular, C18:1 trans11 content was significantly increased, especially with TC1, whereas the decreasing of C18:1 cis9 was unaffected, regardless of the presence or the kind of tannins added to feeds. SAB contained higher amounts of intermediates of polyunsaturated FA BH (as C18:1 trans11 and C18:2 cis9, trans11) than LAB that were characterized by a higher amount of C18:0. In the concentration range adopted in this study, the effect of TC and TQ on changes of bacterial FA profile was comparable. Tannins seem to be a good means to modulate the FA profile of rumen bacteria, favouring the accumulation of C18:1 trans11 during in vitro rumen fermentation.     

Modulation of lipid metabolism and vitamin A by conjugated linoleic acid

The term conjugated linoleic acid (CLA) refers to a collection of positional and geometrical isomers of octadeca- dienoic acid with conjugated double bonds. CLA has been shown to possess several beneficial activities in different experimental models, however, out of 28 isomers only two, c9, t11 and t10, c12 have been thus far demonstrated to be biologically active.The discovery that it can be elongated and desaturated as a regular fatty acid in human and animal tissues brought a new possibility that its activity may be related to its properties as a peculiar unsaturated fatty acid. In fact, CLA is able to be incorporated in lipid classes as oleic acid, accumulating in those tissues rich in neutral lipids; to be metabolized as linoleic acid and so influencing linoleic acid desaturation and elongation; and to be beta oxidized in peroxisomes which may account for, through activation of PPARs, its ability to increase free retinol levels and influence gene expression. These activities are amplified where CLA accumulates more such as mammary and adipose tissues and may explain its peculiar beneficial properties, at relative low dietary concentrations, in these tissues. Furthermore, it has been demonstrated that CLA can be endogenously formed by delta 9 desaturation of vaccenic acid (t11 18:1) thus forming the isomer c9, t11. Either endogenously formed or through dietary intake, CLA showed to be metabolized in the same way and to exert the same biological properties. We may conclude that a regular intake of CLA, or/and vaccenic acid as its precursor, should work as an excellent preventive agent by modulating lipid metabolism in target tissues thus conferring protection against the attack of insults of different type.     

Effects of conjugated linoleic acid isomers on monocyte, macrophage and foam cell phenotype in atherosclerosis

Conjugated linoleic acid (CLA) is a generic term denoting a group of naturally occurring isomers of linoleic acid (18:2, n6) that differ in the position or geometry (i.e. cis or trans) of their double bonds. The predominant isomers in ruminant fats are cis-9,trans-11 CLA (c9,t11-CLA), and trans-10,cis-12 CLA (t10,c12-CLA). The biological activities of CLA have received considerable attention because of its protective effects in cancer, immune function, obesity and atherosclerosis. Importantly, dietary administration of a blend of the two most abundant isomers of CLA, has been shown to inhibit the progression and induce the regression of pre-established atherosclerosis in the ApoE?/? murine model. Studies investigating the mechanisms involved in CLA induced protective effects are continually emerging with results from both in vitro and in vivo models yielding confounding and often inconsistent results depending on both the isomer of CLA and the species under investigation. The purpose of this review is to comprehensively discuss the effects of CLA on monocyte/macrophage function in atherosclerosis. This review also discusses the possible mechanisms through which CLA mediates its atheroprotective effects with a particular emphasis on the migratory capacity of the monocyte and the inflammatory and cholesterol homeostasis of the macrophage.     

Isomer-specific effects of conjugated linoleic acid on mineralized bone nodule formation from human osteoblast-like cells

Mixed isomers of conjugated linoleic acid (CLA) have been shown to have variable effects on bone formation and resorption in animals. The variable effects of CLA on bone physiology may be due to the different isomers present in common commercial preparations of CLA, and the effects of the predominant individual isomers (9cis,11trans and 10trans,12cis CLA) are not clear. The objective of this study was to determine the effects of individual and mixed isomers of CLA on mineralized bone nodule formation and alkaline phosphatase (ALP) activity in vitro using long-term cultures of SaOS-2 cells. Mineralized bone nodules were stained using the von Kossa method, and ALP activity in cell lysates was measured as a marker of early osteoblast differentiation. The 9cis,11trans isomer increased the number (~4- to 11-fold) and size (~2- to 5-fold) of mineralized bone nodules from 25 to 100 microM, but the 10trans,12cis isomer did not. The increase in mineralized bone nodule formation by 9cis,11trans CLA was accompanied by a variable increase in ALP activity. These results show that the 9cis,11trans isomer of CLA increases the formation of mineralized bone nodules using bone cells of human origin, and provide evidence for isomer-specific effects of CLA on bone health.     

Differential effects of conjugated linoleic acid isomers on macrophage glycerophospholipid metabolism

Conjugated linoleic acids (CLA) are dietary fatty acids. Whereas cis-9,trans-11-(c9,t11)-CLA can be found in meat and dairy products, trans-9,trans-11-(t9,t11)-CLA is a constituent of vegetable oils. Previous studies showed that these two isomers activate different nuclear receptors and, thus, expression of genes related to lipid metabolism. Here we show that these CLA isomers are differentially elongated and desaturated in primary monocyte-derived macrophages isolated from healthy volunteers by using gas chromatography-mass spectrometry (GC-MS). We further demonstrate that c9,t11-CLA incorporates in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) species and activates de novo glycerophospholipid synthesis by quantitative electrospray ionization-tandem mass spectrometry (ESI-MS/MS). c9,t11-CLA leads to strong shifts of the species profiles to PC 18:2/18:2 and PE 18:2/18:2, which are due to de novo synthesis and fatty acid remodeling. In contrast, t9,t11-CLA is preferentially bound to neutral lipids, including triglycerides and cholesterol esters. Taken together our results show that c9,t11-CLA and t9,t11-CLA have differential effects on PC and PE metabolism. Moreover, these data demonstrate that the structure of fatty acids not only determines their incorporation into lipid classes but also modulates the kinetics of lipid metabolism, particularly PC synthesis.     

Dietary trans-vaccenic acid (trans11-18:1) increases concentration of cis9,transll-conjugated linoleic acid (rumenic acid) in tissues of lactating mice and suckling pups

Lactating mice were fed trans-vaccenic acid (trans 11-18:1, TVA) to assess desaturation of TVA to cis9,trans11-conjugated linoleic acid (9/11CLA). Diets contained 30 g x kg(-1) 18:2n-6 (LA) or 20 g LA plus 10 g 18:0 (SA), TVA, or a CLA mixture (MCLA). Compared with SA, feeding TVA increased 9/11CLA concentrations in blood plasma phospholipid, triglyceride, and free fatty acid fractions. However, concentrations of 9/11CLA in plasma fractions were greater when MCLA was fed compared with SA or TVA. No 9/11CLA was detected in liver of mice fed SA, and it was only 1 mg x g(-1) of total fatty acids in the carcass. In contrast, 9/11CLA content of liver (5 mg x g(-1)) and carcass (6 mg x g(-1)) of mice fed TVA was similar to liver (5 mg x g(-1)) and carcass (7 mg x g(-1)) of mice fed MCLA. Mammary tissue of SA-fed mice had no detectable 9/11 CLA, compared with 5 or 14 mg x g(-1) for TVA or MCLA-fed mice. Stearoyl-CoA desaturase activity in mammary tissue from TVA-fed dams was 14% greater compared with SA. Activity of this enzyme in liver tissue was similar among treatments. In pups nursing TVA-fed dams, 9/1 ICLA accounted for 3 mg x g(-1) in liver but no 9/11CLA was detected in the carcass. In pups nursing MCLA-fed dams, however, 9/11CLA accounted for 8 and 6 mg x g(-1) in liver and carcass. Results indicated TVA desaturation enhanced 9/11CLA in tissues and milk fat.     

Isomer-specific anti-obese and hypolipidemic properties of conjugated linoleic acid in obese OLETF rats

Conjugated linoleic acid (CLA), a mixture of positional and geometric isomers of linoleic acid, has attracted considerable attention because of its potentially beneficial biologic effects both in vitro and in vivo. Our results clearly show the specific action of the 10trans,12cis-CLA isomer against hyperlipidemia and obesity in obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats. After 2 weeks of feeding with 10t,12c-CLA, but not 9cis,11trans-CLA, abdominal adipose tissue weight and serum and hepatic lipid levels in OLETF rats were lower than those in linoleic acid-fed rats. These effects were attributable to suppressed fatty acid synthesis and enhanced fatty acid beta oxidation in the liver on a 10t,12c-CLA diet. Additionally, we showed that mRNA expression of fatty acid synthase, carnitine palmitoyltransferase, leptin, and sterol regulatory element binding protein-1 was also regulated by 10t,12c-CLA. We suppose that 10t,12c-CLA reveals hypolipidemic and anti-obese activity through the alteration of mRNA expressions in the liver and white adipose tissue.     

The 10trans,12cis isomer of conjugated linoleic acid suppresses the development of hypertension in Otsuka Long-Evans Tokushima fatty rats

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid found in beef, lamb, and dairy products. CLA has attracted considerable attention over the past several decades because of its potentially beneficial biological effects, including protective effects against several cancers, atherosclerosis, and obesity. Here we provide the first evidence that the 10trans,12cis-CLA isomer is able to suppress increases in blood pressure during the onset of obesity in OLETF rats. After 3 weeks of feeding with 10t,12c-CLA, systolic blood pressure was significantly lowered compared with rats fed linoleic acid or 9c,11t-CLA. Abdominal adipose tissue weight was also significantly lowered in rats fed 10t,12c-CLA, but not in those which were fed 9c,11t-CLA. In addition, we found that the relative mRNA expressions of angiotensinogen and leptin were suppressed by 10t,12c-CLA in adipose tissue. We speculate that the antihypertensive effect of 10t,12c-CLA can be attributed to the lowered secretion of hypertensive adipocytokines from abdominal adipose tissues.     

Effects of weaning and finishing feeding treatment on fatty acids, especially cis and trans C18:1 isomers, in the Longissimus thoracis muscle of Galician Blond calves

Seven- to 10-month-old calves are the typical production of Galician Blond (GB), the most important bovine local beef breed in Spain. As meat lipid repercussions on human health depend on their fatty acid (FA) profile, this study aimed at analysing the individual FA at weaning and at the end of the feeding finishing period, especially trans and cis 18:1 isomers in total lipids of the Longissimus thoracis muscle in GB male calves. Distribution of main FA in veal lipids was characterized by gas-liquid chromatography (GLC) analysis on a high polar glass capillary column. Total trans and cis 18:1 isomers were purified, from total FA (TFA) methyl esters, by preparative reversed-phase high-performance liquid chromatography, to allow subsequent specific analysis of their different isomers by GLC. Calves stayed with their mothers at pasture for 2 or 5 months in intensive or semi-extensive systems, followed by an indoor feeding period. The weaned (W) group was finished on concentrate and hay, whereas the non-weaned (NW) group was finished on concentrate and hay and it continued suckling until slaughter. The studied effects did not present interactions. The duration of the indoor finishing period hardly had a significant influence on the parameters analysed. Compared to W calves, NW calves had higher proportions (% TFA) of 18:3n-3 (+38%, P < 0.0001), 20:5n-3 (+22%, P = 0.005), 22:5n-3 (+13%, P = 0.042), cis monounsaturated FA (MUFA; +8%, P = 0.032), total MUFA (+8%, P = 0.013), n-3 polyunsaturated FA (PUFA; +25%, P = 0.0001) and conjugated linoleic acid (CLA; +48%, P < 0.0001) to the detriment of 18:0 (-10%, P = 0.002), 18:2n-6 (-25%, P = 0.004) and n-6 PUFA (-20%, P = 0.011). With regard to cis and trans 18:1 isomers, NW calves had higher proportions (% total cis or trans 18:1) of Δ11trans and Δ16trans (+25% and +22%, respectively, P < 0.01) and Δ13 + 14trans (+13%, P < 0.05) and lower proportions of Δ6 to 8 and Δ10trans (-28% and 58%, respectively, P < 0.001). NW calves' meat might be more suitable for human health than W calves' meat due to the increase of anti-atherogenous FA such as n-3 PUFA, CLA and 18:1 Δ11trans.     

The effect of conjugated linoleic acid on the viability and metabolism of human osteoblast-like cells

Studies in experimental animals and murine osteoblast cells in culture have produced conflicting findings on the effect of conjugated linoleic acid (CLA) on bone formation. The present study investigated the influence of CLA on viability and metabolism of two human osteoblast-like cell lines (SaOS2 and MG63). Both cell lines were exposed to increasing concentrations (0-50 microM) of CLA either as pure cis (c) 9: trans (t) 11 and t10:c12 CLA isomers or a blend of isomers, or linoleic acid (C18:2). Cell cytotoxicity and degree of DNA fragmentation were unaffected by any fatty acid treatment. PGE2 biosynthesis by both cell lines was variably reduced by CLA isomer blend and t10:c12 CLA, but not c9:t11 CLA. Alkaline phosphatase activity was variably increased by all CLA treatments. These results suggest a lack of cytotoxic effect of CLA on human osteoblast-like cells and tentatively suggest a possible beneficial effect on bone formation in humans.     

Complete stereospecific determination of conjugated linoleic acids in triacylglycerol of milk-fat

We analyzed two kinds of dairy fat differing in their contents of cis9, trans11-conjugated linoleic acid (cis9,trans 11-CLA or rumenic acid), and determined the positional distribution of this CLA-isomer within the three sn- positions of the triacylglycerol. In the high rumenic acid fat (HR), the CLA-isomers amounted to 2.1% of total fatty acids, and 0.8% in the low rumenic acid fat (LR). Over 90% of the total CLA-isomers were in the form of rumenic acid, with an identical isomeric CLA distribution in both fats. The two fats differed mainly with regards to their contents in palmitic acid, alpha-linolenic acid, and isomers of trans-C 18:1. Conversely, our stereospecific determination indicates that the positional distribution of rumenic acid is preserved among both types of fat, and is more specific for the sn-3 position of the triacylglycerol (54 to 64% of the total rumenic acid). Such a positional distribution is believed to be nutritionally relevant.     

Fatty acid composition and conjugated linoleic acid content of different tissues in rats fed individual conjugated linoleic acid isomers given as triacylglycerols small star,filled

HEAT TREATMENT OF VEGETABLE OILS GAVE RISE TO FOUR MAIN CONJUGATED LINOLEIC ACID (CLA) ISOMERS : the 9c,11t, 9t,11t, 10t,12c and 10t,12t. The diet of male Wistar rats was supplemented with 150 mg/day either 9c,11t-, 9t,11t-, 10t,12c- or 10t,12t CLA isomers for 6 days and their effects on lipid composition were investigated in liver, heart, skeletal muscle Gastrocnemius, kidneys, brain and adipose tissue. The incorporation of all isomers was low (< 1.4%) and the level was as follows : adipose tissue > Gastrocnemius > liver, kidneys > brain. The main changes in the overall lipid composition were observed in skeletal muscle (Gastrocnemius) and in heart and were associated with feeding the 10t,12c and 10t,12t isomers. The diet enriched in 10t,12t CLA decreased the total long chain polyunsaturated fatty acid proportion in Gastrocnemius (from 18.4% to 14.4%) and increased that of 20:4 n-6 in heart (from 16.9 to 19.3%). The diet enriched in 10t,12c CLA decreased the monounsaturated fatty acid proportion in Gastrocnemius (from 32.0 to 26.1%) and produced an effect similar to the 10t,12t in heart. By contrast, the 9c,11t and 9t,11t isomers did not affect fatty acid composition in all tissues and organs. We concluded that ingestion of 10t,12c and 10t,12t CLA present in oils and in CLA mixtures could change muscle lipid composition.