Dietary conjugated nonadecadienoic acid prevents adult-onset obesity in nescient basic helix–loop–helix 2 knockout mice

Conjugated linoleic acid (CLA) has been extensively studied during the last two decades with regard to its effects on controlling body composition. As a cognate to CLA, conjugated nonadecadienoic acid (CNA) has been previously reported to reduce body fat more effectively than CLA. However, it is not known whether CNA supplementation can influence adult-onset obesity. Thus, the purpose of this study was to evaluate the effects of dietary CNA on the prevention of adult-onset inactivity-induced obesity using nescient basic helix–loop–helix 2 knockout (N2KO) mice. CNA supplementation at 0.1 w/w% level starting in the preobese state significantly prevented the reduction of voluntary movement and the increase in weight gain in N2KO mice during the experimental period compared to wild-type animals. In both wild-type and N2KO mice, respiratory exchange ratio was significantly reduced by CNA treatment during light and dark cycles, and dietary CNA significantly increased energy expenditure in N2KO mice. Selected gene expression profiles in white adipose tissue, muscle or liver showed a beneficial action of CNA on lipid metabolism and energy expenditure. These findings suggest that CNA could prevent adult-onset obesity by enhancing voluntary activity and energy expenditure in N2KO mice.     

Influence of Dietary Conjugated Linoleic Acid and Fat Source on Body Fat and Apoptosis in Mice*

Objective: To determine whether altered dietary essential fatty acid (linoleic and arachidonic acid) concentrations alter sensitivity to conjugated linoleic acid (CLA)‐induced body fat loss or DNA fragmentation. Research Methods and Procedures: Mice were fed diets containing soy oil (control), coconut oil [essential fatty acid deficient (EFAD)], or fish oil (FO) for 42 days, and then diets were supplemented with a mixture of CLA isomers (0.5% of the diet) for 14 days. Body fat index, fat pad and liver weights, DNA fragmentation in adipose tissue, and fatty acid profiles of adipose tissue were determined. Results: The EFAD diet decreased (p < 0.05) linoleic and arachidonic acid in mouse adipose tissue but did not affect body fat. Dietary CLA caused a reduction (p < 0.05) in body fat. Mice fed the EFAD diet and then supplemented with CLA exhibited a greater reduction (p < 0.001) in body fat (20.21% vs. 6.94% in EFAD and EFAD + CLA‐fed mice, respectively) compared with mice fed soy oil. Dietary FO decreased linoleic acid and increased arachidonic acid in mouse adipose tissue. Mice fed FO or CLA were leaner (p < 0.05) than control mice. FO + CLA‐fed mice did not differ in body fat compared with FO‐fed mice. Adipose tissue apoptosis was increased (p < 0.001) in CLA‐supplemented mice and was not affected by fat source. Discussion: Reductions in linoleic acid concentration made mice more sensitive to CLA‐induced body fat loss only when arachidonic acid concentrations were also reduced. Dietary essential fatty acids did not affect CLA‐induced DNA fragmentation.     

The effects of dietary conjugated nonadecadienoic acid on body composition in mice.

A 19-carbon conjugated diene, conjugated nonadecadienoic acid (CNA), inhibited heparin-releasable lipoprotein lipase and reduced lipid stores in 3T3-L1 adipocytes similarly to conjugated linoleic acid (CLA). When fed to growing mice (0.3% of diet) CNA reduced body fat by 81% whereas CLA reduced body fat by 25%. CLA and CNA differ in length by one carbon atom so they are unlikely to share a common metabolite to account for these observations.     

Dietary conjugated linoleic acid increases immunoglobulin productivity of Sprague-Dawley rat spleen lymphocytes

The dietary effects of conjugated linoleic acid (CLA) on Ig production of Sprague-Dawley rats were examined at various doses such as 0 (control), 0.05, 0.10, 0.25, and 0.50%. CLA increased IgG and IgM production of spleen lymphocytes in a dose-dependent manner, and these levels reached a plateau at 0.25%. IgA production was not detected in the control group, while it was detected in all CLA-fed groups and IgA productivity of spleen lymphocytes increased in a dose-dependent manner at the doses from 0.05 to 0.50%. Dietary CLA did not affect serum Ig levels. The major fatty acid composition of spleen lymphocytes was not affected by dietary CLA, which itself was hardly incorporated into the cells. In an in vitro assay, the effects of CLA and its oxidative derivatives, furan type fatty acids, on Ig productivity were also examined. As a result, 100 microM CLA suppressed Ig production of spleen lymphocytes and the degree was as follows IgA > IgG > IgM. Each CLA isomer and the furan type fatty acids also suppressed Ig production but the degree was weaker than the mixture of CLA isomers. In this result, dietary CLA increased Ig productivity of spleen lymphocytes in vivo.     

Effect of dietary conjugated linoleic acid (CLA) on lipid composition, metabolism and gene expression in Atlantic salmon (Salmo salar) tissues

Dietary conjugated linoleic acid (CLA) affects fat deposition and lipid metabolism in mammals, including livestock. To determine CLA effects in Atlantic salmon (Salmo salar), a major farmed fish species, fish were fed for 12 weeks on diets containing fish oil or fish oil with 2% and 4% CLA supplementation. Fatty acid composition of the tissues showed deposition of CLA with accumulation being 2 to 3 fold higher in muscle than in liver. CLA had no effect on feed conversion efficiency or growth of the fish but there was a decreased lipid content and increased protein content after 4% CLA feeding. Thus, the protein:lipid ratio in whole fish was increased in fish fed 4% CLA and triacylglycerol in liver was decreased. Liver beta-oxidation was increased whilst both red muscle beta-oxidation capacity and CPT1 activity was decreased by dietary CLA. Liver highly unsaturated fatty acid (HUFA) biosynthetic capacity was increased and the relative proportion of liver HUFA was marginally increased in salmon fed CLA. CLA had no effect on fatty acid Delta6 desaturase mRNA expression, but fatty acid elongase mRNA was increased in liver and intestine. In addition, the relative compositions of unsaturated and monounsaturated fatty acids changed after CLA feeding. CLA had no effect on PPARalpha or PPARgamma expression in liver or intestine, although PPARbeta2A expression was reduced in liver at 4% CLA feeding. CLA did not affect hepatic malic enzyme activity. Thus, overall, the effect of dietary CLA was to increase beta-oxidation in liver, to reduce levels of total body lipid and liver triacylglycerol, and to affect liver fatty acid composition, with increased elongase expression and HUFA biosynthetic capacity.     

Influence of dietary conjugated linoleic acid (CLA) on lipid and fatty acid composition in liver and flesh of Atlantic salmon (Salmo salar)

The aim of the present study was to determine the effects of conjugated linoleic acid (CLA) on lipid and fatty acid metabolism in Atlantic salmon. The overall objective being to test the hypotheses that CLA has beneficial effects in salmon including growth enhancement, improved flesh quality through decreased adiposity and lipid deposition thereby minimising detrimental effects of feeding high fat diets, and increased nutritional quality through increased levels of beneficial fatty acids including n-3 highly unsaturated fatty acids (HUFA) and CLA itself. Salmon smolts were fed diets containing two levels of fish oil (low, approximately 18% and high, approximately 34%) containing three levels of CLA (a 1:1 mixture of 9-cis,trans-11 and trans-10,cis-12. at 0, 1 and 2% of diet) for 3 months and the effects on growth performance, liver and muscle (flesh) lipid contents and class compositions, and fatty acid compositions determined. The diets were also specifically formulated to investigate whether the effects of CLA, if any, were more dependent upon absolute content of CLA in the diet (as percentage of total diet) or the relative level of CLA to other fatty acids. Dietary CLA in salmon smolts had no effect on growth parameters or biometric parameters. However, there was a clear trend of increased total lipid and triacylglycerol contents in both liver and flesh in fish fed CLA, particularly in fish fed the high oil diets. Finally, CLA was incorporated into tissue lipids, with levels in flesh being 2-fold higher than in liver, but importantly, incorporation in liver was at the expense of saturated and monounsaturated fatty acids whereas in flesh it was at the expense of n-3HUFA.     

trans-10,cis-12-Conjugated linoleic acid reduces leptin secretion from 3T3-L1 adipocytes

The trans10,cis12 (t10c12) isomer of conjugated linoleic acid (CLA) has been shown to inhibit heparin-releasable lipoprotein lipase activity, reduce lipid stores in cultured 3T3-L1 adipocytes, and, when fed to mice, reduce body fat gain. We now report that t10c12 CLA significantly reduced leptin secretion from cultured 3T3-L1 adipocytes, and reduced leptin mRNA levels within the cells. Similar effects were produced by conjugated nonadecadienoic acid (a 19-carbon CLA cognate that is more effective than CLA in reducing body fat gain in mice), the lipoxygenase inhibitor nordihydroguaiaretic acid (which is synergistic with CLA in reducing body fat gain in mice), and ciglitazone (TZD, a PPARgamma agonist). Feeding mice diet supplemented with 0.5% t10c12 CLA for 4 weeks significantly reduced body fat gain, serum leptin levels and adipocyte leptin mRNA expression, without affecting feed intake or body weight. These data provide new insights into apparent mechanistic similarities among t10c12 CLA, CNA, NDGA, and TZD.     

Dietary manipulations of body fat-reducing potential of conjugated linoleic acid in rats.

To study whether the body fat-reducing potential of conjugated linoleic acid (CLA) could be increased through dietary manipulations, the effects of the combination of CLA with different proteins, fats, and sesamin were examined in rats. Male rats were fed diets containing 1% CLA or linoleic acid (LA) in combination with different proteins (20% of casein or soybean protein), fats (7% perilla oil or soybean oil) and 0.2% sesamin (SES) for 3 or 4 weeks. When the dietary fat source was soybean oil, CLA, as compared with LA, significantly reduced weights of epididymal and perirenal adipose tissues, irrespective of the dietary protein sources. However, the highest reducing effect was shown when soybean protein was given as a protein source. SES stimulated the reduction of epididymal and perirenal adipose tissue weights in both protein diets. In contrast, CLA increased the weight of brown adipose tissue, and SES further increased it in combination with soybean oil but not with perilla oil. No effect of dietary manipulation was observed on serum leptin and TNF-alpha levels. Thus, the body fat-reducing potential of CLA can be increased by an appropriate combination with food factors that may stimulate fatty acid beta-oxidation.     

Isomer-specific effects of conjugated linoleic acid (CLA) on adiposity and lipid metabolism

Isomers of conjugated linoleic acid (CLA), unsaturated fatty acids found in ruminant meats and dairy products, have been shown to reduce adiposity and alter lipid metabolism in animal, human, and cell culture studies. In particular, dietary CLA decreases body fat and increases lean body mass in certain rodents, chickens, and pigs, depending on the isomer, dose, and duration of treatment. However, the effects of CLA on human adiposity are conflicting because these studies have used different mixtures and levels of CLA isomers and diverse subject populations. Potential antiobesity mechanisms of CLA include decreased preadipocyte proliferation and differentiation into mature adipocytes, decreased fatty acid and triglyceride synthesis, and increased energy expenditure, lipolysis, and fatty acid oxidation. This review will address the current research on CLA's effects on human and animal adiposity and lipid metabolism as well as potential mechanism(s) responsible for CLA's antiobesity properties.     

Dietary Conjugated Linoleic Acid Increases Immunoglobulin Productivity of Sprague-Dawley Rat Spleen Lymphocytes

The dietary effects of conjugated linoleic acid (CLA) on Ig production of Sprague-Dawley rats were examined at various doses such as 0 (control), 0.05, 0.10, 0.25, and 0.50%. CLA increased IgG and IgM production of spleen lymphocytes in a dose-dependent manner, and these levels reached a plateau at 0.25%. IgA production was not detected in the control group, while it was detected in all CLA-fed groups and IgA productivity of spleen lymphocytes increased in a dose-dependent manner at the doses from 0.05 to 0.50%. Dietary CLA did not affect serum Ig levels. The major fatty acid composition of spleen lymphocytes was not affected by dietary CLA, which itself was hardly incorporated into the cells. In an in vitro assay, the effects of CLA and its oxidative derivatives, furan type fatty acids, on Ig productivity were also examined. As a result, 100 μM CLA suppressed Ig production of spleen lymphocytes and the degree was as follows IgA>IgG>IgM. Each CLA isomer and the furan type fatty acids also suppressed Ig production but the degree was weaker than the mixture of CLA isomers. In this result, dietary CLA increased Ig productivity of spleen lymphocytes in vivo.     

Dietary conjugated linoleic acid alters long chain polyunsaturated fatty acid metabolism in brain and liver of neonatal pigs

Effects of dietary conjugated linoleic acid (CLA, 1% mixed isomers) on n-6 long-chain polyunsaturated fatty acid (LCPUFA) oxidation and biosynthesis were investigated in liver and brain tissues of neonatal piglets. Fatty acid β-oxidation was measured in tissue homogenates using [1-¹⁴C]linoleic acid (LA) and -arachidonic acid (ARA) substrates, while fatty acid desaturation and elongation were traced using [U-¹³C]LA and GC-MS. Dietary CLA had no effect on fatty acid β-oxidation, but significantly decreased n-6 LCPUFA biosynthesis by inhibition of LA elongation and desaturation. Differences were noted between our ¹³C tracer assessment of desaturation/elongation and simple precursor-product indices computed from fatty acid composition data, indicating that caution should be exercised when employing the later. The inhibitory effects of CLA on elongation/desaturation were more pronounced in pigs fed a low fat diet (3% fat) than a high fat diet (25% fat). Direct elongation of linoleic acid to C20:2n-6 via the alternate elongation pathway might play an important role in n-6 LCPUFA synthesis because more than 40% of the synthetic products of [U-¹³C]LA accumulated in [¹³C]20:2n-6. Overall, the data show that dietary CLA shifted the distribution of the synthetic products of [U-¹³C]LA between elongation and desaturation in liver and decreased the total synthetic products of [U-¹³C]LA in brain by inhibiting LA elongation to C20:2n-6. The impact of CLA on brain LCPUFA metabolism of the developing neonate merits consideration and further investigation.     

Biological activities of conjugated fatty acids: conjugated eicosadienoic (conj. 20:2delta(c11,t13/t12,c14)), eicosatrienoic (conj. 20:3delta(c8,t12,c14)), and heneicosadienoic (conj. 21:2delta(c12,t14/c13,t15)) acids and other metabolites of conjugated linoleic acid

The elongated form of conjugated linoleic acid (CLA), conjugated eicosadienoic acid (CEA, conj. 20:2delta(c11,t13/t12,c14)), was generated from CLA by liver microsomal fractions. Subsequent testing showed that dietary CEA significantly reduced body fat, and increased lean mass similar to CLA when compared to controls. CEA also decreased lipoprotein lipase activity and triacylglyceride, and increased glycerol release in 3T3-L1 adipocytes, correlated with the trans-12,cis-14 isomer, but CEA required a longer incubation period than cells treated with CLA. Based on the fact that CEA fed animals had CLA in tissue, we suggest that the effect of CEA is due to the CLA converted from CEA in the system. The delta-6 desaturated and elongated form of trans-10,cis-12 CLA (conjugated eicosatrienoic acid, CETA, conj. 20:3delta(c8,t12,c14)) inhibited LPL activity and increased glycerol release but was less active than trans-10,cis-12 CLA or CEA. The 21-carbon conjugated fatty acid, conjugated heneicosadienoic acid (CHDA, conj. 21:2delta(c12,t14/c13,t15)), was not active on LPL inhibition, triacylglyceride, or glycerol release in 3T3-L1 adipocytes. We also provide evidence that CLA was metabolized to conjugated dodecadienoic acid (conj. 12:2delta(c3,t5/t4,c6)). In addition, there were indications of the presence of conjugated tetradecadienoic acid (conj. 14:2delta(c5,t7/t6,c8)), suggesting that CLA can be metabolized through fatty acid beta-oxidation. This is the first work to report the presence of conjugated 12 and 14 carbon fatty acids, originated from CLA, and the biological activities of CEA, CETA and CHDA.     

Efficacy and safety of dietary supplements containing CLA for the treatment of obesity: evidence from animal and human studies

Dietary supplements containing conjugated linoleic acid (CLA) are widely promoted as weight loss agents available over the counter and via the Internet. In this review, we evaluate the efficacy and safety of CLA supplementation based on peer-reviewed published results from randomized, placebo-controlled, human intervention trials lasting more than 4 weeks. We also review findings from experimental studies in animals and studies performed in vitro. CLA appears to produce loss of fat mass and increase of lean tissue mass in rodents, but the results from 13 randomized, controlled, short-term (<6 months) trials in humans find little evidence to support that CLA reduces body weight or promotes repartitioning of body fat and fat-free mass in man. However, there is increasing evidence from mice and human studies that the CLA isomer trans-10, cis-12 may produce liver hypertrophy and insulin resistance via a redistribution of fat deposition that resembles lipodystrophy. CLA also decreases the fat content of both human and bovine milk. In conclusion, although CLA appears to attenuate increases in body weight and body fat in several animal models, CLA isomers sold as dietary supplements are not effective as weight loss agents in humans and may actually have adverse effects on human health.     

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.     

Evidence that the anti-obesity effect of conjugated linoleic acid is independent of effects on stearoyl-CoA desaturase1 expression and enzyme activity

The trans-10,cis-12 isomer of conjugated linoleic acid (CLA) reduces body fat gain in animals and inhibits stearoyl-CoA desaturase (SCD) activity in 3T3-L1 adipocytes. To test whether CLA's body fat reduction is mediated by SCD1, wild-type and SCD1-null mice were fed diet supplemented with 0.2% trans-10,cis-12 (t10c12) CLA for 4 weeks. The t10c12 CLA-supplemented diet significantly reduced body fat mass in both wild type and SCD1-null mice. Similarly, t10c12 CLA diet decreased blood triglyceride and free fatty acid levels regardless of SCD1 genotypes. Mice fed t10c12 CLA exhibited increased mRNA expression of fatty acid synthase and uncoupling protein 2 in both genotypes. Taken together, the effects of t10c12 CLA on reduction of body fat gain, blood parameters, and mRNA expression in both SCD1-null mice and wild-type mice were similar, indicating that the anti-obesity effect of t10c12 CLA may be independent of the effects of this CLA isomer on SCD1 gene expression and enzyme activity.     

Effects of long-term supplementation of dairy cow diets with rumen-protected conjugated linoleic acids (CLA) on performance, metabolic parameters and fatty acid profile in milk fat

The supplementation of conjugated linoleic acids (CLA) to the rations of dairy cows represents an opportunity to reduce the content of milk fat. Therefore, CLA have the potential beneficial effect of reducing energy requirements of the early lactating cow. The present study aimed at the examination of long-term and posttreatment effects of dietary CLA intake on performance, variables of energy metabolism-like plasma levels of non esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB), and fatty acid profile in milk fat. Forty-six pregnant German Holstein cows were assigned to one of three dietary treatments: (1) 100 g/ d of control fat supplement (CON), (2) 50 g/d of control fat supplement and 50 g/ d of CLA supplement (CLA-1) and (3) 100 g/d of CLA supplement (CLA-2). The lipid-encapsulated CLA supplement consisted of approximately 10% of trans-10, cis-12 CLA and cis-9, trans-11 CLA each. The experiment started 1 d after calving and continued for about 38 weeks, divided into a supplementation (26 weeks) and a depletion period (12 weeks). Over the first 7 weeks of treatment, 11 and 16% reductions in dry matter intake compared to control were observed for the cows fed CLA-1 and CLA-2 supplements respectively. Consequently, the calculated energy balance for these two CLA groups was lower compared to the control. Plasma levels of NEFA and BHB remained unaffected. Later in lactation the highest CLA supplementation resulted in a reduction of milk fat content of 0.7%. However, no reduction in milk fat yield, and accordingly no milk fat depression (MFD), could be shown. The trans-10, cis-12 CLA in milk fat increased with increasing dietary CLA supplementation in a dose-dependent manner. The proportion of C16 in milk fat was decreased by the highest CLA supplementation. With the exception of an increase in plasma glucose level in the CLA-2 group, no post-treatment effects were observed. Overall, under the conditions of the present study no improvement in the calculated energy balance by CLA supplementation could be shown for the entire evaluation period.     

Combination of conjugated linoleic acid with fish oil prevents age-associated bone marrow adiposity in C57Bl/6J mice

The inverse relationship between fat in bone marrow and bone mass in the skeleton of aging subjects is well known. However, there is no precise therapy for the treatment of bone marrow adiposity. We investigated the ability of conjugated linoleic acid (CLA) and fish oil (FO), alone or in combination, to modulate bone loss using 12 months old C57Bl/6J mice fed 10% corn oil diet as control or supplemented with 0.5% CLA or 5% FO or 0.5% CLA+5% FO for 6 months. We found, CLA-fed mice exhibited reduced body weight, body fat mass (BFM) and enhanced hind leg lean mass (HLLM) and bone mineral density (BMD) in different regions measured by dual energy x-ray absorptiometry (DXA); however, associated with fatty liver and increased insulin resistance; whereas, FO fed mice exhibited enhanced BMD, improved insulin sensitivity, with no changes in BFM and HLLM. Interestingly, CLA+FO fed mice exhibited reduced body weight, BFM, peroxisome proliferator-activated receptor gamma and cathepsin K expression in bone marrow with enhanced BMD and HLLM. Moreover, CLA+FO supplementation reduced liver hypertrophy and improved insulin sensitivity with remarkable attenuation of bone marrow adiposity, inflammation and oxidative stress in aging mice. Therefore, CLA with FO combination might be a novel dietary supplement to reduce fat mass and improve BMD.     

Effects of conjugated linoleic acid levels and feeding intervals on performance, carcass traits and fatty acid composition of finishing barrows

Two experiments were conducted to investigate the effects of dietary conjugated linoleic acid (CLA) on performance, carcass traits, fatty acid composition and subcutaneous adipose tissue cellularity in finishing barrows. In Experiment 1, 54 crossbred barrows were allotted to one of three treatments, with six pens per treatment and three barrows in each pen. The pigs were fed a diet containing 0, 2, or 4% CLA oil for 6 weeks. Daily gain (P < 0.01) and feed efficiency (P < 0.01) improved with dietary CLA. Loin muscle area (P = 0.01) and intramuscular fat (P = 0.01) increased while 10th rib fat (P = 0.03) and last rib fat (P = 0.02) thickness decreased with increasing dietary CLA. Total CLA isomers increased (P < 0.01) with increasing dietary CLA. Myristic, palmitic and stearic acid levels were increased while oleic, linoleic, linolenic and arachidonic acid decreased in loin muscle and subcutaneous adipose tissue. In Experiment 2, barrows (n = 54) were allotted to one of two treatments with nine pens per treatment and three pigs in each pen. Pigs were fed a diet supplemented with 4% CLA for 3 or 6 weeks before slaughter. Over the entire experimental period, daily gain and feed efficiency were higher (P < 0.01) when CLA was fed for a longer period. Loin muscle area (P < 0.01) and intramuscular fat (P < 0.01) increased while backfat thickness at the 10th (P = 0.03) and last rib (P = 0.04) decreased when CLA was fed for 6 vs. 3 weeks. The number of cells in subcutaneous adipose tissue was not affected while adipocyte volume decreased (P = 0.01) with longer feeding time on dietary CLA. The increased CLA content of pork from CLA fed pigs provides the pork industry with an opportunity to provide value-added, healthful meat products for human consumption with respect to CLA intake and potential improvements in human health.     

Conjugated linoleic acid reduces body fats and cytokine levels of mice

In order to discover the effect of CLA on the body fat size and serum cytokine levels, four groups of male mice were fed diets containing either 1% linoleic acid (LA) or conjugated linoleic acid (CLA) with or without 0.2% sesamin for 8 weeks. The weight gain and feed efficiency were significantly lower in the CLA groups. CLA significantly reduced relative weights (g/100 g body weight) of epididymal and perirenal adipose tissues, in particular the former. Concentrations of serum TNF-alpha and leptin were significantly reduced by dietary CLA. Sesamin did not show additional effects in all of these parameters. There was a positive correlation between cytokine production and body-fat reducing potential of CLA. These results indicated that mice appeared to be a hyperresponder to dietary CLA insofar as the reduction of body fat size is concerned.