Biochemical and Molecular Action of Nutrients Research Communication An Isomeric Mixture of Conjugated Linoleic Acids But Not Pure cis-9,trans-11-Octadecadienoic Acid Affects Body Weight Gain and Plasma Lipids in Hamsters1 (original) (raw)
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British Journal of Nutrition, 2010
The effectiveness of conjugated linoleic acid (CLA) as a weight-loss nutraceutical continues to be debatable, suggesting that there may be value in exploring the physiological effects of the lesser-known isomers. The effects of the minor isomer, trans-8, cis-10 (t8,c10)-CLA, in the form of an equimolar mixture with the cis-9, trans-11 (c9,t11) isomer, on body weight and body composition, circulating glucose and lipid concentrations, and liver weights were studied in sixty male Syrian golden hamsters. Animals were randomised to receive for 28 d a semi-purified, hypercholesterolaemic diet (5 % dietary fat and 0•25 % cholesterol) supplemented at the 2 % level with either the t8,c10 þ c9,t11-CLA mixture, c9,t11-CLA or trans-10, cis-12 (t10,c12)-CLA replacing lard and safflower-seed oil (control). Results show that compared with control, the t8,c10 þ c9,t11-CLA mixture and t10,c12-CLA-fed animals had lower (P, 0•0001) fat mass following supplementation. Animals consuming t10,c12-CLA also possessed higher lean mass compared with control and c9,t11-CLA groups (P, 0•001). However, the livers of these animals were larger (P, 0•0001) compared with those in the control and other CLA groups. Body weights of the hamsters did not differ across the experimental groups. CLA treatments had no effect on serum glucose or lipid profile, except for inducing higher (P,0•05) non-HDL-cholesterol concentration with t10,c12-CLA compared with the c9,t11 isomer. Overall, these results indicate that in male hamsters fed a hypercholesterolaemic diet, the t8,c10 þ c9,t11-CLA mixture does not have an impact on blood lipid profile, but is able to effectively reduce fat mass, without incurring an accompanying liver enlargement.
Journal of Physiology and Biochemistry, 2003
Conjugated linoleic acid (CLA) refers to a mixture of naturally occurring positional and geometric isomers of linoleic acid that exist in dairy products and meat. The aim of the present work was to study the effects ofc-9,t-11 andt-10,c-12 CLA isomers on body fat accumulation and serum lipids in hamsters fed an atherogenic diet. Hamsters were divided in four groups: one group was fed a chow diet (control) and the other three groups were given semi-purified atherogenic diets with 0.5% linoleic acid (LA),c-9,t-11 ort-10,c-12 CLA. Body weight and food intake were measured daily. After 6 weeks, adipose tissues from different anatomical locations and liver were dissected and weighed. Serum glucose, total cholesterol, HDL-c, LDL-c and triacylglycerol levels, as well as total and free cholesterol, triacylglycerol and phospholipid content in liver were determined by enzymatic methods. No differences in either energy intake or final body weight were found. The addition oft-10,c-12 CLA reduced fat accumulation and led to lower serum cholesterol, as compared with LA group. Nevertheless the level remained higher than in the control animals. The reduction in serum cholesterol was limited to LDL-c. This isomer also reduced triacylglycerol content in liver but did not modify serum triacylglycerol level. In summary, the present study demonstrates thatt-10,c-12 CLA is the biologically active agent when anti-obesity and hypocholesterolaemic properties of CLA are considered. In contrast, the isomerc-9,t-11 has no effect on lipid metabolism in hamsters. El término ácido linoleico conjugado (ALC) se utiliza para designar una serie de isómeros del ácido linoleico, presentes en los lácteos y la carne, que presentan los dobles enlaces en posición conjugada. El objetivo del presente trabajo consistió en estudiar el efecto de los isómerosc-9,t-11 yt-10,c-12 del ALC sobre la acumulación de grasa corporal y los lípidos séricos, en hámsters alimentados con una dieta aterogénica. Los hámsters se distribuyeron en cuatro grupos: un grupo recibió pienso de laboratorio (control) y los otros tres grupos, dietas aterogénicas con 0,5% de ácido linoleico, ALCc-9,t-11 ó ALCt-10,c-12. Se midió diariamente la ingesta de alimento y el peso corporal. Tras 6 semanas, se diseccionaron y pesaron los tejidos adiposos de diferentes localizaciones anatómicas y el hígado. Se midieron las concentraciones séricas de glucosa, colesterol total, c-HDL, c-LDL y triglicéridos, y el contenido hepático de colesterol total y libre, triglicéridos y fosfolípidos, por métodos enzimáticos. No se encontraron diferencias significativas ni en la ingesta de energía ni en el peso corporal final. El isómerot-10,c-12 redujo la acumulación de grasa y disminuyó el colesterol total sérico; no obstante, su nivel se mantuvo por encima del de los animales control. La reducción del colesterol sérico se produjo a expensas del c-LDL. Este isómero también disminuyó el contenido hepático de triglicéridos pero no modificó los triglicéridos séricos. El presente estudio demuestra que el isómerot-10,c-12 del ALC es el biológicamente activo como agente anti-obesidad e hipocolesterolemiante. Por el contrario, el isómeroc-9,t-11 no afectó al metabolismo lipídico en hámsters.
Journal of Physiology and Biochemistry, 2006
The aim of the present work was to determine whether t-10, c-12 conjugated linoleic acid (CLA) feeding was able to reduce body fat accumulation and improve the serum lipid profile in adult hamsters fed an atherogenic diet, in order to compare these effects with those observed in young growing hamsters. Young and adult hamsters were fed semi-purified atherogenic diets supplemented with 0.5% linoleic acid or 0.5% t-10, c-12 CLA for 6 weeks. Body weight and food intake were measured every two days. Adipose tissue from different anatomical locations, liver and gastrocnemious muscle were dissected and weighed. Cholesterol, triacylglycerols, non-esterified fatty acids and proteins were determined spectrophotometrically and water content by gravimetry. In young hamsters, no significant differences were found in food intake, final body weight and gastrocnemious muscle weight. White adipose tissue weights were reduced, liver weight was increased and cholesterol and triacylglycerols in both serum and liver were reduced. In adult hamsters, CLA feeding decreased food intake and adipose tissue weights. No changes were observed in other parameters. The present study demonstrates that age has an influence in hamster responsiveness to t-10, c-12 CLA because, although when this isomer is added to an atherogenic diet it reduces body fat accumulation in both young and adults hamsters, the lessening of the effects on serum lipids brought about by atherogenic feeding is only observed in young animals. Moreover, it is clear that liver is a target for CLA in young but not in adult hamsters. El objetivo del presente estudio fue determinar si el isómero t-10, c-12 del ácido linoleico conjugado (ALC) era capaz de reducir la acumulación de grasa corporal y de mejorar el perfil lipídico en hámsteres adultos alimentados con una dieta aterogénica, con el fin de compararlos con los observados en hámsteres jóvenes en crecimiento. Los animales se alimentaron con dietas aterogénicas suplementadas con 0,5% de ácido linoleico ó 0,5% de ALC t-10, c-12 durante 6 semanas. Se midió cada dos días la ingesta de alimento y el peso corporal. Se diseccionaron y pesaron tejidos adiposos de diferentes localizaciones anatómicas, el hígado y los dos músculos gastrocnemios. El colesterol, los triglicéridos, los ácidos grasos libres y las proteínas se valoraron espectrofotométricamente ricamente y el agua por gravimetría. En los animales jóvenes no se observaron diferencias significativas en la ingesta, el peso corporal final y el peso de los músculos gastrocnemios. Los pesos de los tejidos adiposos blancos se redujeron, el peso de hígado aumentó y el colesterol y los triglicéridos disminuyeron, tanto en suero como en higado. En hámsteres adultos, el ALC disminuyó la ingesta y los pesos de los tejidos adiposos, pero no se observaron cambios en los demás parámetros. El presente estudio demuestra que la edad influye en la respuesta del hámster al ALC t-10, c-12 porque, aunque al ser anadido a una dieta aterogénica reduce la grasa corporal tanto en animales jóvenes como adultos, la atenuación de los efectos de esta dieta sobre los lípidos séricos sólo se pone de manifiesto en los jóvenes. Además, sólo en estos últimos, el hígado es claramente una diana para el ALC.
European journal of …, 2007
j Abstract Background Conjugated linoleic acid (CLA) has received great attention in recent years because of its pleiotropic biological activities, but considerably fewer studies have been published addressing its role in serum lipids and atherosclerosis compared to other topics covered. Aims of the study The aim of the present study was to assess the effects of the trans-10,cis-12 isomer of CLA on cholesterolaemia and on several metabolic pathways involved in cholesterol metabolism in hamsters. Methods Animals were fed atherogenic diets supplemented with 0.5% linoleic acid, 0.5% trans-10,cis-12 CLA or 1.0% trans-10,cis-12 CLA, for 6 weeks. Serum lipoproteins were separated by FPLC. Cholesterol in serum and liver, as well as triacylglycerols and phospholipids in liver were assessed by spectrophotometry. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCoAR), acyl-coenzyme A:cholesterol acyltransferase (ACAT) and cholesteryl ester hydrolase (CEH) activities were measured by radiometry, and LDL receptors were determined by Western blot. Results trans-10,cis-12 CLA feeding did not modify food intake nor final body weight. Although serum total cholesterol remained unchanged, when cholesterol fractions were analyzed a significant decrease in VLDL-cholesterol was observed in CLA-fed animals, without changes in HDL-cholesterol or LDL-cholesterol. trans-10,cis-12 CLA decreased cholesterol ester content and increased free cholesterol in liver. The activity of HMGCoAR was not modified. In contrast, ACAT activity was reduced by both CLA doses and CEH was increased by the high CLA dose. LDL receptors were significantly reduced by trans-10,cis-12 feeding when expressed as arbitrary units per mg of protein, however, the total receptor mass remained unchanged. Conclusions These results suggest that, under the present experimental conditions, trans-10,cis-12 CLA feeding reduces cholesterol esterification in liver and decreases the minority serum VLDL-cholesterol fraction, but it does not show a hypocholesterolaemic effect. A dose-response effect was not observed. j
Journal of the Science of Food and Agriculture, 2000
Four groups of 12 albino rats (six males and six females), at 4 weeks of age, were fed for 60 days a semi-synthetic diet containing graded amounts of conjugated linoleic acid (CLA; 0.0, 0.5, 1.0 and 1.5%) to determine its effect on growth performance and serum lipoprotein pro®les and its incorporation into abdominal and muscle lipids. Rats fed CLA responded by signi®cantly improved body mass gains; however, this effect was observed only with the 1.0% CLA-supplemented diet. It was also true for feed conversion ef®ciency. The changes in serum total cholesterol (TC) and HDL cholesterol concentrations were insigni®cant and showed an opposite pattern. However, the resulting HDL cholesterol/TC ratio was signi®cantly (P 0.01) increased. At the same time, serum triacylglycerol (TAG) concentrations were signi®cantly (P 0.01) elevated, thus counteracting the potential antiatherogenicity of the improved HDL cholesterol/TC ratio. Feeding CLA to rats resulted in its substantial incorporation into both abdominal and muscle lipids. Generally, tissue lipids were enriched with CLA at the expense of long-chain polyunsaturated fatty acids, eg linoleate and arachidonate. This effect is likely to correspond with reduction of arachidonate-derived eicosanoid synthesis. These data together suggest that CLA has a potent effect on lipid transport and metabolism in rats. Also, they con®rm the potential of nutritional methods to provide CLA-enriched functional animal products, especially meat, for human consumption.
Digestibility of Nutrients with the Inclusion of Conjugated Linoleic Acid in the Diet of Dogs
Archives of Veterinary Science, 2007
The inclusion of the conjugated linoleic acid (CLA) in food for dogs has been displaying great potential, taking into account several benefits in regard to the use of this product. To determine the effect of CLA on the digestibility of the dry matter, nutrients and energy in dogs, two experiments were performed using dogs of Beagle type, in the age of seven and 15 months, respectively. The experimental diets were isonutritive, just differing by the inclusion of CLA, watching for the addition to the control-diet, of an amount of lipids in the form of chicken fat equivalent to the amount of CLA added (0.3%), so that the diets were isoenergetic. The coefficients of apparent digestibility of the dry matter, crude protein, ethereal extract and nitrogen-free extract were not affected by the inclusion of conjugated linoleic acid, showing that the addition of the product did not interfere with the process of digestion of nutrients. In both digestibility experiments, higher values of metabolizable energy were observed for the diets with inclusion of CLA (P < 0.01) when compared with the control-diet. beagle; CLA; metabolizable energy. A inclusão do ácido linoléico conjugado (CLA) em rações para cães tem apresentado grande potencial, tendo em vista os vários benefícios relacionados à utilização deste produto. Para determinar o efeito do CLA sobre a digestibilidade da matéria seca, nutrientes e energia em cães foram realizados dois ensaios utilizando cães da raça Beagle, com sete e 15 meses de idade. As dietas experimentais eram isonutritivas, diferindo apenas quanto à inclusão de CLA, tomando-se o cuidado de acrescentar à dieta controle uma quantidade de lipídeos na forma de gordura de frango equivalente à quantidade de CLA adicionada (0,3%), para que as dietas fossem isoenergéticas. Os coeficientes de digestibilidade aparente da matéria seca, proteína bruta, extrato etéreo e extrativos não nitrogenados não foram afetados pela inclusão de ácido linoléico conjugado, mostrando que a adição do produto não interferiu no processo de digestão dos nutrientes. Em ambos os ensaios de digestibilidade, observaram-se valores de energia metabolizável superiores para as dietas com inclusão de CLA (P<0,01) quando comparada com a dieta controle. beagle; CLA; energia metabolizável.
European Journal of Lipid Science and Technology, 2019
This study aims to investigate the effect of conjugated linoleic acid (CLA) on nutritional parameters and triacylglycerol (TAG) regulation in male Wistar rats fed linoleic acid (LA)-deprived (ÀLA) diets compared to LAenriched (þLA) diets. In both þLA and ÀLA groups, CLA are incorporated into the tissues, showing higher levels in the adipose tissue. However, different metabolic and nutritional effects are observed depending on the LA status. CLA markedly reduces fat depots in the ÀLA group, associated with an increased lipoprotein lipase (LPL) and lipogenic enzyme activities as compensatory mechanisms. Moreover, CLA restores the hepatic TAG levels in ÀLA animals, associated with a normalized triacylglycerol-secretion rate (TAG-SR), an increased lipogenic enzyme activity and higher mRNA levels of fatty acid synthase. Serum TAG levels are not affected by CLA in the þLA group. However, in the ÀLA group, CLA decreases the TAG levels associated with a reduced TAG-SR and a higher adipose tissue LPL activity. Thus, the CLA effects on the nutritional parameters and TAG metabolism differs depending on the LA status. CLA causes certain beneficial biological and nutritional effects in LA-deprived but not in LA-enriched animals. Practical Applications: The approach by the authors involve growing animals in healthy physiological conditions fed with diets containing recommended levels of dietary fats, moderate amounts of commercial CLA mixture obtained from industrial synthesis (equimolecular amounts of 9c,11t-and 10t,12c-isomers), and unbalanced LA levels. These variables constitute a situation observed in the human population. The present study might contribute to understanding the role of CLA on nutritional parameters and TAG metabolism depending on the nutritional milieu.