The biologically active isomers of conjugated linoleic acid.

Department of Food Microbiology and Toxicology, Food Research Institute, University of Wisconsin-Madison, 53706, USA.
Progress in Lipid Research (Impact Factor: 12.96). 08/2001; 40(4):283-98. DOI: 10.1016/S0163-7827(01)00008-X
Source: PubMed

ABSTRACT Numerous physiological effects are attributed to conjugated linoleic acid (CLA). The purpose of this presentation is to consider these effects with respect to the cis-9,trans-11 and trans-10,cis-12 CLA isomers. We review previously published data and present new findings that relate to underlying biochemical mechanisms of action. Both isomers are natural products. The cis-9,trans-11 isomer is the principal dietary form of CLA, but the concentrations of this isomer and the trans-10,cis-12 isomer in dairy products or beef vary depending on the diet fed to cows or steers, respectively. The trans-10,cis-12 CLA isomer exerts specific effects on adipocytes, in particular reducing the uptake of lipid by inhibiting the activities of lipoprotein lipase and stearoyl-CoA desaturase. The trans-10,cis-12 CLA isomer also affects lipid metabolism in cultured Hep-G2 human liver cells, whereas both the cis-9,trans-11 and trans-10,cis-12 CLA isomers appear to be active in inhibiting carcinogenesis in animal models. We present new findings indicating that the cis-9,trans-11 CLA isomer enhances growth and probably feed efficiency in young rodents. Accordingly, the effects of CLA on body composition (induced by trans-10,cis-12 CLA) and growth/feed efficiency (induced by cis-9,trans-11 CLA) appear to be due to separate biochemical mechanisms. We also show that a 19-carbon CLA cognate (conjugated nonadecadienoic acid, CNA) inhibits lipoprotein lipase activity as effectively as CLA in cultured 3T3-L1 adipocytes. Presumably, CNA is metabolized differently than the 18-carbon CLA isomers, so this finding indicates direct activity of the administered compound as opposed to acting via a metabolite.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: TITOLO Effetto del sistema di allevamento delle capre sulla qualità della carne del capretto lattante KEY WORDS Conjugated Linoleic Acid, goat production system, pasture, suckling kid, meat quality PAROLE CHIAVE Acido Linoleico Coniugato (CLA), sistema di allevamento, pascolo, capretto lattante, qualità della carne Summary The effect of grazing on pasture or feeding with concentrates was eva-luated on the concentration of Conjugated Linoleic Acid (CLA) in goat milk and in meat obtained from suckling kids fed only on maternal milk. The study used twenty male Ionica kids born as singletons from mature goats. The kids were reared with their dams, suckling ad libitum only maternal milk throughout the whole experimental period. Two groups of 10 kids each were formed according to their mothers' feeding treatment. One group of kids was raised under dams reared by an intensive produc-tion system (Group I -Intensive), while the other group of kids was rai-sed under dams grazing on pasture (Group E – Extensive). The goats were milked once a week in order to assess milk chemical composition, fatty acid profile and CLA concentration. Kids were slaughtered when 45 days old. Meat quality was evaluated on samples of the Longissimus lumborum (Ll) and Quardriceps femoris (Qf) muscles. On the whole, suckling kids raised under grazing goats showed a higher concentration of total CLA in both raw (2.57 vs 2.25%) and cooked meat (1.85 vs 1.44%), although the differences were not significant. Riassunto Lo scopo del lavoro è stato quello di valutare l'influenza del sistema ali-mentare e di allevamento sulle caratteristiche qualitative del latte di ca-pra, con particolare riferimento al contenuto di acido linoleico coniugato (CLA), e su quelle delle carni del capretto lattante. La prova è stata con-dotta su 20 capretti maschi di razza Ionica, nati da parto singolo da ca-pre mature. I capretti sono stati allevati con le proprie madri e nutriti esclusivamente con latte materno assunto ad libitum per l'intera durata della prova. Sono stati costituiti due gruppi di 10 capretti in relazione al sistema alimentare e di allevamento delle madri: un gruppo "estensivo" (Gruppo E) in cui le capre sono state alimentate al pascolo su erbaio; un gruppo "intensivo" (Gruppo I) in cui le capre sono state stabulate ed ali-mentate con fieno e concentrato. Le capre sono state munte una volta a settimana al fine di analizzare la composizione chimica, acidica e in CLA del latte. I capretti sono stati macellati all'età di 45 giorni. Le ca-ratteristiche qualitative delle carni sono state valutate su campioni dei
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Present study examined the effects of conjugated linoleic acid (CLA) supplementation on glycogen resynthesis in exercised human skeletal muscle. Twelve male participants completed a cross-over trial with CLA (3.8 g/day for 8 week) or placebo supplements by separation of 8 weeks. CLA is a mixture of trans-10 cis-12 and cis-9 trans-11 isomers (50:50). On experiment day, all participants performed 60-min cycling exercise at 75% VO2 max, then consumed a carbohydrate meal immediately after exercise and recovered for 3 h. Biopsied muscle samples from vastus lateralis were obtained immediately (0 h) and 3 h following exercise. Simultaneously, blood and gaseous samples were collected for every 30 min during 3-h recovery. Results showed significantly increased muscle glycogen content with CLA after a single bout of exercise (P < 0.05). Muscle glucose transporter type 4 expression was significantly elevated immediately after exercise, and this elevation was continued until 3 h after exercise in CLA trial. However, P-Akt/Akt ratio was not significantly altered, while glucose tolerance was impaired with CLA. Gaseous exchange data showed no beneficial effect of CLA on fat oxidation, instead lower non-esterified fatty acid and glycerol levels were found at 0 h. Our findings conclude that CLA supplementation can enhance the glycogen resynthesis rate in exercised human skeletal muscle.
    Journal of Sports Sciences 11/2014; · 2.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: – Ten lactating Saanen goats and their suckling kids were randomly assigned to two isonitrogenous diets: control diet (C) or soybean oil diet (SO); the two diets differed only by the inclusion of soybean oil (100 g/d in SO diet). At one month of age kids were slaughtered and from each one three muscle samples were collected: longissimus dorsi (LD), caput longum triceps brachii (CLOTB) and semimembranosus (SM). Lipids of milk and meat samples were extracted and analysed for fatty acid (FA) composition. Results showed that milk fat from goats fed the SO diet was richer in vaccenic acid and rumenic acid that increased respectively more than 500% and 600% if compared to C diet. With SO diet, also the other trans isomers of octadecenoic acid increased, included trans-10 C 18:1 , while saturated and medium chain fatty acid levels decreased. The intramuscular lipid content of kids fed SO milk resulted lower than that of kids fed C milk (1.58 g/100 g sample vs 1.81 g/100 g sample). The FA composition of intramuscular lipids of kids fed SO milk showed higher trans C 18:1 and CLA isomers proportions (1.15 vs 0.2 and 0.81 vs 0.26 g/100 g extracted fat, respectively for vaccenic acid and rumenic acid), while lower levels of saturated FA, branched chain FA, oleic acid and n-3 unsaturated FA (UFA) as compared to that from kids fed C milk. The ratio between cis-9 monounsaturated FA and their tissue precursors in the Δ9 desaturation pathway was negatively affected by the SO milk, especially for the rumenic acid/vaccenic acid pair. The n-6/n-3 ratio in the intramuscular lipids of kids fed C milk resulted lower than that of kids fed SO milk (5.25 vs 6.19, respectively). RESUME – "Effet de l'inclusion d'huile de soja dans le régime de chèvres laitières sur la composition en acides gras de la viande de leurs agneaux allaitants". Cette étude rapporte l'utilisation de 10 chèvres de race Saanen avec leurs chevreaux pour un essai expérimental où elles furent distribuées au hasard selon deux régimes d'alimentation, ayant le même niveau d'azote : régime témoin (C) et régime expérimental avec inclusion d'huile de soja (SO, 100 g/d)). A l'âge dun mois les chevreaux ont été abattus et sur la carcasse de chacun d'eux on a prélevé trois échantillons des muscles longissimus dorsi (LD), caput longum triceps brachii (CloTB) et semimembranosus (SM). On a extrait les lipides du lait et de la viande et on en a déterminé la composition en acides gras (AG). Les résultats ont montré que les lipides du lait des chèvres soumises au régime SO étaient plus riches en acide vaccénique et en acide ruménique de plus de 500% et 600%, en comparaison avec les lipides du régime C. Dans le régime SO il y avait même augmentation des trans-isomères de l'acide octadécénoïque, y compris le trans-10 C18:1; au contraire les acides saturés et les acides gras à chaîne moyenne diminuaient. Les lipides contenus dans le gras intramusculaire des chevreaux allaités avec le lait SO étaient en plus faible quantité que les lipides des chevreaux alimentés avec le lait C (1,58 g/100 g vs 1,81 g/100 g). La composition en AG des lipides intramusculaires des chevreaux SO montrait une proportion plus élevée de trans C18:1 et de CLA isomères (1,15 vs 0,2 et 0,81 vs 0,26, respectivement pour l'acide vaccénique et l'acide ruménique), au contraire les chevreaux SO avaient un niveau plus faible en AG saturés, AG à chaîne ramifiée, acide oléique et n-3 insaturés AG (IAG) par rapport à la viande des chevreaux alimentés avec le régime C. Le rapport entre cis-9 mono insaturés AG et leurs précurseurs dans l'itinéraire de désaturation au niveau du tissu, était négativement influencé par le lait SO, surtout pour le rapport acide ruménique/acide vaccénique. Le rapport n-6/n-3 dans les lipides intramusculaires des chevreaux alimentés avec le lait C, était plus bas que celui des chevreaux SO (5,25 vs 6,19, respectivement).


Available from