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Journal ArticleDOI

Conjugated linoleic acid is synthesized endogenously in lactating dairy cows by Delta(9)-desaturase.

01 Sep 2000-Journal of Nutrition (American Society for Nutrition)-Vol. 130, Iss: 9, pp 2285-2291
TL;DR: Results demonstrate that endogenous synthesis of CLA from trans-11 18:1 represented the primary source of CLA in milk fat of lactating cows.
Abstract: Conjugated linoleic acid (CLA) is a naturally occurring anticarcinogen found in milk fat and body fat of ruminants. Although CLA is an intermediate in ruminal biohydrogenation of linoleic acid, we hypothesized that its primary source was from endogenous synthesis. This would involve Delta(9)-desaturase and synthesis from trans-11 18:1, another intermediate in ruminal biohydrogenation. Our first experiment supplied lactating cows (n = 3) with trans-11 18:1 by abomasal infusion and examined the potential for endogenous synthesis by measuring changes in milk fat CLA. By d 3, infusion of trans-11 18:1 resulted in a 31% increase in concentration of cis-9, trans-11 CLA in milk fat, demonstrating that an active pathway for endogenous synthesis of CLA exists. Our second experiment examined the quantitative importance of endogenous synthesis of CLA in lactating cows (n = 3) by abomasally infusing a putative stimulator (retinol palmitate) or an inhibitor (sterculic oil) of Delta(9)-desaturase. Infusion of retinol palmitate had no influence on milk fatty acid desaturation, and yield of CLA in milk fat was not altered. However, sterculic oil infusion decreased the concentration of CLA in milk fat by 45%. Consistent with Delta(9)-desaturase inhibition, the sterculic oil treatment also altered the milk fat concentration of other Delta(9)-desaturase products as indicated by the two- to threefold increase in the ratios of 14:0 to 14:1(,) 16:0 to 16:1 and 18:0 to cis-18:1. Using changes in the ratio of 14:0 to 14:1 as an indication of the extent of Delta(9)-desaturase inhibition with the sterculic oil treatment, an estimated 64% of the CLA in milk fat was of endogenous origin. Overall, results demonstrate that endogenous synthesis of CLA from trans-11 18:1 represented the primary source of CLA in milk fat of lactating cows.
Citations
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Journal ArticleDOI
28 Nov 2003
TL;DR: A more complete identification of these naturally produced inhibitors of fat synthesis and delineation of cellular mechanisms may offer broader opportunities for application and understanding of the regulation of lipid metabolism.
Abstract: Certain diets cause a marked reduction in milk fat production in ruminants. Commonly referred to as milk fat depression (MFD), the mechanism involves an interrelationship between rumen microbial processes and tissue metabolism. Numerous theories to explain this interrelationship have been proposed and investigations offer little support for theories that are based on a limitation in the supply of lipogenic precursors. Rather, the basis involves alterations in rumen biohydrogenation of dietary polyunsaturated fatty acids and a specific inhibition of mammary synthesis of milk fat. The biohydrogenation theory proposes that under certain dietary conditions, typical pathways of rumen biohydrogenation are altered to produce unique fatty acid intermediates that inhibit milk fat synthesis. Trans-10, cis-12 conjugated linoleic acid (CLA) has been identified as one example that is correlated with the reduction in milk fat. Investigations with pure isomers have shown that trans-10, cis-12 CLA is a potent inhibitor of milk fat synthesis, and similar to diet-induced MFD, the mechanism involves a coordinated reduction in mRNA abundance for key enzymes involved in the biochemical pathways of fat synthesis. A more complete identification of these naturally produced inhibitors of fat synthesis and delineation of cellular mechanisms may offer broader opportunities for application and understanding of the regulation of lipid metabolism.

1,094 citations

Journal ArticleDOI
TL;DR: Improved gas-liquid and high performance liquid chromatography were used and data on the trans and cis isomers of fatty acid and of conjugated linoleic acids are given, and the analyses are described.

881 citations

Journal ArticleDOI
TL;DR: Health benefits, metabolism, and potential mechanisms of action of CLA are focused on and the implications regarding dietary CLA for human health are postulated.
Abstract: ▪ Abstract Conjugated linoleic acid (CLA) is a group of polyunsaturated fatty acids found in beef, lamb, and dairy products that exist as positional and stereo-isomers of octadecadienoate (18:2). Over the past two decades numerous health benefits have been attributed to CLA in experimental animal models including actions to reduce carcinogenesis, atherosclerosis, onset of diabetes, and body fat mass. The accumulation of CLA isomers and several elongated/desaturated and β-oxidation metabolites have been found in tissues of animals fed diets with CLA. Molecular mechanisms of action appear to include modulation of eicosanoid formation as well as regulation of the expression of genes coding for enzymes known to modulate macronutrient metabolism. This review focuses on health benefits, metabolism, and potential mechanisms of action of CLA and postulates the implications regarding dietary CLA for human health.

843 citations

Journal ArticleDOI
TL;DR: Strategies for increasing the content of beneficial omega-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA) and reducing saturated fatty acid (SFA) in beef are reviewed and opportunities exist to enhance thecontent of health promoting fatty acids in beef and beef products offering opportunities to add value and contribute to market differentiation.

790 citations


Cites background from "Conjugated linoleic acid is synthes..."

  • ...However, Griinari et al. (2000) and Palmquist (2001) showed that the primary source of CLA cis-9, trans-11 is endogenous synthesis from TVA formed during ruminal biohydrogenation and involving D9-desaturase (Khanal & Dhiman, 2004; Song & Kennelly, 2003)....

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Journal ArticleDOI
TL;DR: More studies in rodents and humans fed dairy products modified by changing ruminant diet are required before recommending a larger use of lipid sources and how to combine them with the different feeding systems used by dairy farmers.
Abstract: The potential to modify the milk fatty acid (FA) composition by changing the cow or goat diets is reviewed. Ruminal biohydrogenation (RBH), combined with mammary lipogenic and A-9 desaturation pathways, considerably modifies the profile of dietary FA and thus milk composition. The pasture has major effects by decreasing saturated FA and increasing FA considered as favorable for human health (c9-18:1, 18:3n-3 and c9t11-CLA), compared to winter diets, especially those based on maize silage and concentrates. Plant lipid supplements have effects similar to pasture, especially linseed, but they increase to a larger extent, simultaneously several trans isomers of 18:1 and, conjugated or non-conjugated 18:2, especially when added to maize silage or concentrate-rich diets. The goat responds better for milk 18:3n-3 and c9t11-CLA, and sometimes less for c9-18:1, and is less prone to the RBH trans-11 to trans-10 shift, which has been shown to be time dependent in the cow. The respective physiological roles of most milk trans FA have not been studied to date, and more studies in rodents and humans fed dairy products modified by changing ruminant diet are required before recommending a larger use of lipid sources and how to combine them with the different feeding systems used by dairy farmers.

748 citations


Cites background from "Conjugated linoleic acid is synthes..."

  • ...Furthermore, C10–C19 may be D-9desaturated by the SCD, resulting in particular in palmitoleoyl-CoA, the major part (70–95%) of bovine milk c9t11-CLA [51, 59, 64, 65] and t7c9-CLA [66] and mainly oleyl-CoA [67, 68]....

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References
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Book
01 Jan 2006
TL;DR: In this article, the authors present official methods of analysis of AOAC International, official methods for analysis of aOAC-related project, and a set of methods for the analysis of their work.
Abstract: Official methods of analysis of AOAC International , Official methods of analysis of AOAC International , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

8,888 citations

Journal ArticleDOI
TL;DR: An improved method for extracting the lipids from tissues consists of the use of hexane:isopropanol, followed by a wash of the extract with aqueous sodium sulfate to remove nonlipid contaminants.

2,400 citations

Journal ArticleDOI
TL;DR: In this article, an improved method for quantifying linoleic acid (CLA) in food was developed, which was used to produce a data base of more than 90 food items including meat, poultry, seafood, dairy products, plant oils, and infant and processed foods.

1,228 citations

Journal ArticleDOI
TL;DR: A simple procedure suitable for rapid transmethylation of triacylglycerols, other neutral lipids, and glycerophospholipids is described, which can occur within a few minutes with no hydrolysis.

985 citations

Journal ArticleDOI
TL;DR: The goal of this review is to provide an overview of the genetic regulation of the stearoyl-CoA desaturase in response to dietary polyunsaturated fatty acids and cholesterol.

758 citations