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Review Article

Mechanisms of Action of Conjugated Linoleic Acid: Evidence and Speculation

Michael W. Pariza^*,1, Yeonhwa Park^* and Mark E. Cook^*,

^* Food Research Institute, Department of Food Microbiology and Toxicology, University of Wisconsin-Madison, Madison, Wisconsin 53706; and
Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706

	Abstract

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
Conjugated linoleic acid (CLA) has been shown to inhibit carcinogenesis and atherosclerosis, enhance immunologic function while protecting against the catabolic effects of immune stimulation, affect body composition change (reducing body fat gain while enhancing lean body mass gain), and stimulate the growth of young rats. We discuss possible biochemical mechanisms that underlie these physiological effects. We emphasize the importance of considering the effects, both individually and combined, of the two CLA isomers (cis-9, trans-11 CLA and trans-10, cis-12 CLA) that have been shown to exhibit biological activity and which appear to exert their effects via different biochemical mechanisms.

	Introduction

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
The term conjugated linoleic acid refers to a class of positional and geometric conjugated dieonic isomers of linoleic acid (Fig. 1). We coined the acronym CLA when we reported that conjugated linoleic acid, isolated from grilled beef or produced by base-catalyzed isomerization of linoleic acid, was an effective inhibitor of benzo[a]pyrene-initiated mouse epidermal neoplasia (1). This was followed by our observation that feeding CLA (0.5%of diet) to rodents or chickens protected them from the catabolic effects of immune stimulation (2, 3). CLA enhanced feed efficiency in young rats (4) indicating that it may regulate energy metabolism and nutrient partitioning, a conclusion that has been verified (5). We also found that dietary CLA reduced blood lipids and the development of atherosclerosis in rabbits fed an atherogenic diet (6). These findings have been confirmed independently and expanded in different models by other investigators (7) (for an updated listing of the scientific literature on CLA since 1987, which expands weekly, see the internet address http://www.wisc.edu/fri/clarefs.htm).

View larger version (34K): [in this window] [in a new window]   Figure 1.   Structures of (top) trans-10,cis-12 CLA, (middle) cis-9,trans-11 CLA, and (bottom) linoleic acid. (From (58), reprinted with permission.)

	CLA Is Not a Single Substance

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
The term conjugated linoleic acid and its acronym CLA refer generally to mixtures of positional and geometric conjugated dieonic isomers of linoleic acid. Many CLA isomers are produced when linoleic acid is heated in the presence of base (8, 9). Numerous CLA isomers are also found in milkfat, cheese, and beef (10). However, the cis-9,trans-11 isomer is the principal dietary form of CLA (9-13).

The cis-9,trans-11 isomer of CLA is produced in the rumen of cattle and other ruminant animals during the microbial biohydrogenation of linoleic and linolenic acids (14). Thereafter cis-9,trans-11 CLA may be absorbed directly (4) or biohydrogenated to vaccenic acid (trans-11-octadecenoic acid). Vaccenic acid, after absorption, may then be converted by -9 desaturase within mammalian cells back to cis-9,trans-11 CLA (15-17).

In addition to vaccenic acid, trans-10-octadecenoic acid is also found in cow's milk (18). Verhulst et al. (19) isolated a microorganism that converts linoleic acid to trans-10,cis-12 CLA, so it is likely, by analogy to vaccenic acid, that trans-10-octadecenoic acid may form in the rumen via microbial metabolism of linoleic acid to trans-10,cis-12 CLA, which is then biohydrogenated at the cis-12 bond. Since mammals do not possess -12 desaturase, it follows that the trans-10,cis-12 CLA reported in ruminant tissues [and which apparently can be increased by dietary manipulation (Dhiman T, Griinari M, personal communication)] would originate from trans-10,cis-12 CLA that was absorbed from the gastrointestinal tract. However, Park and Pariza (20) presented evidence indicating that commercial horse sera can sometimes contain substantial levels of apparent trans-10,cis-12 CLA. Since the horse has a hindgut fermentation area (rather than a rumen) where long-chain fatty acid absorption is minimal, the finding of apparent trans-10,cis-12 CLA in a sample of horse sera indicates that the origin of CLA isomers in the blood may be more complex than currently thought.

Uchida (21) reported the apparent de novo synthesis of CLA isomers by Pediococcus homari (as opposed to the generation of CLA isomers by isomerizing linoleic or linolenic acids, as is the case with all other known CLA-producing microorganisms). The origins of other CLA isomers that have been reported to occur naturally in milkfat (10) are not known, but one may conjecture that these also result largely, if not completely, from bacterial metabolism in the rumen.

The many physiological effects of CLA in animal models reported to date have been produced by feeding mixtures of CLA isomers that contain mostly cis-9,trans-11 and trans-10,cis-12 CLA in approximately equal amounts, with other CLA isomers at considerably lower levels (10, 11). For example, CLA that we typically produce for experimental use consists of the cis-9,trans-11 (40.85–41.1%), trans-10,cis-12 (43.5–44.9%), and trans-9,trans-11/trans-10,trans-12 (4.6%–10%) isomers (5, 9, 11). One should be cautioned, however, that some commercial CLA preparations contain additional isomers with conjugated double bonds at the 8, 10, or 11, 13 positions (11). Obviously the presence of additional CLA isomers will complicate data interpretation.

	Physiological Effects of CLA Isomers

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
Reports are now indicating that the cis-9,trans-11 and trans-10,cis-12 isomers induce different effects. Park et al. (22) provided evidence indicating that the CLA-associated body composition changes in mice result from feeding the trans-10,cis-12 CLA isomer. Table I is taken from that report. CLA preparations were enriched for the cis-9,trans-11 CLA isomer, or the trans-10,cis-12 CLA isomer. Body composition changes, exhibited as reduced body fat, enhanced body water, enhanced body protein, and enhanced body ash, were associated with feeding the trans-10,cis-12 CLA isomer. Similar findings have been reported for hamsters (23).

Lee et al. (25) provided limited evidence indicating that the trans-10,cis-12 CLA isomer decreased the expression of hepatic stearoyl-CoA desaturase mRNA in mice, whereas enzymatically synthesized cis-9,trans-11 CLA was not active in this regard. In collaborative studies with Professor James Ntambi of the University of Wisconsin-Madison Department of Biochemistry, we are finding that highly purified trans-10,cis-12 CLA, but not cis-9,trans-11 CLA, decreases the expression of stearoyl-CoA desaturase in cultured 3T3-L1 adipocytes (unpublished data). This may relate to the report (17) that the trans-10,cis-12 CLA isomer depressed milk fat synthesis in cows.

Yotsumoto et al. (26) reported that the trans-10,cis-12 CLA isomer reduced apolipoprotein B secretion in cultured human hepatoma HepG2 cells, thereby confirming and expanding upon the findings of Lee (27) and Pariza and Lee (28) that a mixture of cis-9,trans-11 and trans-10,cis-12 CLA isomers reduced apolipoprotein B secretion in this cell line. Trans-10,cis-12 CLA reduced triacylglyceride secretion in HepG2 cells (24, 26) although the effect of this isomer on triacylglyceride synthesis in this cell line was less clear (compare findings in references 24 and 26). It is not yet known which CLA isomer(s) are involved in other reported effects on atherosclerosis in various animal models (6, 29-31).

DeVoney et al. (32) provided evidence indicating that the trans-10,cis-12 CLA isomer alters lymphocyte blastogenesis. Further research on the effects of this isomer on the immune system is in order. In this regard mixtures of CLA isomers (mostly cis-9,trans-11 and trans-10,cis-12) have been shown to enhance the immune system (2, 33-35), reduce the catabolic effects of immune stimulation (2, 3), and reduce the release of prostaglandin E2 and leukotriene B4 from antigen-challenged lung, trachea, and bladder in the guinea pig (36).

In summary, the reported effects of CLA on lipid metabolism and body composition, and at least some of the effects of CLA on the immune system, appear to be due to trans-10,cis-12 CLA. What, then, might the cis-9,trans-11 CLA isomer do?

Ip has obtained evidence indicating that the cis-9,trans-11 and trans-10,cis-12 CLA isomers may be equally effective in inhibiting carcinogenesis (Ip C, personal communication). We have obtained limited evidence indicating that cis-9,trans-11 CLA may be important in effecting the CLA-induced growth enhancement in young rodents (4) and further that trans-10,cis-12 CLA may interfere with the growth enhancement induced by the cis-9,trans-11 isomer. Belury and Vanden Heuvel (37) found that cis-9,trans-11 CLA is a potent activator and high-affinity ligand for peroxisome proliferator–activated receptor- (PPAR-), but a CLA isomer mixture containing both cis-9,trans-11 and trans-10,cis-12 CLA did not induce peroxisome proliferation in rat liver (38). Whether other CLA isomers also induce physiological effects is not yet known.

As a result of these findings, the apparent multifunctionality of CLA has become more intriguing and less perplexing. Different isomers appear to produce different effects. It is also virtually certain that more than one biochemical mechanism is involved in the various physiological effects of CLA. In fact, more than one biochemical mechanism may even be involved in the effects of individual CLA isomers, in particular the trans-10,cis-12 isomer.

	Multiple Biochemical Mechanisms

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
Our working hypothesis is that the numerous biological effects reported for CLA cannot be explained by a single biochemical mechanism. A major direct line of support for this conclusion is that the trans-10,cis-12 and cis-9,trans-11 isomers appear to produce different effects, and it is difficult to imagine a single mechanism that accounts for this observation. By extension, even those effects that are clearly attributed to a single isomer may not all be caused by the same biochemical mechanism. For example, we have obtained evidence indicating that trans-10,cis-12 CLA directly inhibits the activity of stearoyl-CoA desaturase. Again, it is difficult to imagine how this finding alone could explain the range of physiological effects of this CLA isomer.

One might speculate that the inhibition of carcinogenesis by CLA could result from the combined effects of a number of CLA activities, possibly including direct effects of one or more CLA isomers/metabolites on cell differentiation (39), effects of CLA on vitamin A metabolism that would also influence cell differentiation (40), and effects of one or more CLA isomers on prostaglandin metabolism (41, 42), which may also influence cancer development at some sites (43). Similarly, the effects of CLA on lipid metabolism may be mediated by effects of the trans-10,cis-12 isomer and/or its metabolites on both the regulation and biochemical activities of key adipocyte and skeletal muscle enzymes (5, 22, 25) as well as effects on adipocyte differentiation (37, 44, 45).

Accordingly, we should now consider how CLA might effect the complex signaling required for such putative multiple biochemical mechanisms.

	CLA and Eicosanoids

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
Given the structural similarities between the CLA isomers and linoleic acid, it seems likely that at least some of the activities of CLA may be mediated via modification of intracellular signaling by eicosanoids and other lipid mediators. In this regard CLA could effect the synthesis and/or action of these mediators. Alternatively, the CLA isomers could be desaturated and elongated, then further metabolized to produce various CLA-derived eicosanoids and other novel mediators that would exhibit biological activities in their own right. Evidence exists for both of these propositions. (The term eicosanoid refers to metabolites of arachidonic acid, and since 20 carbon derivatives of CLA are also isomers of arachidonic acid, we believe that the term CLA-derived eicosanoid is justified. The possibility that CLA metabolites of different chain lengths may also be biologically active should be considered as well).

Research from a number of laboratories indicates that CLA effects the synthesis of prostaglandins, in particular PGE₂ (46). Sebedio et al. (47) have provided evidence indicating the both cis-9,trans-11 and trans-10,cis-12 CLA are elongated and desaturated in manners analogous to that of linoleic acid, hence providing precursors for putative CLA-derived eicosanoids. Pariza et al. (48) provided evidence indicating that conjugated eicosadienoic acid, CEA, produced by heating eicosadienoic acid in the presence of base, produces changes in body composition in mice that are similar to that of CLA. Hence it seems likely that the mechanisms of action of the CLA isomers involve, at least in part, effects both on eicosanoid signaling, as well as possibly unique signaling by CLA-derived eicosanoids. Altered eicosanoid signaling, and CLA-derived eicosanoid signaling, could in turn effect a range of biological activities including lipid metabolism and cytokine synthesis/function (49).

It should also be noted that trans-10,cis-12 CLA appears to be metabolized more rapidly than cis-9,trans-11 CLA, particularly in skeletal muscle (45). Whether this is due to enhanced elongation/desaturation, enhanced ß-oxidation, or both, is not yet known. However, given obvious structural differences (Fig. 1), one might expect CLA-derived eicosanoids that originate from trans-10,cis-12 CLA to be functionally distinct from those that might arise from cis-9,trans-11 CLA.

	CLA and Cytokines

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 
Cytokines are hormone-like mediators of immunity and inflammation that are produced by macrophages and other immune cells when they are stimulated. Tumor necrosis factor- (TNF-), along with interleukin-1 (IL-1), induce a number of effects in immune cells including the inflammatory response (50). However, these cytokines also produce biochemical changes in other cells, for example the induction of catabolism in skeletal muscle (51) and changes in cell surface proteins (52, 53).

Interestingly, virtually every cell in the body has receptors for TNF-, and many types of cells (e.g., nerve cells, adipocytes) can also produce this cytokine (51). It is also noteworthy that both the synthesis and action of TNF- and IL-1 are regulated by eicosanoids, in particular prostaglandin E₂ (PGE₂) (50).

TNF- appears to be a key mediator in many chronic pathologies including cachexia (54), atherosclerosis (55), carcinogenesis (56, 57), and (paradoxically) obesity (51). The association of TNF- with so many biological and physiological processes has led Hotamisligil and Spiegelman (51) to conclude that this cytokine produces a "... bewildering array of biochemical changes in a wide variety of cells ... attributable to its capacity for using multiple signaling pathways through its cell surface receptors." Hence TNF-, like CLA, is multifunctional.

The data of Figure 2 (from Ref. 42) are germane to this discussion. Mice were fed control diet or diet supplemented with 0.5% CLA for 32 days, then injected with TNF- as indicated. The CLA-fed mice experienced less weight loss indicating that they were partially protected against the cachexia that was induced by the cytokine. These results provide evidence indicating that CLA may modulate a cellular response to TNF-, possibly through the regulation of eicosanoid/CLA-derived eicosanoid production and/or type.

View larger version (16K): [in this window] [in a new window]   Figure 2.   Dietary CLA protects against cachexia induced by TNF-. Forty 4-week-old male ICR mice (Harlan Sprague-Dawley, Madison, WI) were housed, two per cage, in a windowless room on a 12:12-hr light:dark cycle, in strict accord with guidelines established by the Research Animal Resources Center of the University of Wisconsin-Madison. The animals were divided into two groups of equal size. One group was fed a semipurified diet (TD94060, Harlan Teklad, Madison, WI). The other group was fed the same diet supplemented with 0.5% CLA, for 32 days (fresh diet was provided each day). At Day 28, half of the animals in each group were injected (i.p.) with recombinant murine TNF- (200 µg/kg body weight) (R&D Systems, Minneapolis, MN) in phosphate-buffered saline (PBS); the remaining mice were injected with PBS alone. Points represent the differences between TNF-–treated mice and their respective PBS control counterpart for 42 hr postinjection. The r2 values are 0.9742 for control () and 0.8320 for CLA (). Using regression analysis with indicator variables, tests were conducted for the null hypotheses that each slope equaled 0 and for the null hypothesis that the two slopes were the same. The slopes are significantly different from each other and from 0 (P < 0.05). (From (42).)

Our expectation is that evidence for this hypothesis will continue to mount and will be a major theme when this review is updated three years hence.

	Footnotes

 
This research was supported in part by gift funds administered through the University of Wisconsin-Madison Food Research Institute. The authors are inventors of CLA use patents that are assigned to the Wisconsin Alumni Research Foundation (WARF).

¹ To whom requests for reprints should be addressed at Food Research Institute, Department of Food Microbiology and Toxicology, University of Wisconsin-Madison, 1925 Willow Drive, Madison, WI 53706. E-mail: mwpariza{at}facstaff.wisc.edu

	References

Top Abstract Introduction CLA Is Not a... Physiological Effects of CLA... Multiple Biochemical Mechanisms CLA and Eicosanoids CLA and Cytokines References

 

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				K. A. Cummins, S. G. Solaiman, and W. G. Bergen The effect of dietary copper supplementation on fatty acid profile and oxidative stability of adipose depots in Boer x Spanish goats J Anim Sci, February 1, 2008; 86(2): 390 - 396. [Abstract] [Full Text] [PDF]

				E. Rosberg-Cody, M. C. Johnson, G. F. Fitzgerald, P. R. Ross, and C. Stanton Heterologous expression of linoleic acid isomerase from Propionibacterium acnes and anti-proliferative activity of recombinant trans-10, cis-12 conjugated linoleic acid Microbiology, August 1, 2007; 153(8): 2483 - 2490. [Abstract] [Full Text] [PDF]

				J. H. Kim, J. Hwangbo, N.-J. Choi, H. G. Park, D.-H. Yoon, E.-W. Park, S.-H. Lee, B.-K. Park, and Y. J. Kim Effect of Dietary Supplementation with Conjugated Linoleic Acid, with Oleic, Linoleic, or Linolenic Acid, on Egg Quality Characteristics and Fat Accumulation in the Egg Yolk Poult. Sci., June 1, 2007; 86(6): 1180 - 1186. [Abstract] [Full Text] [PDF]

				N. E. Hubbard, D. Lim, and K. L. Erickson Conjugated Linoleic Acid Alters Matrix Metalloproteinases of Metastatic Mouse Mammary Tumor Cells J. Nutr., June 1, 2007; 137(6): 1423 - 1429. [Abstract] [Full Text] [PDF]

				I. Platt, L. G. Rao, and A. El-Sohemy Isomer-Specific Effects of Conjugated Linoleic Acid on Mineralized Bone Nodule Formation from Human Osteoblast-LikeCells Experimental Biology and Medicine, February 1, 2007; 232(2): 246 - 252. [Abstract] [Full Text] [PDF]

				E. Poole and C. E. McQueen Conjugated linoleic acid. Am. J. Health Syst. Pharm., November 1, 2006; 63(21): 2056 - 2062. [Full Text] [PDF]

				P. Bergamo, D. Luongo, F. Maurano, G. Mazzarella, R. Stefanile, and M. Rossi Conjugated linoleic acid enhances glutathione synthesis and attenuates pathological signs in MRL/MpJ-Faslpr mice J. Lipid Res., November 1, 2006; 47(11): 2382 - 2391. [Abstract] [Full Text] [PDF]

				W. Suksombat, S. Samitayotin, and P. Lounglawan Effects of conjugated linoleic acid supplementation in layer diet on fatty acid compositions of egg yolk and layer performances. Poult. Sci., September 1, 2006; 85(9): 1603 - 1609. [Abstract] [Full Text] [PDF]

				M. M. Rahman, A. Bhattacharya, and G. Fernandes Conjugated linoleic acid inhibits osteoclast differentiation of RAW264.7 cells by modulating RANKL signaling J. Lipid Res., August 1, 2006; 47(8): 1739 - 1748. [Abstract] [Full Text] [PDF]

				R. Siddiqui, D. Pandya, K. Harvey, and G. P. Zaloga Nutrition Modulation of Cachexia/Proteolysis Nutr Clin Pract, April 1, 2006; 21(2): 155 - 167. [Abstract] [Full Text] [PDF]

				H. J. Cho, E. J. Kim, S. S. Lim, M. K. Kim, M.-K. Sung, J.-S. Kim, and J. H. Y. Park Trans-10,cis-12, Not cis-9,trans-11, Conjugated Linoleic Acid Inhibits G1-S Progression in HT-29 Human Colon Cancer Cells J. Nutr., April 1, 2006; 136(4): 893 - 898. [Abstract] [Full Text] [PDF]

				J. M. Arbones-Mainar, M. A. Navarro, S. Acin, M. A. Guzman, C. Arnal, J. C. Surra, R. Carnicer, H. M. Roche, and J. Osada Trans-10, cis-12- and cis-9, trans-11-Conjugated Linoleic Acid Isomers Selectively Modify HDL-Apolipoprotein Composition in Apolipoprotein E Knockout Mice J. Nutr., February 1, 2006; 136(2): 353 - 359. [Abstract] [Full Text] [PDF]

				J. S.W. Taylor, S. R.P. Williams, R. Rhys, P. James, and M. P. Frenneaux Conjugated Linoleic Acid Impairs Endothelial Function Arterioscler. Thromb. Vasc. Biol., February 1, 2006; 26(2): 307 - 312. [Abstract] [Full Text] [PDF]

				G. Li, D. Barnes, D. Butz, D. Bjorling, and M. E. Cook 10t,12c-conjugated linoleic acid inhibits lipopolysaccharide-induced cyclooxygenase expression in vitro and in vivo J. Lipid Res., October 1, 2005; 46(10): 2134 - 2142. [Abstract] [Full Text] [PDF]

				T. D. Brandebourg and C. Y. Hu Isomer-specific regulation of differentiating pig preadipocytes by conjugated linoleic acids J Anim Sci, September 1, 2005; 83(9): 2096 - 2105. [Abstract] [Full Text] [PDF]

				D. V Aminot-Gilchrist and H. D. Anderson Insulin resistance--associated cardiovascular disease: potential benefits of conjugated linoleic acid Am. J. Clinical Nutrition, June 1, 2004; 79(6): 1159S - 1163S. [Abstract] [Full Text] [PDF]

				C. G Taylor and P. Zahradka Dietary conjugated linoleic acid and insulin sensitivity and resistance in rodent models Am. J. Clinical Nutrition, June 1, 2004; 79(6): 1164S - 1168S. [Abstract] [Full Text] [PDF]

				R. S McLeod, A. M LeBlanc, M. A Langille, P. L Mitchell, and D. L Currie Conjugated linoleic acids, atherosclerosis, and hepatic very-low-density lipoprotein metabolism Am. J. Clinical Nutrition, June 1, 2004; 79(6): 1169S - 1174S. [Abstract] [Full Text] [PDF]

				M. O'Shea, J. Bassaganya-Riera, and I. C. Mohede Immunomodulatory properties of conjugated linoleic acid Am. J. Clinical Nutrition, June 1, 2004; 79(6): 1199S - 1206S. [Abstract] [Full Text] [PDF]

				P. Degrace, L. Demizieux, J. Gresti, J.-M. Chardigny, J.-L. Sebedio, and P. Clouet Hepatic Steatosis Is Not Due to Impaired Fatty Acid Oxidation Capacities in C57BL/6J Mice Fed the Conjugated trans-10,cis-12-Isomer of Linoleic Acid J. Nutr., April 1, 2004; 134(4): 861 - 867. [Abstract] [Full Text] [PDF]

				G. Bernal-Santos, J. W. Perfield II, D. M. Barbano, D. E. Bauman, and T. R. Overton Production Responses of Dairy Cows to Dietary Supplementation with Conjugated Linoleic Acid (CLA) During the Transition Period and Early Lactation J Dairy Sci, October 1, 2003; 86(10): 3218 - 3228. [Abstract] [Full Text] [PDF]

				C. Corino, S. Magni, G. Pastorelli, R. Rossi, and J. Mourot Effect of conjugated linoleic acid on meat quality, lipid metabolism, and sensory characteristics of dry-cured hams from heavy pigs J Anim Sci, September 1, 2003; 81(9): 2219 - 2229. [Abstract] [Full Text] [PDF]

				C. A. Avramis, H. Wang, B. W. McBride, T. C. Wright, and A. R. Hill Physical and Processing Properties of Milk, Butter, and Cheddar Cheese from Cows Fed Supplemental Fish Meal J Dairy Sci, August 1, 2003; 86(8): 2568 - 2576. [Abstract] [Full Text] [PDF]

				N. Tsuboyama-Kasaoka, H. Miyazaki, S. Kasaoka, and O. Ezaki Increasing the Amount of Fat in a Conjugated Linoleic Acid-Supplemented Diet Reduces Lipodystrophy in Mice J. Nutr., June 1, 2003; 133(6): 1793 - 1799. [Abstract] [Full Text] [PDF]

				X. Xu, J. Storkson, S. Kim, K. Sugimoto, Y. Park, and M. W. Pariza Short-Term Intake of Conjugated Linoleic Acid Inhibits Lipoprotein Lipase and Glucose Metabolism but Does Not Enhance Lipolysis in Mouse Adipose Tissue J. Nutr., March 1, 2003; 133(3): 663 - 667. [Abstract] [Full Text] [PDF]

				M. Yang and M. E. Cook Dietary Conjugated Linoleic Acid Decreased Cachexia, Macrophage Tumor Necrosis Factor-{alpha} Production, and Modifies Splenocyte Cytokines Production Experimental Biology and Medicine, January 1, 2003; 228(1): 51 - 58. [Abstract] [Full Text] [PDF]

				S. R. Demaree, C. D. Gilbert, H. J. Mersmann, and S. B. Smith Conjugated Linoleic Acid Differentially Modifies Fatty Acid Composition in Subcellular Fractions of Muscle and Adipose Tissue but Not Adiposity of Postweanling Pigs J. Nutr., November 1, 2002; 132(11): 3272 - 3279. [Abstract] [Full Text] [PDF]