Incorporation Of Conjugated Linoleic Acid Research Articles

Synthesis and Structural Analysis of Structured Triacylglycerols with CLA Isomers in the sn‐2‐ Position

AbstractThe present research deals with the chemical esterification of the sn‐2‐ position of sn‐1,3‐diacylglycerol (sn‐1,3‐DAG) with 9cis,11trans (c9,t11) and 10trans,12cis (t10,c12) conjugated linoleic acid (CLA) isomers to obtain structured triacylglycerols (TAG); the sn‐1,3‐DAG substrates were produced from extra virgin olive oil by means of enzymatic reactions while CLA isomers were obtained using a three‐step procedure based on alkaline hydrolysis of sunflower oil, urea purification of linoleic acid (LA) and alkaline isomerization of LA. The results showed good levels of CLA incorporation in structured TAG at the tested temperatures: 37.5% at 4 °C and 39.1% at 14 °C. To evaluate the incorporation of CLA isomers in sn‐2‐ position of sn‐1,3‐DAG structural analysis of the newly synthesized TAG was carried out using an enzymatic and a chemical method. The results of the structural analysis also showed up the occurrence of acyl migration. The pancreatic lipase method allowed the direct determination of the fatty acid composition of TAG sn‐2‐ position but this enzymatic method showed different results (p < 0.05) in respect to the chemical one; this occurrence could be due to an acylic specificity of the lipase. High incorporation of CLA isomers in sn‐2‐ position of TAG was observed, 77.0% at 4 °C and 81.5% at 14 °C, considering the results of the chemical procedure.

The effects of conjugated linoleic acid (CLA) and canola oil on the fatty acid composition and quality of eggs from laying hens

Dietary conjugated linoleic acid (CLA) causes adverse effects on quality of eggs by modifying the fatty acid composition of the yolk. Supplementing oils prevent CLA-induced changes, but cause a decrease in the level of egg CLA. The objective of the study was to investigate the incorporation of CLA into the egg and its effect on the fatty acid metabolism when laying hens were fed diets containing different levels of canola oil. Hens (15 per group) were assigned to six groups and were fed for 50 days diets containing 0.5% canola oil (Group A), 0.5% CLA (Group B), 0.5% CLA plus 1.25% canola oil (Group C), 0.5% CLA plus 2.5% canola oil (Group D), 0.5% CLA plus 5% canola oil (Group E) or 0.5% CLA plus 10% canola oil. Eggs were collected daily. Three eggs per group were used for fatty acid analysis. Eggs laid on days 1 to11 were stored at 4 °C or room temperature for 30 days, and were separated into yolk and albumen for pH analyses. Yolk from Group B had increased concentrations of C16:0 and C18:0 and decreased concentrations of C18:1(n-9) compared to Group A. Adding 5% or 10% canola oil (Groups E or F) to the diet prevented an increase in C16:0 and C18:0 and a decrease in C18:1(n-9) concentrations. Relative amounts of CLA in eggs from Groups A, B, C, D, E and F were 0, 2.38, 2.33, 1.68, 1.36, and 1.17%, respectively. The concentrations of C18:3(n-3) in Groups A, B, C, D, E and F were 0.23, 0.25, 0.61, 0.70, 1.23 and 1.58%, respectively. The ratios of UFA/SFA in the eggs from Groups B, C and D decreased. When the eggs were stored at 4 °C, the yolk from Groups B, C and D had higher pH values than the other treatments, while the albumen pH of eggs from Groups B, C and D were lower. However, when eggs were stored at room temperature, no abnormal pH changes were observed in the yolk or albumen. This study suggested that adding a certain level of canola oil rich in n-3 fatty acids restored the level of egg yolk SFA to UFA, prevented CLA-induced abnormal changes in egg quality and thus led to a higher level of C18:3(n-3) and CLA in the egg. Keywords : Conjugated linoleic acid; unsaturated fatty acids; egg yolk and albumen pH; chickens South African Journal of Animal Sciences Vol. 35 (3) 2005: pp.172-179

Instrumental measurement of the texture of hard-boiled egg yolks enriched with different levels of conjugated linoleic acid

There is increased interest in enhancing the conjugated linoleic acid (CLA) content of food products because of its potential health benefits. Inclusion of CLA in the diets of laying hens has led to the incorporation of CLA into eggs, changes in yolk fatty acid (FA) composition and non-acceptable greater firmness of hard-boiled egg yolks. This study was designed to develop instrumental tests to determine the texture characteristics of hard-boiled egg yolks obtained from hens fed diets supplemented with different levels of CLA and other fat sources. Two compression tests have established relationship between some FA levels added to diets and the firmness of boiled egg yolks. There were significant differences in the compression parameters among egg yolks from laying hens fed diets supplemented with 3 and 5 g/kg of CLA (without other fats in diet) and commercial egg yolks. Supplementations with 30 and 35 g/kg of high oleic sunflower oil (HOSO) in diets which included 3 g/kg of CLA, decreased compression parameters to levels similar to commercial eggs.

CHEMICAL COMPOSITION AND FATTY ACID CONTENT OF BUFFALO CHEESE FROM NORTHWEST ARGENTINA: EFFECT ON LIPID COMPOSITION OF MICE TISSUES

ABSTRACT Chemical properties, long chain fatty acid composition and conjugated linoleic acid (CLA) content of buffalo cheese were determined. Good nutritional properties were observed in cheese, showing 11.5% of protein, 18.3% of fat and 30.5% of dry matter. Saturated fatty acid content was 65.6%, monounsaturated fatty acid was 31.8% and polyunsaturated was 2.6%. Stearic (C16:0) and oleic (C18:1) acids were the major fatty acids (FAs) present in milk and cheese. Values slightly higher of CLA were determined in cheese (4.5 and 5.2 mg/g of fat, respectively), being cis‐9,trans‐11, the predominant isomer. Mice provided with cheese showed higher CLA levels in fat tissues than animals from the control group. The cis‐9,trans‐11 isomer was incorporated into lipid tissues in great proportion than trans‐10,cis‐12. Total FA content was higher in mice fed cheese, but polyunsaturated fatty acid (linoleic + linolenic + CLA) in tissues was similar (0.6 mg/g of tissue) in all groups.PRACTICAL APPLICATIONSBuffalo milk products are widely consumed in Europe, especially as mozzarella cheese. In Northwest Argentina, buffalo was recently introduced for milk production, and no studies are available about chemical characteristics and fatty acid content of cheeses. The nutritional importance of many fatty acids, such as trans, has been widely stressed in recent years. Among this, conjugated linoleic adics (CLAs)] seem to have many biological effects on health, such as anticarcinogenic properties. Studies on CLA content in foods are being carried out as a way to offer to consumers the best source of this fatty acid. In the present study we demonstrated that buffalo milk and cheese represents a good source of CLA for humans, having as a major isomer the cis9, trans11. Its consumption affects the CLA incorporation into many tissues, offering cheese a higher CLA concentration than milk.

Enzymatic transesterification of fractionated rice bran oil with conjugated linoleic acid: Optimization by response surface methodology

Abstract Rice bran oil (RBO) was fractionated at a low temperature (−16 °C) and the yield of fractionated solid (S-RBO) and liquid (L-RBO) phase were 66.5 and 33.5 g/100 g, respectively. The L-RBO contained more unsaturated fatty acids (81.8%) than S-RBO (76.1%). Response surface methodology (RSM) was used to determine the effects of three variables (water activity of lipase, reaction temperature and time) on the lipase catalyzed incorporation of conjugated linoleic acid (CLA) into L-RBO. We used CLA as the acyl due to its purported health benefits. The transesterified lipid (TL) contained palmitic (13.5%), oleic (37.5%), linoleic (26.6%) and CLA isomers (20.7%), respectively. According to ridge analysis, optimal reaction conditions for water activity of lipase, reaction temperature and time were 0.177, 55.66 °C and 29.25 h, respectively, for producing TL with maximum incorporation of CLA. The coefficient of determination (R2=0.94) showed that the fitted model explained 94% of the observation. The TL was reproduced to confirm the experimental incorporation with the estimated value. The data showed that the experimental response was reasonably close to the estimated response. These results suggested that RSM can be used to optimize lipase-catalyzed incorporation of CLA into the fractionated L-RBO.

Mechanisms of body fat modulation by conjugated linoleic acid (CLA)

Since its discovery as an anticancer principal from ground beef extract in the 1980s, conjugated linoleic acid (CLA) has drawn much attention due to its variety of biological activities. One of the most interesting aspects of CLA is its ability to reduce body fat while enhancing lean body mass. One explanation for the variety of biological activities of CLA is that CLA is a mixture of geometric and positional isomers, although the primary research focus is on the two main isomers, cis-9,trans-11 and trans-10,cis-12. The involvement of eicosanoid metabolism has been suggested as one mechanism for CLAs wide range of biological activities. Incorporation of CLA in the sn-2 position of phospholipid fractions, and the negative correlation between tissue levels of CLA and arachidonic acid support this. Other possible mechanisms of CLA with regard to body fat reduction will be discussed, as well as differences between human and animal studies. Safety concerns regarding the use of CLA in humans are not conclusive and need further investigation.

Incorporation of conjugated linoleic acid and vaccenic acid into lipids from rat tissues and plasma

AbstractThe objective of this study was to determine the incorporation of conjugated linoleic acid (CLA) into triacylglycerols (TAG) and phospholipids (PL) of tissues and plasma, and to interpret the role of dietary‐derived vaccenic acid (VA) in increasing the tissue content of CLA (c9,t11) and the influence on the fatty acid profile. We fed five groups of rats semi‐purified diets with varying levels of CLA and VA: control butter with low CLA (c9,t11) and VA; control butter added 5% CLA (c9,t11); control butter added 5% Tonalin [equal amount of CLA (c9,t11) and CLA (t10,c12)]; control butter added 5% VA; butter with high CLA (c9,t11) and VA (H‐CLA), for 3 weeks. The highest incorporation of CLA (c9,t11) was found in adipose tissue, and the lowest was observed in liver. Low intake of CLA (c9,t11) combined with high intake of VA resulted in a higher incorporation of CLA (c9,t11) in tissues due to the conversion of VA to CLA (c9,t11), compared to feeding CLA (c9,t11) without VA. However, in enterocytes, the proportion of CLA (c9,t11) was low after feeding VA, indicating no or only a minor conversion of VA to CLA (c9,t11) in the intestine. The incorporation of CLA (t10,c12) into TAG from plasma and tissues was generally much lower than that of the CLA (c9,t11) isomer, except in the enterocyte TAG, which had similar proportions of the two isomers.

Effects of Conjugated Linoleic Acid Supplementation in Layer Diet on Fatty Acid Compositions of Egg Yolk and Layer Performances

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid with conjugated double bonds. Conjugated linoleic acids have been reported to have a wide range of health-beneficial effects, including anticarcinogenic, antiatherogenic, anti-diabetic, and immune stimulatory effects. The objective of this study was to investigate the incorporation of CLA into eggs. Three hundred 27-wk-old layers were allocated to 5 dietary treatments (0, 1, 2, 3, and 4% CLA) with 5 replicates. The results of the study showed that average daily feed intakes were similar in all treatment groups, although hens fed with 4% CLA tended to consume less feed than other hens. Body weight gain and mortality rate were not significantly different (P > 0.05). Hens fed 4% dietary CLA had reduced egg, yolk, and albumen weights (P < 0.05). Yolk color significantly decreased as dietary CLA increased (P < 0.01). Shell thickness and Haugh units were not influenced by the dietary CLA. Concentrations of CLA and saturated fatty acids in egg yolk lipids increased as dietary CLA increased (P < 0.01), whereas concentrations of monounsaturated fatty acids and polyunsaturated fatty acids decreased as dietary CLA increased (P < 0.01). It can be concluded from the present experiments that increasing the amount of CLA fed to hens will increase the amount of CLA in egg yolk and that this increase is accompanied by a reduction in the amount of yolk polyunsaturated fatty acids but an increase in yolk saturated fatty acids. Egg size, yolk weight, and Roche-fan determined yolk color significantly decreased at the highest level of CLA supplementation.

Enzyme‐catalyzed synthesis of structured phospholipids with conjugated linoleic acid

Structured phospholipids were synthesized with the functional lipid conjugated linoleic acid (CLA). The lipase- and phospholipase A 2 -catalyzed enzymatic acidolysis reaction between phospholipids (PL) and CLA was used for fatty acid modification. Enzymatic processes were an effective way to produce structured PL. Screening of four lipases and immobilized phospholipase A 2 and a combination of lipase and phospholipase showed that only Lipozyme RM IM and Lipozyme TL IM were effective in incorporation of CLA into PL. The maximum incorporation achieved by the latter enzyme was 16% with soy PL in 72 h.

Physicochemical and Volatile Characterization of Structured Lipids from Olive Oil Produced in a Stirred‐tank Batch Reactor

ABSTRACT: Structured lipid (SL) from conjugated linoleic acid (CLA) with olive oil was produced, and the physicochemical and volatile characterizations were investigated. In SL‐olive oil, 21.8 mol% of CLA isomers were incorporated, and the removal of tocopherols (63% loss from original olive oil) and chlorophylls (50% loss) was observed. The distinct exothermal peaks observed became broader, and the position of the peak shifted to a lower temperature in SL‐olive oil compared with normal olive oil. Reverse‐phase (ODS column) high‐performance liquid chromatography with an evaporative light‐scattering detection separated the newly synthesized SL‐triacylglycerols (TAGs), in which the incorporation of CLA into olive oil increased the content of TAGs with partition number &lt;48 from 9% (in olive oil) to 78% (SL‐olive oil). Total amount of volatile compounds in SL‐olive oil was smaller than those in olive oil, indicating removal of flavor compounds from olive oil occurred during the processes.

Contribution of conjugated linoleic acid to the suppression of inflammatory responses through the regulation of the NF-kappaB pathway.

Data from a number of researchers have shown that conjugated linoleic acid (CLA) has some beneficial health activities in animal models. Because inflammatory responses are associated with pathophysiology of many diseases, the aim of this study is to explore the effect and mechanism of CLA in the regulation of lipopolysaccharide (LPS)-induced inflammatory responses in RAW 264.7 macrophages. The addition of increasing levels of CLA proportionally augmented the incorporation of CLA in cultures. CLA diminished LPS-induced mRNA and protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2) as well as subsequent production of nitric oxide and prostaglandin E(2), respectively. We further examined the effect of CLA on LPS-induced NF-kappaB activation by Western blot and the electrophoretic mobility shift assay. The addition of CLA at 200 microM significantly diminished LPS-induced protein expression of the cytoplasmic phosphorylated inhibitor kappaBalpha and nuclear p65 as well as NF-kappaB nuclear protein-DNA binding affinity. In conclusion, our data suggest that CLA may inhibit LPS-induced inflammatory events in RAW 264.7 macrophages and this inhibitory activity of CLA, at least in part, occurs through CLA modulating the NF-kappaB activation and therefore negatively regulating expression of inflammatory mediators.

Effects of lipid-esterified conjugated linoleic acid isomers on platelet function: evidence for stimulation of platelet phospholipase activity

The effects of four conjugated linoleic acid (CLA) isomers on in vitro collagen-induced human platelet aggregation and thromboxane (TXB 2, the inactive metabolite of the proaggregatory TXA 2) production were examined. As the free fatty acid (FFA), 9t, 11t-CLA was the most effective inhibitor of these two processes (I 50s of 2.2 and 4 μM, respectively) and the 9c, 11c-CLA was the least effective (I 50s of 8.3 and 37 μM) of the isomers tested. When platelets were preesterified with either 25 μM 9t, 11t-CLA or 9c, 11c-CLA, CLA incorporation in total platelet lipids increased from 0.24% to 0.31% and 0.38%, and most of this increase was found to be in the phosphatidyl choline and phosphatidyl ethanolamine subclasses. The decrease in arachidonic acid (AA) content in total fatty acids or phospholipids was an order of magnitude greater. Furthermore, no significant differences between platelets prelabeled with either 9t, 11t- or 9c, 11c-CLA in the inhibition of collagen-induced aggregation and TXB 2 formation were observed. However, platelets prelabeled with 9c, 11c-CLA stimulated basal TXB 2 production (4-fold) which was not observed with platelets pretreated with either 9t, 11t-CLA, linoleic acid or stearic acid. This enhancement was associated with a 2.4–5-fold increase in the release of endogenous AA. Our results suggest that the presence of a conjugated cis, cis double bond appears to change the lipid environment sufficiently to stimulate the basal platelet phospholipase activity, which in turn increases the formation of TXB 2.

Effect of conjugated linoleic acid on meat quality, lipid metabolism, and sensory characteristics of dry-cured hams from heavy pigs.

We investigated conjugated linoleic acid (CLA) supplementation administered to heavy pigs, assessing carcass characteristics, meat quality, and sensory characteristics of dry-cured (Parma) ham. Thirty-six pigs, averaging 97 kg BW, were assigned randomly to three feeding groups in which diets were supplemented with either 0, 0.25, or 0.5% (as-fed basis) of a CLA preparation containing 65% CLA isomers. All pigs were slaughtered at 172 kg BW. No (P > 0.05) differences were observed in dressing percentage, loin and ham weight, or pH and color of longissimus and semimembranosus muscle. Tenth-rib backfat thickness tended to be lower (P < 0.10) in carcasses from CLA-fed pigs. The oxidative stability of longissimus muscle was greater (P < 0.05) in pigs fed CLA than control, but only at the longer (300 min) oxidation time. Acetyl-CoA carboxylase activity in adipose tissue of CLA-fed pigs was less (P < 0.05) than that of pigs fed diets devoid of supplemental CLA. Composition of ham fat was markedly affected (P < 0.01) by dietary CLA, with higher saturated fatty acids, lower monounsaturated fatty acids, and higher CLA in the fat of CLA-fed pigs regardless of supplementation level. Although melting quality was improved (P < 0.05), most sensory characteristics and the chemical composition of dry-cured hams were not (P > 0.05) affected by incorporation of CLA. Results indicated that dietary CLA alters lipid metabolism, producing lower concentrations of monounsaturated fatty acids and increased concentrations of CLA isomers in the fat of heavy pigs. Moreover, supplementing diets with CLA produced only minimal improvements in Parma ham sensory traits and had no appreciable effects on fresh pork quality.

Conjugated linoleic acid exhibits stimulatory and inhibitory effects on prostanoid production in human endothelial cells and platelets

In addition to their reported antitumorigenic properties, various conjugated linoleic acid (CLA) isomers have also been shown to decrease prostanoid synthesis as a result of inhibiting the cyclooxygenase (COX) enzyme. We have previously reported that several CLA isomers inhibited both platelet aggregation and formation of thromboxane A 2 (TXA 2), a proaggregatory and vasoconstrictive agent. Since the interaction between platelets and vascular endothelial cells is essential to maintaining vascular homeostasis, we decided to investigate the effects of various CLA isomers on the production of endothelial prostacyclin (PGI 2), a potent vasodilator and inhibitor of platelet function. Using interleukin 1-β (IL1-β)-stimulated human umbilical vein endothelial cells (HUVECs), we initially established that HUVECs of passage #2 should be used since these cells were most responsive to thrombin-induced conversion of endogenous arachidonic acid to PGI 2, as monitored by the formation of its stable, inactive metabolite, 6-ketoPGF 1α. In the first part of the study, the effects of CLA isomers in the free fatty acid form were tested. The 10( E), 12( Z)- and 9( Z), 11( E)-CLA isomers inhibited thrombin-induced 6-ketoPGF 1α formation with I 50's of 2.6 and 5.5 μM, whereas the 9( Z), 11( Z)- and 9( E), 11( E)-CLA were ineffective at concentrations up to 60 μM. The inhibitory effect of the 10( E), 12( Z)-CLA was irreversible. Next, the effects of CLA incorporation into HUVECs on PGI 2 generation was determined. An average 8-fold stimulation of 6-ketoPGF 1α formation was obtained with quiescent IL1-β-exposed HUVECs pretreated for 18 h with 25 μM 9( Z), 11( Z)-CLA, whereas cells preincubated with the 10( E), 12( Z) isomer enhanced this eicosanoid 3-fold. Such IL1-β-treated HUVECs prelabeled with 25 μM 9( Z), 11( Z)-CLA became refractory to thrombin stimulation, as measured by 6-ketoPGF 1α production, whereas a small, statistically insignificant, inhibition was observed upon thrombin treatment of HUVECs prelabeled with the 10( E), 12( Z) isomer. Qualitative similar results were obtained with resting or thrombin-stimulated platelets containing these esterified CLA isomers indicating that these effects occur with cells that contain either the COX-1 or COX-2 isozymes. The results of this in vitro study indicate that the effects of CLA on cellular prostanoid formation in endothelial cells and platelets can be either inhibitory or stimulatory, and this seems to depend not only on the specific CLA isomer and whether or not the CLA is in the free fatty acid form or esterified into cellular lipids, but also whether cells are in the resting or stimulated state. These findings suggest that in vivo, CLA might have multiple, complex effects on vascular homeostasis.

Dietary conjugated linoleic acid alters hepatic lipid content and fatty acid composition in broiler chickens

We examined the effect of dietary conjugated linoleic acid (CLA) on growth performance and liver composition in broiler chickens. Day-old male broiler chicks were assigned to receive a diet supplemented with corn oil (5%; n = 48) or CLA (5%; n = 48) for 21 d. Broilers fed CLA weighed less and grew at slower rates than broilers fed corn oil. Feed intake and feed conversion were higher for the corn-oil group than for the CLA dietary group. Hepatic lipid and triacylglycerol concentrations were significantly reduced by dietary CLA. The proportions of saturated fatty acids (SFA) in liver lipids increased, whereas those of monounsaturated fatty acids (MUFA) decreased with CLA supplementation. Although the total concentration of polyunsaturated fatty acids (PUFA) did not change with dietary treatment, the concentration of linoleic acid as a percentage of total methylated fatty acids decreased, and that of linolenic add increased in broilers fed CLA. The concentration of CLA isomers in liver lipids increased substantially with CLA feeding. The relative proportion of the c9,t11 CLA isomer in hepatic lipids was much higher than that of the t10,c12 or t9,t11 CLA isomers. These studies provide evidence that feeding CLA to broilers results in substantial reduction in liver fat accumulation and promotes CLA incorporation into hepatic lipid pools.

Lipase‐catalyzed incorporation of conjugated linoleic acid into tricaprylin

AbstractThree commercially available immobilized lipases, Novozym 435 from Candida antarctica, Lipozyme IM from Rhizomucor miehei, and Lipase PS‐C from Pseudomonas cepacia, were used as biocatalysts for the interesterification of conjugated linoleic acid (CLA) ethyl ester and tricaprylin. The reactions were carried out in hexane, and the products were analyzed by gas‐liquid chromatography. The effects of molar ratio, enzyme load, incubation time, and temperature on CLA incorporation were investigated. Novozym 435, as compared to Lipozyme IM and Lipase PC‐C, showed the highest degree of CLA incorporation into tricaprylin. By hydrolysis with pancreatic lipase, it was found that Lipozyme IM and Lipase PS‐C exhibited high selectivity for the sn‐1,3 position of the triacylglycerol early in the interesterification, with small extents of incorporation of CLA into the sn‐2 position, probably due to acyl migration, at later reaction times. A small extent of sn‐1,3 selectivity during interesterification by Novozym 435 was observed.

Transesterification of conjugated linoleic acid and tricaprylin by lipases in organic solvents

Lipase-catalyzed transesterification of tricaprylin with conjugated linoleic acid (CLA) ethyl ester was performed to produce triacylglycerols containing conjugated linoleic acid. Six commercially available lipases, and seven solvents were screened for their ability to incorporate CLA into tricaprylin. The transesterification reaction was performed by incubating a 1:2 mole ratio of tricaprylin and CLA ethyl ester in 3 ml solvents at 55°C, and the products were analyzed by gas chromatography. Three lipases, Novozym 435, Lipozym IM and lipase PS-C were chosen to allow a comparison of transesterification activity in our model reaction. The highest CLA incorporation with Novozym 435 and Lipozym IM was achieved in hexane while isooctane produced the highest CLA incorporation with lipase PS-C. Lipase PS-C gave higher CLA incorporation into tricaprylin when fatty acid was used as the acyl donor than other lipases did. Lipozym IM and lipase PS-C had not restrict specificity to sn-1, 3 positions, even though they had high specificity at sn-1, 3 positions. Novozym 435 among lipases tested was the most effective on the incorporation of CLA into tricaprylin.

Changes in conjugated linoleic acid and its metabolites in patients with chronic renal failure

Conjugated linoleic acid (CLA) is a mixture of isomers of linoleic acid with conjugated double bonds that constitutes the most abundant fatty acid with conjugated dienes (CDs) in humans. CLA, erroneously considered in the past as a product of lipoperoxidation, has a dietary origin and has shown to possess anticarcinogenic and anti-atherogenic activity, mainly in animal studies. CLA can be metabolized to conjugated linolenic acid (CD18:3) and to conjugated eicosatrienoic acid (CD20:3) and these metabolites may be implicated in CLA activity. Because of the presence of dyslipidemia and the high incidence of cardiovascular and neoplastic diseases in uremic patients, we evaluated CLA and its metabolites in these patients in order to evaluate their metabolism and site distribution. We measured CLA, CD18:3, CD20:3, CD fatty acid hydroperoxides (lipoperoxidation products), and linoleic acid in the plasma, adipose tissue, and red blood cell (RBC) membranes by using high-pressure liquid chromatography in the following groups: (1) 23 chronic renal failure (CRF) patients with creatine clearance (CCr)> 10 mL/min (26.2 +/- 16.7); (2) 21 end-stage CRF patients in conservative treatment with CCr <10 mL/min (6.8 +/- 1.8); (3) 30 hemodialysis (HD) patients; and (4) 30 healthy controls. The incorporation of CLA, CD18:3, and CD20:3 in RBC membranes was significantly reduced in group 1 and was even more reduced in groups 2 and 3. CLA significantly increased both in the plasma and adipose tissue of end-stage CRF patients only. CD18:3 and CD20:3 did not change in the plasma and adipose tissue of any group. No significant changes in linoleic acid and CD fatty acid hydroperoxides were found. The alterations of CD in CRF patients are not due to lipoperoxidation. The increased levels of CLA in plasma and adipose tissue of end-stage CRF patients may be due either to a reduced metabolization of CLA to CD18:3 and CD20:3, or to an altered site distribution with reduced incorporation in cellular membranes and accumulation in the plasma and adipose tissue. The clinical significance of these changes remains to be investigated.

Dietary Conjugated Linoleic acid (CLA) in House Fly, Musca domestica, with no Adverse Effects on Development

Conjugated linoleic acid (CLA) acts as a potent cancer inhibitor and biological modulator in several animal models by incorporation in the lipid fractions. Now we report the possibility of incorporation of dietary CLA into insect body lipids. Chemically-synthesized CLA from safflower seed oil was supplied to house fly ( Musca domestica) larvae and adults with diet supplements at various levels. Amount of CLA in the pupa and adult body was proportional to the concentrations of CLA in the diet. CLA amount in pupae and adults was 0.17 mg/g and 0.41 mg/g of body, respectively, by 0.1% CLA diet (the lowest dosage), whereas it dramatically increased to 3.05 mg/g and 1.51 mg/g of body, respectively, by 10% CLA diet (the highest dosage). The dietary CLA did not show any adverse effects on the development of larvae and pupae, survivorship and fertility of adults, and eclosion of deposited eggs.

Isomers of Conjugated Linoleic Acid (CLA) Are Incorporated into Egg Yolk Lipids by CLA-Fed Laying Hens

This study was designed to determine the amount of conjugated linoleic acid (CLA) incorporated into egg lipids after dietary CLA supplementation. Single Comb White Leghorn laying hens (n = 40; 28 wk old) were randomly assigned to four treatments of varying CLA levels (0, 0.01, 0.5 and 1 g CLA/kg diet). Eggs were collected daily for 36 d. Feed consumption and body weight were monitored. CLA content of egg yolk lipid was analyzed by gas-liquid chromatography. Birds fed 0.5 and 1.0 g CLA/kg feed had significantly more CLA in the egg yolk lipid vs. control and 0.01 g CLA/kg diet groups after 7 d (P < 0.0004). Incorporation of CLA into egg lipid was highest on d 24 and 36. CLA enrichment in egg lipid in the 1.0 g CLA/kg diet group was similar to that in ruminant animal food products, approximately 3 mg CLA/g fat.