Effects of conjugated linoleic acids on protein to fat proportions,fatty acids,and plasma lipids in broilers

In a performance trial, broiler chickens received 29 g per kg feed of a preparation containing 70% linoleic acid (LA) in the control treatment and another preparation containing approximately the same amount of conjugated linoleic acids (CLA) in the experimental treatment. Diets of CLA treatment contained 18 g CLA per kg feed. The CLA preparation contained the isomers cis‐9,trans‐11 and trans‐10,cis‐12 at a proportion 1:1, other CLA isomers were quantitively negligible. Performance parameters (weight gain and feed conversion ratio over a 42 day period) were not significantly influenced by CLA intake. However, fat content of liver, breast, and leg muscles was reduced and protein contents in liver and leg muscles were elevated significantly. Fat to protein ratios in the main edible parts were shifted in favour of protein in CLA treated animals. In all analysed tissue lipids the content of saturated fatty acids was increased and that of monounsaturated fatty acids was decreased significantly. At the same time CLA was incorporated in tissue lipids effectively reaching more than 10 g per 100 g of total fatty acids. With regard to isomers the cis‐9,trans‐11 isomer was found in higher concentrations in tissue lipid fractions compared to the trans‐10,cis‐12 isomer. It was concluded that nutrient repartitioning due to CLA intake described for other species is also valid for broilers. Using appropriate feeding strategies it is possible to produce CLA enriched food from broilers.     

The Health Promoting Properties of the Conjugated Isomers of α-Linolenic Acid

The bioactive properties of the conjugated linoleic acid (CLA) isomers have long been recognised and are the subject of a number of excellent reviews. However, despite this prominence the CLA isomers are not the only group of naturally occurring dietary conjugated fatty acids which have shown potent bioactivity. In a large number of in vitro and in vivo studies, conjugated α-linolenic acid (CLNA) isomers have displayed potent anti-inflammatory, immunomodulatory, anti-obese and anti-carcinogenic activity, along with the ability to improve biomarkers of cardio-vascular health. CLNA isomers are naturally present in high concentrations in a large variety of seed oils but can also be produced in vitro by strains of lactobacilli and bifidobactena through the activity of the enzyme linoleic acid isomerase on α-linolenic acid. In this review, we will address the possible therapeutic roles that CLNA may play in a number of conditions afflicting Western society and the mechanisms through which this activity is mediated.     

Fatty acid and conjugated linoleic acid isomer profiles in human milk fat

The fatty acid composition of 39 mature human milk samples from four Spanish women collected between 2 and 18 weeks during lactation was studied by gas chromatography. The conjugated linoleic acid (CLA) isomer profile was also determined by silver‐ion HPLC (Ag⁺‐HPLC) with three columns in series. The major fatty acid fraction in milk lipids throughout lactation was represented by the monounsaturated fatty acids, with oleic acid being the predominant compound (36–49% of total fatty acids). The saturated fatty acid fraction represented more than 35% of the total fatty acids, and polyunsaturated fatty acids ranged on average between 10 and 13%. Mean values of total CLA varied from 0.12 to 0.15% of total fatty acids. The complex mixture of CLA isomers was separated by Ag⁺‐HPLC. Rumenic acid (RA, cis‐9 trans‐11 C18:2) was the major isomer, representing more than 60% of total CLA. Trans‐9 trans‐11 and 7‐9 (cis‐trans + trans‐cis) C18:2 were the main CLA isomers after RA. Very small amounts of 8‐10 and 10‐12 C18:2 (cis‐trans + trans‐cis) isomers were detected, as were different proportions of cis‐11 trans‐13 and trans‐11 cis‐13 C18:2. Although most of the isomers were present in all samples, their concentrations varied considerably.     

Oxidative stability of conjugated linoleic acids relative to other polyunsaturated fatty acids

Contrary to current opinion, conjugated linoleic acids (CLA) as a mixture of several isomers have been previously shown to function as prooxidants in the form of free fatty acids and methyl esters in heated canola oil. Furthermore, CLA oxidizes considerably faster than linoleic acid. However, stability of CLA relative to other polyunsaturated fatty acids remains undetermined. The present study was therefore undertaken to examine the relative oxidation rate of CLA compared with that of linolenic acid (LNA), arachidonic acid (AA), and docosahexaenoic acid (DHA) in air at 90°C. CLA, both in the form of free fatty acids and triacylglycerols, were extremely unstable to the same extent as DHA, but they oxidized considerably faster than LNA and AA. The mechanism by which CLA were readily decomposed was probably due to formation of the unstable free-radical intermediate.     

Body Compositional Changes and Growth Alteration in Chicks from Hens Fed Conjugated Linoleic Acid

Effects of feeding conjugated linoleic acid (CLA) to hens on progeny chick development and composition at hatch (NHC) and three weeks of age (TWC) were assessed. CLA (0 or 0.5%, composed of mixed isomers of cis-9,trans-11 or trans-10,cis-12-CLA) was fed to hens with either safflower (SO) or olive oil (OO) (3 or 3.5%) to assure successful hatch for 2 weeks prior to collection for incubation. Maternal CLA feeding had no effect on hatchability, but improved egg fertility (p < 0.05). Maternal feeding of CLA with SO increased 21 day-old progeny growth, while CLA with OO decreased growth (oil*CLA, p < 0.05). In 25 day-old chicks (TWC), but not NHC, maternal CLA decreased the proportion of total body water (p < 0.05) and increased body ash (p < 0.05). While monounsaturated fatty acids were decreased and saturated fatty acids increased in eggs and NHC from hens fed CLA, no differences in fatty acid composition were observed in chicks at 25 days of age from hens fed CLA. Maternal CLA feeding resulted in the presence of c9,t11 and t10,c12-CLA in NHC, but only c9,t11 in the TWC. In conclusion, hens fed CLA led to improved fertility and altered body composition at 3 weeks of age.     

Alterations in CPT‐1 mRNA and fatty acid profile in hepatic cell lines in response to treatment with t10,c12‐ or c9,t11‐conjugated linoleic acid

Trans10,cis12‐conjugated linoleic acid (t10,c12‐CLA) increases liver weights and hepatic lipids in mice. The purpose of this study was to determine the effects of CLA isomers (t10,c12‐CLA or c9,t11‐CLA) and carnitine palmitoyl transferase‐1 (CPT‐1) inhibitors (etomoxir or hemipalmitoylcarnitinium) on CPT‐1 mRNA, fatty acid profile, and cholesterol synthesis in AML‐12 and HepG2 cells. t10,c12‐CLA was incorporated to a greater extent in both cell lines than c9,t11‐CLA. In addition, t10,c12‐CLA increased the free cholesterol content of AML‐12 and HepG2 cells four‐ and fivefold, respectively. Cells incubated with medium containing CPT‐1 inhibitors or t10,c12‐CLA had higher levels of mRNA for CPT‐1 in both cell lines, indicating an increased fatty acid oxidation in hepatic cell lines due to t10,c12‐CLA. Following treatment withdrawal, percentages of c9,t11‐CLA or t10,c12‐CLA remained elevated in cells initially treated with c9,t11‐CLA or t10,c12‐CLA, suggesting a potential for carryover effects of the CLA isomers. The results presented here demonstrate a potential role for t10,c12‐CLA in the modulation of hepatic fatty acid oxidation and cholesterol synthesis.     

The Production of Conjugated α-Linolenic, γ-Linolenic and Stearidonic Acids by Strains of Bifidobacteria and Propionibacteria

Conjugated fatty acids are regularly found in nature and have a history of biogenic activity in animals and humans. A number of these conjugated fatty acids are microbially produced and have been associated with potent anti-carcinogenic, anti-adipogenic, anti-atherosclerotic and anti-diabetogenic activities. Therefore, the identification of novel conjugated fatty acids is highly desirable. In this study, strains of bifidobacteria and propionibacteria previously shown by us and others to display linoleic acid isomerase activity were assessed for their ability to conjugate a range of other unsaturated fatty acids during fermentation. Only four, linoleic, α-linolenic, γ-linolenic and stearidonic acids, were converted to their respective conjugated isomers, conjugated linoleic acid (CLA), conjugated α-linolenic acid (CLNA), conjugated γ-linolenic acid (CGLA) and conjugated stearidonic acid (CSA), each of which contained a conjugated double bond at the 9,11 position. Of the strains assayed, Bifidobacterium breve DPC6330 proved the most effective conjugated fatty acid producer, bio-converting 70% of the linoleic acid to CLA, 90% of the α-linolenic acid to CLNA, 17% of the γ-linolenic acid to CGLA, and 28% of the stearidonic acid to CSA at a substrate concentration of 0.3 mg mL⁻¹. In conclusion, strains of bifidobacteria and propionibacteria can bio-convert linoleic, α-linolenic, γ-linolenic and stearidonic acids to their conjugated isomers via the activity of the enzyme linoleic acid isomerase. These conjugated fatty acids may offer the combined health promoting properties of conjugated fatty acids such as CLA and CLNA, along with those of the unsaturated fatty acids from which they are formed.     

Conjugated linoleic acids: Physiological effects in animal and man with special regard to body composition

Institute of Nutrition, Friedrich Schiller University of Jena, Jena, Germany In the last decade, conjugated linoleic acids (CLA) have been shown to have some beneficial (but also unfavourable) effects: anticarcinogenic properties, immune modulation, reduction of body fat and increase of lean body mass, normalisation of impaired glucose tolerance, promotion of fatty streak formation, and isomer‐specific effects. The research base on CLA has been derived almost exclusively from animal models, while some of the biological properties have been fairly well‐documented, others are still open to question. For about 5 years a lot of commercial CLA mixtures have been offered. These mixtures produced from linoleic acid‐rich oil like sunflower or safflower oil by alkali isomerization contained, besides cis‐9,trans‐11 and trans‐10,cis‐12 CLA isomers (about 20—40% of each), parts of cis,cis and trans,trans isomers as well. The quality of the recent products is significantly improved and they contain only two CLA isomers: cis‐9,trans‐11 and trans‐10,cis‐12. CLA play apparently a key role in regulating body composition. Several studies showed a reduction in body fat mass and a slight increase in lean body mass depending on the species. A possible explanation for the decrease of body fat may be a stimulation of lipolysis and a reduction of lipoprotein lipase activity in adipocytes. In adipose and muscle tissue a CLA‐stimulated increase of carnitine palmitoyltransferase activity resulting in an enhanced fatty acid oxidation was shown. There is evidence that CLA provide protection against cytokine‐induced (Tumour necrosis factor‐α, interleukin‐1) skeletal‐muscle catabolism (anabolic effect). The body composition modulating effects are most impressive in rodents and seem to become smaller in pigs and in humans. Data on humans are insufficient. Further research is essential to characterize the multifunctionality of CLA in humans, in order to identify the specific physiological mechanism of the biologically active isomers and to determine the optimal level of these isomers for beneficial effects.     

Dietary Supplementation of Calcium may Counteract Obesity in Mice Mediated by Changes in Plasma Fatty Acids

The scope of this study was to assess the impact of calcium and conjugated linoleic acid (CLA) supplementation on plasma fatty acid profiles and to evaluate potential synergistic effects of both compounds against dietary obesity. Mice separated into five experimental groups were followed: control (C), high-fat diet (HF), HF with calcium (Ca), HF plus CLA and HF with both Ca and CLA. Plasma metabolites and fatty acids were determined by commercial kits and gas chromatography, respectively. Both dietary calcium and CLA supplementation contributed to lower body fat gain under a HF diet. Maximum efficacy was seen with calcium; no additional effect was associated with the combined treatment with CLA. Plasma leptin, adiponectin and HOMA index were in accordance with an altered glucose/insulin homeostasis in the HF and HF + CLA groups, whereas control levels were attained under Ca-enriched diets. Plasma fatty acids showed minor changes associated to CLA treatment, but a high impact on PUFA was observed under Ca-enriched diets. Our results show that the mechanism underlying the anti-obesity effects of calcium supplementation is mediated mainly by changes in PUFA plasma profile. In addition, the lack of synergy on body weight reduction in combination with associated lipid profiles of calcium and CLA suggests that calcium may interfere with absorption and/or bioactivity of CLA, which can be of relevance when using CLA-fortified dairy products against human obesity.     

The Growth‐Inhibiting Effects of Beef Fatty Acids on MCF‐7 Cells Are Influenced Mostly by the Depot Location and Inconsistently by the Biohydrogenation Intermediate Content

Biohydrogenation intermediates (BHI) including conjugated linoleic acid (CLA) isomers are formed during ruminal biohydrogenation of polyunsaturated fatty acids (PUFA) in ruminants. Although many studies have examined the anticarcinogenic effects of CLA, few studies have reported the anticarcinogenic properties of BHI in their natural form found in dairy and beef fats. The present study compared the growth‐inhibitory effects of fatty acids from beef perirenal fat (PRF) or subcutaneous fat (SCF) with low or high levels of BHI in MCF‐7 human breast cancer cells. Cells were exposed for 72 h to media containing increasing doses (50 to 400 μM) of different beef fat treatments. Fatty‐acid analysis showed that BHI were readily incorporated into cell phospholipids (PL) in a treatment‐dependent manner, but higher BHI in PL did not consistently inhibit growth. Culturing with low‐BHI PRF or high‐BHI PRF did not lead to growth inhibition, but low‐BHI SCF inhibited growth, and inhibition was further increased by high‐BHI SCF. Other classes of fatty acids may, therefore, be interacting with BHI resulting in differential effects on growth inhibition in human breast cancer cells.     

Dietary n‐3 fatty acids reduce the delayed hypersensitivity reaction and antibody production more than n‐6 fatty acids in broiler birds

The splenocyte fatty acid profile and immune response of broiler chickens were investigated. One hundred and twenty day‐old broiler chicks were fed diets containing conjugated linoleic acid (CLA) (Diet I), sunflower oil (Diet II), flaxseed oil (Diet III) or fish oil (Diet IV). The total lipid content of the diets was 3.5%. Body weight and feed intake was higher (P <0.05) in Diet IV compared to Diets I, II and III. Birds fed Diet III and IV had a higher content of n‐3 fatty acids in splenocytes than those fed Diets I and II. Serum anti‐BSA immunoglobulin content was higher (P <0.05) in birds fed Diets III and IV, compared to those fed Diets I and II. Delayed type hypersensitivity response, measured as the wing web skin swelling reaction (thickness) to Mycobacterium butyricum injection (s.c.), increased (P <0.05) from 0.71 and 0.98 mm in Diets IV and III, respectively, to 1.19 and 1.41 mm in Diets I and II, respectively. The number of CD4⁺ and CD8⁺ blood lymphocytes and CD4⁺, CD8⁺ and IgM⁺ splenocytes did not differ (P >0.05) between treatment groups. N‐3 fatty acids increased production performances and antibody mediated responses, while n‐6 fatty acids and conjugated linoleic acid increased cell mediated responses in broiler birds.     

The Diversity of Health Effects of Individual <Emphasis Type="Italic">trans</Emphasis> Fatty Acid Isomers

There are multiple adverse effects of trans fatty acids (TFA) that are produced by partial hydrogenation (i.e., manufactured TFA), on CVD, blood lipids, inflammation, oxidative stress, endothelial health, body weight, insulin sensitivity, and cancer. It is not yet clear how specific TFA isomers vary in their biological activity and mechanisms of action. There is evidence of health benefits on some of the endpoints that have been studied for some animal TFA isomers, such as conjugated linoleic acid; however, these are not a major TFA source in the diet. Future research will bring clarity to our understanding of the biological effects of the individual TFA isomers. At this point, it is not possible to plan diets that emphasize individual TFA from animal sources at levels that would be expected to have significant health effects. Due to the multiple adverse effects of manufactured TFA, numerous agencies and governing bodies recommend limiting TFA in the diet and reducing TFA in the food supply. These initiatives and regulations, along with potential TFA alternatives, are presented herein.     

Retraction: Are conjugated linoleic acid (CLA) isomers good or bad trans fats?

Even though trans fatty acids (TFAs) are present in natural sources such as foods from ruminant origins, the development of partially hydrogenated vegetable oil contributed to a significant increase in total TFAs consumption in humans. Currently, TFA consumption is considered to be a risk factor for coronary heart diseases. Researchers are now starting to discover that not all TFAs behave in a similar manner, that is, isomer specificity may be found. Among non‐conjugated TFAs, plant originated TFAs (mainly elaidic and linolelaidic acids) are particularly linked to increased risk for coronary heart diseases, while animal originated TFAs (mainly vaccenic acid) are not. Among conjugated TFAs, two major isomers of conjugated linoleic acid (CLA), cis‐9, trans‐11 and trans‐10, cis‐12, show distinctive biological activities. A number of clinical trials of CLA with effects on body composition have been reported, but effects on coronary heart disease risk factors have been inconsistent. Meanwhile, safety concerns regarding CLA, in particular isomer specificity, have also been raised. Thus, it is critical to identify isomer specific effects of TFAs on particular risk factors, to determine their health impact.     

Direct Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLA) using Gold Catalysts

Supported gold catalysts, e.g., Au on Al₂O₃, Fe₂O₃, CeO₂, MnO₂, TiO₂, ZrO₂, activated carbon, titanium silicalite TS‐1, were prepared and used for the isomerization of linoleic acid (cis‐9,cis‐12‐octadecadienoic acid) to conjugated linoleic acids (CLA) in the presence of hydrogen at 165 °C in a batch reactor. The best results were obtained using a catalyst with 2 wt % Au on TS‐1, which exhibits a high selectivity (78 %) towards CLA. The two biologically active target CLA isomers, i.e., cis‐9,trans‐11‐CLA and trans‐10,cis‐12‐CLA, were the main products. During the isomerization of linoleic acid to CLA, consecutive reactions also took place. These were the hydrogenation of linoleic acid and CLA to monounsaturated octadecenoic acids and the further hydrogenation of monounsaturated acids to stearic acid. Thus, gold catalysts are capable of isomerizing linoleic acid to CLA and hydrogenating their double bonds to an extent that depends on the Au catalyst used.     

Dietary C18:1 trans fatty acids increase conjugated linoleic acid in adipose tissue of pigs

The effect of dietary C18:1 trans fatty acids on back fat composition in pigs was investigated with special emphasis on conjugated linoleic acids (CLA). A total of 12 × 4 siblings of Large White and Swiss Landrace breed were housed in groups and fattened from 22 to 103 kg live weight. Pigs were fed a control diet (barley, wheat, soybean meal) or experimental diets which consisted of the control diet with a 5% replacement of olein or stearin fractions of pork fat, or partially hydrogenated fat. The hydrogenated fat was rich in C18:1 trans fatty acids but contained only negligible amounts of CLA. In contrast olein and stearin fractions contained far less C18:1 trans fatty acids but some CLA. In the control diet no C18:1 trans fatty acids and only traces of CLA were detected. The partially hydrogenated fat led to the highest CLA content in back fat (0.44%). Intermediate amounts of CLA were measured in pigs fed the fractionated pork fat (0.22/0.23%). In pigs fed the control diet, also small amounts of CLA were detected. The results indicate that CLA may be produced by endogenous Δ9‐desaturation out of dietary trans vaccenic acid in pigs.     

Thermally induced formation of conjugated isomers of linoleic acid

Chemical pathways responsible of the conjugation of linoleic acid during heat treatments such as refining (deodorization), frying or cooking processes have been investigated. For this purpose, methyl linoleate was submitted to oxidative and non‐oxidative thermal conditions. The resulting degradation products were mainly composed of geometrical and conjugated fatty acid isomers. Oxidative conditions were obtained using tert‐butyl hydroperoxide under inert atmosphere, and air. The obtained results from both thermal oxidative conditions were compared to non‐oxidative thermal treatment. Higher levels of conjugated linoleic acid were found when linoleate was heated under oxidative conditions. Two distinct mechanisms responsible for the formation of CLA isomers are proposed and discussed. Evidence of formation of 9,11‐C18:2 and 10,12‐C18:2 acids from 9,12‐C18:2 by a free‐radical chain reaction is provided. The first step consists in the formation of a free radical by abstraction of an active bis‐allylic hydrogen. By delocalization of the initial free radical, two allylic free radicals were stabilized and converted into the corresponding CLA isomers via the abstraction of a hydrogen radical from other linoleic acid or oxygenated species. Kinetic observations confirmed the significance of the bimolecular mechanism. Moreover, the proposed mechanism is supported by several pieces of information from the literature on peroxidation of linoleic acid. Under pure thermal conditions and/or for diluted samples, a second pathway to the formation of CLA from heat‐treated linoleic acid is proposed via an intramolecular rearrangement of the pentadienyl structure. This thermal [1,3]‐sigmatropic rearrangement results in a mixture of 9,11 and 10,12 CLA isomers. The formed cis/trans CLA isomers were readily rearranged by a [1,5]‐sigmatropic shift to yield trans‐8,cis‐10 and cis‐11,trans‐13 CLA isomers, respectively.     

Egg Yolk as Means for Providing Essential and Beneficial Fatty Acids

The new American Dietary Guidelines now recommend optimizing the types of fat consumed instead of reducing or eliminating fat from the diet. Chicken eggs are a means to deliver essential and beneficial human dietary fatty acids (FA), and can be staple component of healthy eating behavior. Additionally, polyunsaturated fatty acids can be increased in the avian egg yolk by simply incorporating selected lipid sources into the avian diet. Poultry feed rich in omega‐3 FA (omega‐3) has allowed commercialization of enriched eggs containing up to 600 mg of omega‐3. Conjugated linoleic acid (CLA) has also been used in the research setting to enrich eggs to provide a portion of the 3–4 g CLA day^?1 needed to promote weight loss to combat obesity. However, Americans consume only 50% of the omega‐3 recommended adequate intake, and average CLA consumption is under 600 mg day^?1. While a variety of foods are naturally rich in omega‐3, conventional sources of CLA are limited to bovine milk and meat, which do not provide enough CLA to produce clinical effects in a balanced diet. Since eggs and egg‐based products are common in the Western diet, eggs enriched with both omega‐3 and CLA using dietary additions to poultry feed may promote consumption of the recommended levels of these FA. This article reviews the design of poultry eggs with enhanced lipid profiles through dietary intervention, and discusses the future direction of enriched egg research.     

Directed sequential synthesis of conjugated linoleic acid isomers from Δ7, 9 to Δ12, 14

Position and configuration isomers of conjugated linoleic acid (CLA), from 7, 9‐ through 12, 14‐C18:2, were synthesized by directed sequential isomerizations of a mixture of rumenic (cis‐9, trans‐11 C18:2) and trans‐10, cis‐12 C18:2 acids. Indeed, the synthesized conjugated fatty acids cover the range of unsaturated systems as found in milk fat CLA. The two‐step sequence consisted in initial sigmatropic rearrangement of cis/trans CLA isomers at 200 °C for 13 h under inert atmosphere (Helium, He), followed by selenium‐catalyzed geometrical isomerization of double bonds at 120 °C for 20 h under He. Product analysis was achieved by gas‐liquid chromatography using a 120 m polar capillary column coated with 70% cyanoalkylpolysiloxane equivalent polymer. Migration of conjugated systems was geometrically controlled as follows: the cis‐C_n, trans‐C_n+2 double bond system was rearranged through a pericyclic [1, 5] sigmatropic mechanism into a trans‐C_n‐1, cis‐C_n+1 unsaturated system, while the trans‐C_n, cis‐C_n+2 double bond system was rearranged through a similar pericyclic mechanism into a cis‐C_n+1, trans‐C_n+3 unsaturated system. Selenium‐catalyzed geometrical isomerization under mild conditions then allowed cis/trans double bond configuration transitions, resulting in the formation of all cis, all trans, cis‐trans and trans‐cis isomers. A sequential combination of the two reactions resulted in a facile controlled synthesis of CLA isomers, useful for the chromatographic identification of milk fat CLA, as well as for the preparation of CLA standard mixture.     

Fatty acid profiles in tissues of mice fed conjugated linoleic acid

The incorporation of vaccenic acid (VA, 0.5 and 1.2%), conjugated linoleic acid (CLA, mixture of primarily c9,t11‐ and t10,c12‐CLA, 1.2%), linoleic acid (LA, 1.2%) and oleic acid (OA, 1.2%) into different tissues of mice was examined. The effects on the fatty acid composition of triacylglycerols (TAG) and phospholipids (PL) in kidney, spleen, liver and adipose tissue were investigated. VA and CLA (c9,t11‐ and t10,c12‐CLA) were primarily found in TAG, especially in kidney and adipose tissue, respectively. Conversion of VA to c9,t11‐CLA was indicated by our results, as both fatty acids were incorporated into all the analyzed tissues when a diet containing VA but not c9,t11‐CLA was fed. Most of the observed effects on the fatty acid profiles were seen in the CLA group, whereas only minor effects were observed in the VA groups compared with the OA group. Thus, CLA increased n‐3 polyunsaturated fatty acids (PUFA) in PL from kidney and spleen and lowered the ratio of n‐6/n‐3 PUFA in these tissues. Furthermore, CLA increased C₂₂ PUFA in the PL fraction of kidney, spleen and liver, but reduced the level of arachidonic acid in PL of liver and spleen and lowered the Δ⁹‐desaturation indexes in all analyzed tissue TAG.     

Thraustochytrids as an alternative source of omega‐3 fatty acids,carotenoids and enzymes

Currently the most common microalgae used for commercial production of omega‐3 fatty acids are marine derived, particularly from family members of Thraustochytriaceae and Crypthecodiniaceae. Thraustochytrids are marine heterotrophic fungi like microorganisms known to produce several commercially interesting biotechnological compounds including omega‐3 fatty acids such as docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and eicosapentaenoic acid (EPA), carotenoids, sterols, exopolysaccharides and enzymes. Therefore, exploring the potential of thraustochytrids has much to offer to the commercial production of bioactive compounds. In response to growing demand for omega‐3 fatty acids, various isolation, fermentation and lipid recovery strategies have been developed in recent years.