Lymphatic transport of a physical mixture of medium-and long-chain TAG in rats

Lymphatic transport of a mixture of medium-chain TAG (MCT) and long-chain TAG (LCT) was studied in lymph-cannulated rats. Animals were administered a test emulsion containing either triolein, tricaprylin, or a 1∶1 mixture of triolein and tricaprylin, and the lymph was collected for 24 h. The lymphatic recovery rate of medium-chain FA (MCFA) was significantly higher in rats given the TAG mixture than in those given MCT alone. The lymphatic recovery rate of long-chain FA (LCFA) also was significantly higher in rats given the TAG mixture than in those given LCT alone. No TAG containing three MCFA (i.e., MCT) was detected, and 37.7% of TAG containing one or two MCFA was detected in the lymph TAG when rats were given the TAG mixture. These results indicate that lymphatic transport of MCFA and LCFA can be modified by the combination of MCT and LCT.     

Effects of dietary triacylglycerol structure on triacylglycerols of resultant chylomicrons from fish oil- and seal oil-fed rats

We investigated the influence of the intramolecular fatty acid distribution of dietary triacyl-sn-glycerols (TAG) rich in n-3 polyunsaturated fatty acids (PUFA) on the structure of chylomicron TAG. Fish oil and seal oil, comparable in fatty acid compositions but with different contents of major n-3 PUFA esterified at thesn-2 position (20:5n-3, 46.6%, and 5.3%; 22:6n-3, 75.5%, and 3.8%, respectively), were fed to rats. Mesenteric lymph was collected and the chylomicrons were isolated by ultracentrifugation. The fatty acid composition of chylomicrons largely reflected the fatty acid composition of the oils administered. The intramolecular fatty acid distributions of the TAG fed were reflected in the chylomicron TAG as the fraction of the total contents observed in thesn-2 position of 20:5n-3 were 23.6 and 13.3%, and of 22:6n-3 were 30.6 and 5.4% for resultant chylomicrons following fish oil and seal oil administration, respectively. Thus, after seal oil administration, significant higher load of n-3 PUFA was esterified in thesn-1,3 positions of chylomicron TAG compared with fish oil administration (P<0.05).     

Marine lipid-based liposomes increase <Emphasis Type="Italic">in vivo</Emphasis> FA bioavailability

Liposomes made from an extract of natural marine lipids and containing a high n-3 PUFA lipid ratio were envisaged as oral route vectors for FA supplements in order to increase PUFA bioavailability. The absorption of FA in thoracic lymph duct-cannulated rats, after intragastric feeding of dietary fats in the form of liposomes or fish oil, was compared. Lipid and FA analyses were also performed on feces. Five mole percent α-tocopherol was added to fish oil and incorporated into the liposome membrane. The influence of α-tocopherol on FA lymph recovery was also investigated. In vivo, FA absorption in rats was favored by liposomes (98±1%) compared to fish oil (73±6%). In the same way, the DHA proportion in lymph was higher after liposome ingestion (78%) than after fish oil ingestion (47%). However, phospholipid (PL) concentration in lymph was not affected by the kind of dietary fat ingested, suggesting a PL regulation due to de novo TAG synthesis. The influence of the intramolecular distribution of n-3 PUFA in dietary lipids (TAG and PL) on the intramolecular FA distribution in TAG of chylomicrons was also investigated. The results obtained showed that the distribution of n-3 PUFA esterified on the sn-2 of chylomicron TAG depended on the lipid source administered. All these results correlated, at least partly, with in vitro liposome behavior under conditions that mimic those of the gastrointestinal tract. As a whole, this study pointed out that marine PL may constitute an attractive material for the development of liposomes as oral PUFA supplements.     

Lipolysis of different oils using crude enzyme isolate from the intestinal tract of rainbow trout, <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>

Crude enzyme isolate was prepared from the intestine of rainbow trout. Positional specificity of the crude enzyme isolate was determined from both 1(3)- and 2-MAG products after in vitro lipolysis of radioactive-labeled triolein. The ratio of 2-MAG/1(3)-MAG was 2∶1, suggesting that the overall lipase specificity of the enzyme isolate from rainbow trout tended to be 1,3-specific; however, activity against the sn-2 position also was shown. In vitro lipolysis of four different unlabeled oils was performed with the crude enzyme isolate. The oils were: structured lipid [SL; containing the medium-chain FA (MCFA) 8∶0 in the sn-1,3 positions and long-chain FA (LCFA) in the sn-2 position], DAG oil (mainly 1,3-DAG), fish oil (FO), and triolein (TO). MCFA were rapidly hydrolyzed from the SL oil. LCFA including n−3 PUFA were, however, preserved in the sn-2 position and therefore found in higher amounts in 2-MAG of SL compared with 2-MAG of FO, DAG, and TO. Lipolysis of the DAG oil produced higher amounts of MAG than the TAG oils, and 1(3)-MAG mainly was observed after lipolysis of the DAG oil. The positional specificity determined and the results from the hydrolysis of the different oils suggest that n−3 very long-chain PUFA from structured oils may be used better by aquacultured fish than that from fish oils.     

Lymphatic fatty acids in canines dosed with pharmaceutical formulations containing structured triacylglycerols

The intramolecular structure of dietary triacylglycerols (TAG) influences absorption. In this study, two different pharmaceutical formulations were compared containing TAG differing in fatty acid profiles and intramolecular structures: LML and MLM, where M represented medium‐chain fatty acids (MCFA; 8:0) and L represented long‐chain fatty acids (LCFA). Lymph was collected from thoracic duct‐cannulated canines for 12 h and the fatty acid composition was determined. The lymphatic transport of total fatty acids was significantly higher than the amount dosed; hence, the small exogenously dosed lipid recruited a large pool of endogenous fatty acids. The LML vehicle led to a significantly higher total fatty acid transport than the MLM vehicle. The amount of 8:0 recovered in lymph was almost similar and low for both groups. The amount of LCFA recovered from the animals dosed with the LML vehicle was generally higher than from the animals dosed with the MLM vehicle; however, statistically significant differences were only found for 18:0 and 18:3n‐3. In conclusion, these results indicated that the fatty acid profile and intramolecular structure of administered TAG influenced the absorption of fatty acids in canines, also when the TAG was incorporated into a pharmaceutical formulation in low amounts.     

Evaluation of ethanolysis with immobilized Candida antarctica lipase for regiospecific analysis of triacylglycerols containing highly unsaturated fatty acids

The suitability of a recently proposed method based on ethanolysis with immobilized Candida antarctica lipase for regiospecific analysis of oils containing long-chain PUFA such as [PA and DHA has been evaluated using selected marine oils and regio-isomerically enriched synthetic TAG substrates. 1,3-Regios-electivity of the lipase was enhanced when the ethanolysis was conducted in a high excess of ethanol, typically 10–50 times by weight of the oil. This enabled the reaction to be conducted on a milligram scale. However, irrespective of the ethanol-to-oil ratio, C. antarctica lipase released FA from TAG at different rates depending on the degree of unsaturation and/or chain length of the FA. Differences in lipolysis rates were particularly significant for EPA and DHA, with EPA released faster than DHA. Although DHA can be measured with reasonable accuracy by ethanolysis with C. antarctica, the method requires further optimization before it can be adopted for reliable regiospecific analyses that are as accurate as those obtainable by ¹³C NMR analysis for all major FA occurring in oils rich in long-chain PUFA.     

Dietary long-chain PUFA in the form of TAG or phospholipids influence lymph lipoprotein size and composition in piglets

Several sources of long-chain PUFA (LCP) are currently available for infant formula supplementation. These oils differ in their FA composition, the chemical form of the FA esters [TAG or phospholipids (PL)], and presence of other lipid components. These differences may affect LCP absorption, distribution, and metabolic fate after ingestion. The purpose of this study was to evaluate the influence of different chemical forms of dietary LCP on the composition of lymph lipoproteins. Eighteen pigs (5 d old) were bottle-fed different diets for 2 wk: a control diet (C), a diet containing LCP as TAG from tuna and fungal oils (TF-TAG), or a diet containing LCP as PL from egg yolk (E-PL). We measured lipid and FA composition of lymph, main lymph fractions (TAG or PL), and the particle size of lymph lipoproteins. The average diameter of lymph lipoproteins was significantly lower in the E-PL group compared with the control and TF-TAG groups (C: 3902 +/- 384 A; TF-TAG: 3773 +/- 384 A; E-PL: 2370 +/- 185 A). Arachidonic acid and DHA contents in lymph and lymph-TAG were significantly higher in the TF-TAG group compared to the E-PL group (0.50 +/- 0.03 and 0.24 +/- 0.03 g/100 g vs. 0.29 +/- 0.04 and 0.12 +/- 0.03 g/100 g, respectively). The addition to the diet of LCP in the form of TAG or PL affected the size of intestinal lipoproteins and also led to a different distribution of these FA in lymph lipoproteins.     

Preparation of regioisomers of structured TAG consisting of one mole of CLA and two moles of caprylic acid

TAG (MLM) with medium-chain FA (MCFA) at the 1,3-positions and long-chain FA (LCFA) at the 2-position, and TAG (LMM) with LCFA at the 1(3)-position and MCFA at 2,3(1)-positions are a pair of TAG regioisomers. Large-scale preparation of the two TAG regioisomers was attempted. A commercially available FFA mixture (FFA-CLA) containing 9-cis, 11-trans (9c, 11t)- and 10t,12c-CLA was selected as LCFA, and caprylic acid (C₈FA) was selected as MCFA. The MLM isomer was synthesized by acidolysis of acyglycerols (AG) containing two CLA isomers with C₈FA: A mixture of AG-CLA/C₈ FA (1∶10, mol/mol) and 4 wt% immobilized Rhizomucor miehei lipase was agitated at 30°C for 72 h. The ratio of MLM to total AG was 51.1 wt%. Meanwhile, LMM isomer was synthesized by acidolysis of tricaprylin with FFA-CLA: A mixture of tricaprylin/FFA-CLA (1∶2, mol/mol) and 4 wt% immobilized R. miehei lipase was agitated at 30°C for 24 h. The ratio of LMM to total AG was 51.8 wt%. MLM and LMM were purified from 1,968 and 813 g reaction mixtures by stepwise short-path distillation, respectively. Consequently, MLM was purified to 92.3% with 49.1% recovery, and LMM was purified to 93.2% with 52.3% recovery. Regiospecific analyses of MLM and LMM indicated that the 2-positions of MLM and LMM were 95.1 mol% LCFA and 98.3 mol% C₈ FA, respectively. The results showed that a process comprising lipase reaction and short-path distillation is effective for large-scale preparation of high-purity regiospecific TAG isomers.     

Lipase-Catalyzed Interesterification of Schizochytrium sp. Oil and Medium-Chain Triacylglycerols for Preparation of DHA-Rich Medium and Long-Chain Structured Lipids

DHA-rich medium and long-chain structured lipids (MLSL) were successfully synthesized by lipase-catalyzed interesterification of microbial oil from Schizochytrium sp. with medium-chain triacylglycerols (MCT) containing 99% of caprylic acid. Parameters that affected the reaction process were investigated and the conditions were selected as follows: lipase from Aspergillus oryzae, NS40086; reaction time, 8 hours; substrate molar ratio (MCT/microbial oil), 1:1; lipase load, 8 wt%; reaction temperature, 60 °C. Under these conditions, the proportions of MCT, MLSL, and long-chain triacylglycerols (TAG) in the final products were 12.5%, 62.8%, and 24.6%, respectively. The final product was then subjected to UPLC-MS/MS. Eighty-three types of TAG were identified, in which 54 types contained MCFA and MLSL species with relatively high contents were 22:6–8:0–8:0 (6.8%), 8:0–8:0–16:0 (7.5%), and 16:0–16:0–8:0 (7.5%). This product rich in MLSL with DHA and MCFA in the same TAG molecule is beneficial for fat digestion and absorption in infant and thus can increase the bioavailability of DHA at the molecular level.     

Recoveries of rat lymph FA after administration of specific structured <Superscript>13</Superscript>C-TAG

The potential of the specific structured TAG MLM [where M-caprylic acid (8∶0) and L=linoleic acid (18∶2n−6)] is the simultaneous delivery of energy and EFA. Compared with long-chain TAG (LLL), they may be more rapidly hydrolyzed and absorbed. This study examined the lymphatic recoveries of intragastrically administered L^*L^*, M^*M^*M^*, ML^*M, and ML^*L^* (where ^*=¹³C-labeled FA) in rats. Lymph lipids were separated into lipid classes and analyzed by GC combustion isotope ratio MS. The recoveries of lymph TAG 18∶2n-6 8 h after administration of L^*L^*L^*, ML^*M, and ML^*L^* were 38.6, 48.4, and 49.1%, respectively, whereas after 24 h the recoveries were approximately 50% in all experimental groups. The exogenous contribution to lymph TAG 18∶2n-6 was approximately 80 and 60% at maximum absorption of the specific structured TAG and L^*L^*L^*, respectively, 3–6 h after administration. The tendency toward more rapid recovery of exogenous long-chain FA following administration of specific structured TAG compared with long-chain TAG was probably due to fast hydrolysis. The lymphatic recovery of 8∶0 was 2.2% 24 h after administration of M^*M^*M^*. This minor lymphatic recovery of exogenous 8∶0 was probably due to low stimulation of chylomicron formation. These results demonstrate tendencies toward faster lymphatic recovery of long-chain FA after administration of specific structured TAG compared with long-chain TAG.     

Determining Ethyl Esters in Fish Oil with Solid Phase Microextraction and GC–MS

The long-chain polyunsaturated fatty acids (PUFA) found in fish oil, specifically eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) play an important part in human health. As a result, fish oil supplements are commonly consumed by people around the world. Supplements in the form of triacylglycerols (TAG) can be sold at a premium price, compared to those in the ethyl ester (EE) forms. Producers of TAG supplements require a simple, rapid method to determine the authenticity of their raw material. Here, we describe a method to quantify EE in fish oil using solid phase microextraction headspace analysis and GCMS. Despite the variation in linear ranges of the calibration curves with volatility of the EE, 30 individual FA were quantified including common saturated FA such as palmitic and stearic acid, as well as longer chain PUFA, such as EPA and DHA. The method was then applied to three commercial fish oils in the TAG form and two of the products were found to contain EE, with one containing EE above 1.5% w/w, indicating that contamination had occurred. With growing consumer interest in fish oil products, the method proposed here will help resolve future issues of authenticity in fish oils.     

Diet and lipoprotein oxidation: Analysis of oxidized triacylglycerols in pig lipoproteins

Oxidized lipoproteins have a recognized role in atherogenesis, but molecular-level research on oxidized lipids in lipoproteins and the effect of diet on these molecules have been limited. In the present study, the effects of three sunflower seed oil diets differing in oxidation levels (PV in oils 1, 84, and 223 mequiv O₂/kg) on lipoprotein lipid oxidation in growing pigs were investigated. The emphasis was on the investigation of oxidized TAG molecules found in chylomicrons and VLDL. A method based on RP-HPLC and electrospray ionization-MS was used for the analysis of oxidized TAG molecules. The baseline diene conjugation method was used for the estimation of in vivo levels of lipoprotein lipid oxidation. Several oxidized TAG structures were found in the samples. These products consisted of TAG molecules with a hydroxy, an epoxy, or a keto group attached to a FA, and of TAG molecules containing an aldehyde structure derived from a FA. The lipoprotein lipids and TAG were more oxidized in the pigs fed on the most oxidized oil compared with those fed on nonoxidized oil. Oxidation of dietary fat was reflected in the lipoprotein oxidation. New, detailed information on oxidized TAG molecules of chylomicrons and VLDL was obtained.     

Regioisomers of octanoic acid-containing structured triacylglycerols analyzed by tandem mass spectrometry using ammonia negative ion chemical ionization

Tandem mass spectrometry based on ammonia negative ion chemical ionization and sample introduction via direct exposure probe was applied to analysis of regioisomeric structures of octanoic acid containing structured triacylglycerols (TAG) of type MML, MLM, MLL, and LML (M, medium-chain fatty acid; L, long-chain fatty acid). Collision-induced dissociation of deprotonated parent TAG with argon was used to produce daughter ion spectra with appropriate fragmentation patterns for structure determination. Fatty acids constituting the TAG molecule were identified according to [RCO₂]⁻ ions in the daughter ion spectra. With the standard curve for ratios of [M-H-RCO₂H-100]⁻ ions corresponding to each [RCO₂]⁻ ion, determined with known mixtures of sn-1/3 and sn-2 regioisomers of structured TAG, it was possible to determine the proportions of different regioisomers in unknown samples. The method enabled quantification of MML- and MLM-type structured TAG. In the case of MLL- and LML-type TAG, it was possible to determine the most abundant regioisomer in the unknown mixture and estimate the proportions of regioisomers when there were more than 50% MLL-type isomers in the mixture.     

Positional distribution of decanoic acid: Effect on chylomicron and VLDL TAG structures and postprandial lipemia

Although medium-chain FA (MCFA) are mainly absorbed via the portal venous system, they are also incorporated into chylomicron TAG; therefore, the positional distribution of MCFA in TAG is likely to affect their metabolic fate. We studied chylomicron and VLDL TAG structures, as well as the magnitude of postprandial lipemia, after two oral fat loads containing decanoic acid (10∶0) predominantly at the sn-1(3),2 (MML) or at the sn-1,3 positions (MLM) of TAG in a randomized, double-blind, crossover clinical trial with 10 healthy, normal-weight volunteers. An MS-MS method was used to analyze TAG regioisomers. The position of decanoic acid in chylomicron TAG reflected its position in the TAG ingested, and TAG with none, one, two, or three decanoic acid residues were detected after ingestion of both fats. More (P<0.05) 30∶0 and 38∶1 TAG (acyl carbons:double bonds) and fewer 46∶5, 54∶5 and 54∶4 TAG were found in chylomicrons after ingestion of MML than after MLM. The VLDL TAG composition did not differ between the fat loads but did change (P<0.05) 2 to 6 h after ingestion of both fats. No statistical differences were seen between the fat loads in areas under the plasma, chylomicron, or VLDL TAG response curves or in FFA concentrations. Thus, the positional distribution of MCFA in TAG affects their metabolic, fate, but the magnitude of postprandial lipemia does not seem to be dependent on the positional distribution of MCFA in the ingested fat.     

Distribution of medium-chain FA in different lipid classes after administration of specific structured TAG in rats

Structured TAG (STAG) containing medium-chain FA (MCFA) in the sn-1,3 positions and essential FA in the sn-2 position were synthesized by lipase-catalyzed acidolysis. In our previous studies we found that part of the MCFA from STAG could be absorbed in the small intestine; however, it was unclear how they were absorbed. In order to get a better understanding of the metabolism of STAG to improve future design and application of STAG, in the present study lymph lipids collected after feeding STAG were fractionated into different classes and the FA composition of each lipid class was studied by GC after methylation to FAME. Caprylic acid was detected in the fraction of TAG only after administration of 1,3-dioctanoyl-2-linoleyl-sn-glycerol (8∶0/18∶2/8∶0), whereas lauric acid was detected in TAG, DAG, and FFA as well as phospholipids after administration of 1,3-didodecanoyl-2-linoleyl-sn-glycerol (12∶0/18∶2/12∶0). We conclude that the enterocyte has the ability to reacylate the MCFA into TAG and that the intestinal absorption of MCFA from STAG mainly occurs by resynthesis of TAG. Caprylic acid from STAG is not incorporated into phospholipids, whereas lauric acid from STAG can be incorporated into phospholipids.     

Lymphatic transport in rats of interesterified oils containing conjugated linoleic acids

In this study we examined the lymphatic transport in rats of FA after administration of interesterified oils containing CLA, with emphasis on the location of CLA and octanoic acid in the TAG. The oils were produced by enzymatic interesterification. Eight oils with different structures or FA profiles were examined in this study: MCM, CMC, OCO, and COC, where M was expected to be octanoic acid and O oleic acid. In group 1, C was CLA as a mixture of the two CLA isomers c9, t11 or t10, c12, and in group 2, C was mainly the isomer t10, c12. Rats were subjected to cannulation of the mesenteric lymph duct, and the following day they were intragastrically administered one of the oils and lymph samples were collected for 24 h. The lymphatic transport of total FA from 0 to 8 h in group 1 was significantly (P < 0.05) higher for the OCO-1 and the COC-1 oils than for the CMC-1 oil. Similarly, in group 2 the transport was higher for the OCO-2 oil than for the CMC-2 oil. The recovery of both of the CLA isomers examined was similar (50-70%) and independent of the isomer, oil structure, and FA profile, whereas more octanoic acid was recovered from the CMC oils than from the MCM oils. The results indicated that the FA profiles and the position of octanoic acid had only a minor influence on the absorption of CLA.     

Absorption of triglycerides with defined or random structure by rats with biliary and pancreatic diversion

Fat absorption may be compromised by pancreatic or bile insufficiency, resulting in low uptake of essential fatty acid and energy. Using a rat model of malabsorption, we examined the absorption of defined triglycerides with medium-chain fatty acids (MCFA) in thesn-1,3 positions and essential fatty acids in thesn-2 position (MLM) compared to other fats. The thoracic duct was cannulated for collection of lymph, and the common bile and pancreatic duct was cannulated to divert both the pancreatic juice and bile. The rats were given a single bolus of triglyceride as a taurocholate emulsion. Fat absorption was measured from collected lymph samples. The triglycerides administered were a defined triglyceride, MLM [mainly (8∶0/10∶0)-(18∶2n−6)-(8∶0/10∶0)], a similar triglyceride subjected to chemical randomization, a mixture of medium-chain triglycerides and soybean oil, and soybean oil, respectively. The first three triglycerides had approximately 36 wt% linoleic acid (18∶2n−6) content. Administration of defined triglyceride was followed by significantly higher lymphatic level (wt%) of 18∶2n−6 (P<0.01) as well as a relative enhancement in mol% of 18∶2n−6 (P<0.05) compared to the other triglycerides. Lymphatic absorption of MCFA was similar in the three first groups but not as efficient as for long-chain fatty acids. Our results indicate that defined triglycerides thus may provide a means to increase absorption of essential fatty acids in fat malabsorption, such as that seen in cystic fibrosis, or for pre-term infants. Honored Student presentation, 84th AOCS Annual Meeting & Expo, Anaheim, California.     

Triacylglycerol oxidation in pig lipoproteins after a diet rich in oxidized sunflower seed oil

The effects of two sunflower seed oil diets differing in oxidation levels (PV in oils 1 and 190 mequiv O₂/kg) on lipoprotein TAG and total lipid oxidation were investigated in growing pigs. For 2 wk, two groups of 10 pigs were fed either of the diets, after which blood samples were collected. A method based on RP-HPLC and electrospray ionization-MS was used for the analysis of oxidized TAG molecules in chylomicrons and VLDL. The baseline diene conjugation method was used for the estimation of in vivo levels of lipoprotein lipid oxidation. TAG molecules with a hydroxy, an epoxy, or a keto group attached to a FA, as well as TAG core aldehydes were detected in the samples. Typically, lipoprotein TAG and total lipids were more oxidized in the pigs fed on the oxidized oil compared with those fed on nonoxidized oil. Oxidation of dietary fat was thus reflected in the lipoprotein oxidation, which confirmed our earlier findings.     

Effect of continuous enteral medium-chain fatty acid infusion on lipid metabolism in rats

This study compared (i) the relative effects of long-chain triglycerides (LCT) and medium-chain triglycerides (MCT), (ii) the influence of amount of MCT, and (iii) the impact of medium-chain fatty acid position, on plasma and lymphatic triglycerides and portal vein free fatty acids. The animals were fed approximately at 250 kcal/kg · day for 20h. The lymph from lymphatic duct and blood from portal vein and systemic circulation were collected. The results showed that feeding 100% MCT for 20h was sufficiently long to reduce significantly the level of linoleic acid in portal vein fatty acids and plasma and lymph triglycerides. However, this alteration induced by MCT feeding was partially prevented by adding LCT to the diet. The level of arachidonic acid was significantly reduced in plasma triglycerides by any of the diets containing medium-chain fatty acids compared to 100% LCT. When feeding MCT only, palmitoleic acid, presumably reflecting de novo lipogenesis, was increased in lymphatic triglycerides and portal vein fatty acids. Total saturated fatty acids as a total percentage of total fatty acids were also significantly increased in plasma and lymphatic triglycerides and portal vein fatty acids. Thus, when linoleic acid is limiting, the conversion of MCT into long-chain fatty acids by de novo lipogenesis is likely to be an important metabolic route. Providing LCT with MCT or 2-monodecanoin appears to limit this pathway.     

Progress toward the production of long-chain polyunsaturated fatty acids in transgenic plants

Long-chain PUFA such as eicosapentaenoic and docosahexaenoic acids are prevalent in fish oils, and these compounds have been demonstrated to play important roles in human health and nutrition. In particular, these n−3/omega-3 long-chain PUFA provide protection from cardiovascular disease and a collection of symptoms (termed metabolic syndrome) associated with progression toward type 2 diabetes and obesity. Within Western populations, a large increase in the occurrence of these conditions represents a major public health concern. Unfortunately, both marine fish stocks and (consequentially) consumption of fish oils are in steep decline, limiting the protective role of long-chain PUFA in human health. One alternative approach to the provision of these health-beneficial FA is via their synthesis in transgenic plants. This review will describe recent advances in the production of transgenic plant oils nutritionally enhanced to produce long-chain PUFA.