Alternative lipids to usual omega 6 PUFAS: gamma-linolenic acid, alpha-linolenic acid, stearidonic acid, EPA, etc

Extraction techniques for bioactive compounds of cannabis

Historically, cannabis has always constituted a component of the civilized world; archaeological discoveries indicate that it is one of the oldest crops, while, up until the 19th century, cannabis fibers were extensively used in a variety of applications, and its seeds comprised a part of human and livestock nutrition. Additional evidence supports its exploitation for medicinal purposes in the ancient world. The cultivation of cannabis gradually declined as hemp fibers gave way to synthetic fibers, while the intoxicating ability of THC eventually overshadowed the extensive potential of cannabis. Nevertheless, the proven value of certain non-intoxicating cannabinoids, such as CBD and CBN, has recently given rise to an entire market which promotes cannabis-based products. An increase in the research for recovery and exploitation of beneficial cannabinoids has also been observed, with more than 10 000 peer-reviewed research articles published annually. In the present review, a brief overview of the history of cannabis is given. A look into the classification approaches of cannabis plants/species as well as the associated nomenclature is provided, followed by a description of their chemical characteristics and their medically valuable components. The application areas could not be absent from the present review. Still, the main focus of the review is the discussion of work conducted in the field of extraction of valuable bioactive compounds from cannabis. We conclude with a summary of the current status and outlook on the topics that future research should address.

Feeding habitat and silvering stage affect lipid content and fatty acid composition of European eel Anguilla anguilla tissues

Lipids, particularly fatty acids (FAs), are major sources of energy and nutrients in aquatic ecosystems and play key roles during vertebrate development. The European eel Anguilla anguilla goes through major biochemical and physiological changes throughout its lifecycle as it inhabits sea- (SW), and/or brackish- (BW) and/or freshwater (FW) habitats. With the ultimate goal being to understand the reasons for eels adopting a certain life history strategy (FW or SW residency vs. 'habitat shifting'), we explored differences in lipid content and FA composition of muscle, liver and eyes from eels collected across Norwegian SW, BW and FW habitats, and at different lifecycle stages (yellow to silver). FW and SW eels had a higher lipid content overall compared to BW eels, reflecting differences in food availability and life history strategies. SW eels had higher proportions of certain monounsaturated FAs (MUFAs; 18:1n-9, 20:1n-9), and of the essential polyunsaturated FAs 20:5n-3 (eicosapentaenoic acid, EPA) and 22:6n-3 (docosahexaenoic acid) than FW eels, reflecting a marine-based diet. In contrast, the muscle of FW eels had higher proportions of 18:3n-3, 18:2n-6 and 20:4n-6 (arachidonic acid), as is typical of FW organisms. MUFA proportions increased in later stage eels, consistent with the hypothesis that the eels accumulate energy stores prior to migration. In addition, the decrease of EPA with advancing stage may be associated with the critical role that this FA plays in eel sexual development. Lipid and FA information provided further understanding of the habitat use and overall ecology of this critically endangered species.

The Acute Respiratory Distress Syndrome: Role of Nutritional Modulation of Inflammation Through Dietary Lipids

The acute respiratory distress syndrome (ARDS) is the most serious form of acute hypoxic respiratory failure. ARDS represents the expression of an acute, diffuse, inflammatory process in the lungs consequent to a variety of infectious and noninfectious conditions. It is characterized pathologically by damage to pulmonary epithelial and endothelial cells, with subsequent alveolar-capillary leak and exudative pulmonary edema. The main clinical features of ARDS include rapid onset of dyspnea, severe defects in gas exchange, and imaging studies demonstrating diffuse pulmonary infiltrates. The role of nutrition in the management of ARDS has traditionally been supportive. Recent research has demonstrated the potential of certain dietary oils (eg, fish oil, borage oil) to modulate pulmonary inflammation, thereby improving lung compliance and oxygenation, and reducing time on mechanical ventilation. This article reviews the alterations in the immune response that underlie ARDS, discusses the physiology of dietary oils as immunonutrients, summarizes animal and human studies that explore the therapeutic effects of dietary oils, and provides clinical recommendations for their use.

Estrogen Enhances the Expression of the Polyunsaturated Fatty Acid Elongase Elovl2 via ERα in Breast Cancer Cells

Endocrine therapy is the first-line targeted adjuvant therapy for hormone-sensitive breast cancer. In view of the potential anticancer property of the omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) together with chemotherapy in estrogen receptor alpha (ERα) positive mammary tumors, we have explored the regulation by estradiol of the fatty acid desaturation and elongation enzymes involved in DHA synthesis in the human breast cancer cell line MCF7, which expresses ERα but not ERβ. We demonstrate a robust up-regulation in the expression of the fatty acid elongases Elovl2 and Elovl5 upon estradiol stimulation in MCF7 cells, which was sustained for more than 24 hours. Exposure with the ER inhibitor tamoxifen abolished specifically the Elovl2 but not the Elovl5 expression. Similarly, knock-down of ERα eliminated almost fully the Elovl2 but not the Elovl5 expression. Furthermore, ERα binds to one specific ERE within the Elovl2 enhancer in a ligand dependent manner. The involvement of ERα in the control of especially Elovl2, which plays a crucial role in DHA synthesis, may have potential implications in the treatment of breast cancer.

Formulation of multifunctional oil-in-water nanosized emulsions for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body

Oil-in-water (o/w) type nanosized emulsions (NE) have been widely investigated as vehicles/carrier for the formulation and delivery of drugs with a broad range of applications. A comprehensive summary is presented on how to formulate the multifunctional o/w NE for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body. The NE is classified into three generations based on its development over the last couple of decades to make ultimately a better colloidal carrier for a target site within the internal and external organs/parts of the body, thus allowing site-specific drug delivery and/or enhanced drug absorption. The third generation NE has tremendous application for drug absorption enhancement and for 'ferrying' compounds across cell membranes in comparison to its first and second generation counterparts. Furthermore, the third generation NE provides an interesting opportunity for use as drug delivery vehicles for numerous therapeutics that can range in size from small molecules to macromolecules.

Evidence for an association between genetic variants of the fatty acid desaturase 1 fatty acid desaturase 2 ( FADS1 FADS2) gene cluster and the fatty acid composition of erythrocyte membranes

The present study gives further evidence for the recently found association between variants of the fatty acid desaturase 1 fatty acid desaturase 2 (FADS1 FADS2) gene cluster and PUFA in blood phospholipids and explores this association for cellular fatty acids in erythrocyte membranes. In a subgroup of adults participating in the Bavarian Nutrition Survey II, a cross-sectional population-based study conducted in Bavaria, Germany, allelic variation in three selected loci of the FADS1 FADS2 gene cluster was analysed and used for haplotype construction. Associations with plasma phospholipid PUFA (n 163) and PUFA in erythrocyte membranes (n 535) were investigated by regression analysis. All haplotypes of the original five-loci haplotypes of our previous study could be replicated. In addition, associations with serum phospholipid PUFA were confirmed in the present data set. Although less pronounced, associations between FADS1 FADS2 haplotypes and PUFA in erythrocyte membranes, particularly arachidonic and dihomo-gamma-linolenic acid, could be established. We provide the first replication of the association of the FADS1 FADS2 gene cluster with PUFA in blood phospholipids. For the first time, such associations were also shown for PUFA in cell membranes.

Metabolic effects of intravenous LCT or MCT/LCT lipid emulsions in preterm infants

Most lipid emulsions for parenteral feeding of premature infants are based on long-chain triacylglycerols (LCTs), but inclusion of medium-chain triacylglycerols (MCTs) might provide a more readily oxidizable energy source. The influence of these emulsions on fatty acid composition and metabolism was studied in 12 premature neonates, who were randomly assigned to an LCT emulsion (control) or an emulsion with a mixture of MCT and LCT (1:1). On study day 7, all infants received [13C]linoleic (LA) and [13C]alpha-linolenic acid (ALA) tracers orally. Plasma phospholipid (PL) and triacylglycerol (TG) fatty acid composition and 13C enrichments of plasma PL fatty acids were determined on day 8. After 8 days of lipid infusion, plasma TGs in the MCT/LCT group had higher contents of C8:0 (0.50 +/- 0.60% vs. 0.10 +/- 0.12%; means +/- SD) and C10:0 (0.66 +/- 0.51% vs. 0.15 +/- 0.17%) than controls. LA content of plasma PLs was slightly lower in the MCT/LCT group (16.47 +/- 1.16% vs. 18.57 +/- 2.09%), whereas long-chain polyunsaturated derivatives (LC-PUFAs) of LA and ALA tended to be higher. The tracer distributions between precursors and products (LC-PUFAs) were not significantly different between groups. Both lipid emulsions achieve similar plasma essential fatty acid (EFA) contents and similar proportional conversion of EFAs to LC-PUFAs. The MCT/LCT emulsion seems to protect EFAs and LC-PUFAs from beta-oxidation.

Parenteral nutrition providing a restricted amount of linoleic acid in severely burned patients: a randomised double-blind study of an olive oil-based lipid emulsion v. medium/long-chain triacylglycerols

It has been claimed that lipid emulsions with a restricted linoleic acid content can improve the safety of total parenteral nutrition (TPN). The tolerability of TPN and its effects on the metabolism of fatty acids were assessed in this prospective, double-blind, randomised study comparing an olive/soyabean oil long-chain triacylglycerol (LCT) with a medium-chain triacylglycerol (MCT)/LCT; 50:50 (w) based lipid emulsion in two groups (O and M, respectively; eleven per group) of severely burned patients. After resuscitation (48-72 h), patients received TPN providing 147 kJ/kg per d (35 kcal/kg per d) with fat (1.3 g/kg per d) for 6 d Plasma fatty acids, laboratory parameters including liver function tests, and plasma cytokines were assessed before and after TPN. Adverse events encountered during TPN and the clinical outcomes of patients within the subsequent 6 months were recorded. With both lipid emulsions, the conversion of linoleic acid in its higher derivatives (di-homo-gamma-linolenic acid) improved and essential fatty acid deficiency did not appear. Abnormalities of liver function tests occurred more frequently in the M (nine) than in the O (three) group (P = 0.04, Suissa-Shuster test). Seven patients (four from group O and three from group M) died as a consequence of severe sepsis 3-37 d after completion of the 6 d TPN period. When compared with the surviving patients, those who died were older (P = 0.01) and hyperglycaemic at baseline (P < 0.001), and their plasma IL-6 levels continued to increase (P < 0.04). Although fatty acid metabolism and TPN tolerability were similar with both lipid emulsions, the preservation of liver function noted with the use of the olive oil-based lipid emulsions deserves confirmation.

Menopause-induced changes in lipid fractions and total fatty acids in plasma

The purpose of the present work was to evaluate the changes induced by the menopause in plasma lipids and total fatty acids.

METHODS

35 post-menopausal and 25 non-postmenopausal women were included in the study. Plasma triglycerides (TG), total cholesterol (TC) and HDL-C concentrations were detemined enzymatically. Plasma fatty acids were determined by capillary gas chromatography.

RESULTS

Total cholesterol was higher (p < 0.05) in the postmenopausal women (6.18 +/- 0.77 mmol/l vs. 5.21 +/- 0.85 mmol/l). No significant changes were observed, however, in TG, HDL-C or LDL-C. The study of plasma fatty acids showed the post-menopausal women to have raised levels (p < 0.05) of stearic acid (C18:0), oleic acid (C18:1), and decrease of arachidonic acid (C20:4). Also noteworthy was the significant decrease (p < 0.001) of the desaturation index D5 (3.82 +/- 1.75) in the post-menopausal women. The SHBG level was lower (p <0.001) in the post-menopausal women (55.98 +/- 20nmol/l) than in the non-menopausal women (68.36 +/- 30 nmol/l). Multivariate analysis revealed correlation between menopause and SHBG (r = -0.3904, p < 0.05), D5 (r = -0.500, p < 0.001), TC (r = 0.3137, p <0.05), stearic acid (r = 03564, p < 0.05) and oleic acid (r = 0.2954, p < 0.05).

CONCLUSION

In post-menopausal women, as well as higher total cholesterol, the alterations in plasma fatty acids may constitute an important risk factor for cardiovascular diseases.

Effect of dietary supplementation with black currant seed oil on the immune response of healthy elderly subjects

BACKGROUND

We have shown that the age-associated increase in prostaglandin E(2) production contributes to the decline in T cell-mediated function with age. Black currant seed oil (BCSO), rich in both gamma-linolenic (18:3n-6) and alpha-linolenic (18:3n-3) acids, has been shown to modulate membrane lipid composition and eicosanoid production.

OBJECTIVE

Our objectives were to 1) test whether dietary supplementation with BCSO can improve the immune response of healthy elderly subjects, and 2) determine whether the altered immune response is mediated by a change in the factors closely associated with T cell activation.

DESIGN

A randomized, double-blind, placebo-controlled (soybean oil) study was conducted to examine the effect of 2 mo of BCSO supplementation on the immune response of 40 healthy subjects aged >/=65 y. In vivo immune function was determined by delayed-type hypersensitivity skin response. Peripheral blood mononuclear cells (PBMCs) were tested for in vitro immune response.

RESULTS

In subjects supplemented with BCSO, the total diameter of induration at 24 h and individual responses to tetanus toxoid and Trichophyton mentagrophytes were significantly higher than their baseline values. The change in response to tetanus toxoid was significantly different from that of the placebo group. The BCSO group showed a significant increase in proliferative response of PBMCs to the T cell mitogen phytohemagglutinin that was not significantly different from that observed in the placebo group. BCSO had no effect on concanavalin A-induced mitogenic response, interleukin 2 and -1beta production, and PBMC membrane fluidity. Prostaglandin E(2) production was significantly reduced in the BCSO-supplemented group, and this change was significantly different from that of the placebo group.

CONCLUSION

BCSO has a moderate immune-enhancing effect attributable to its ability to reduce prostaglandin E(2) production.

Blood clearance and tissue uptake of intravenous lipid emulsions containing long-chain and medium-chain triglycerides and fish oil in a mouse model

BACKGROUND

Increasing interest in using different triglycerides (TGs) for specific clinical applications raised the question as to how the emulsion TG composition would affect blood clearance and emulsion delivery to hepatic and extrahepatic tissues.

METHODS

Emulsions used were long-chain soy oil TG (long-chain triglyceride [LCT]), LCT/ medium-chain triglyceride (MCT; 1:1, wt/wt), LCT/MCT/C/omega-3 (5:4:1, wt/wt) and pure fish oil (omega-3 TG) labeled with non-degradable 3H-cholesteryl oleoyl ether (3H-CE) as a particle marker. Mice (C57BL/6J) were injected with four different commercial emulsions at a nonsaturating dose of 0.4 mg TG/20 to 25 g per mouse to obtain 1st order kinetics. Blood was sampled at 0.5, 2, 5, 10, 15, and 25 minutes, and the fractional catabolic rate was determined by fitting a straight line to the logarithm of the blood 3H-CE radioactivity. Retention of 3H-CE for each tissue at 25 minutes reflected organ uptake of the emulsion.

RESULTS

Blood clearance of pure omega-3 TG (10.40% +/- 0.54% pools/h; mean +/- SE) was significantly slower than that of LCT, LCT/MCT, and LCT/MCT/omega-3 emulsion (18.9 +/- 0.6 pools/h, 17.0 +/- 0.96 pools/h, 16.5 +/- 1.08 pools/h, respectively) (p < .01). Based on 3H-CE uptake, LCT, LCT/MCT, and omega-3 TG emulsions showed similar delivery to liver (39% +/- 3.9%, 46% +/- 3.6%, 34% +/- 3.2%). Liver uptake of LCT/MCT/omega-3, (23% +/- 2.2%) was less than LCT/MCT (46% +/-3.6%, p < .0001) and LCT (39% +/- 3.9%, p = .002).

CONCLUSIONS

Results indicate slow blood clearance of pure omega-3 TG emulsion from the blood compared with emulsion in which omega-3 TG was mixed with LCT and MCT. Earlier data showed that omega-3 TG are poorly hydrolyzed in extracellular media and therefore are delivered to tissues as part of the core of emulsion remnants. Thus, our data suggest that the incorporation of omega-3 TG with LCT/MCT will result in greater delivery of omega-3 fatty acids to extrahepatic tissue, which could be important in modulating immune and other responses.

Fat emulsion administration in the early postoperative period in patients undergoing esophagectomy for carcinoma depresses arachidonic acid metabolism in neutrophils

The aim of this study was to evaluate the effect of fat emulsion administration on neutrophil arachidonic acid and leukotriene B4 (LTB4) generation in surgically stressed patients. Total parenteral nutrition was administered to 17 patients for 2 wk after esophagectomy for carcinoma. Eight patients received fat with glucose (fat group, 30% of total calories) and 9 patients received glucose (glucose group) as a non-protein calorie source from the day of the operation to the seventh postoperative day (POD), and they gradually were converted to enteral nutrition during the second postoperative week. The arachidonic acid in the fat group decreased in the serum from POD 4 to 14. and in neutrophils from 12 h after the beginning of surgery to POD 14, compared to preoperative levels. LTB4 production by A23187-stimulated neutrophils was highest 6 h after the beginning of surgery, when neutrophil arachidonic acid concentration was decreasing, and then fell below the preoperative value from POD 4 to 14 in both groups. LTB4 production on POD 14 was lower in the fat group than in the glucose group. Biosynthesis of arachidonic acid from linoleic acid is inhibited in surgically stressed patients receiving fat emulsion, resulting in the diminished synthesis of LTB4 by neutrophils. The decrease in LTB4 may diminish chemotactic and chemokinetic signals to other leukocytes.

Structure and metabolic fate of triacylglycerol- and phospholipid-rich particles of commercial parenteral fat emulsions

The lipid emulsions used in parenteral nutrition are constituted of particles rich in triacylglycerols (TAG) called artificial chylomicrons (200-500 nm in diameter; monolayer of phospholipids [PL] enveloping a TAG core) and PL-rich particles called liposomes (diameter inferior to 80 nm; bilayer of PL around an aqueous phase), which represent the excess emulsifier. Introduced into the circulation, the two populations of particles come into contact with circulating lipoproteins and cell membranes and experience the same overall fate: exchanges and transfers of lipids and apolipoproteins, enzymatic hydrolysis of TAG and PL, and internalization by different tissues. The relative importance of these different metabolic processes varies depending on the type of particle. The artificial chylomicrons undergo a hydrolysis of their TAG by lipoprotein lipase, with a release of fatty acids and formation of smaller particles of remnants, which are rapidly removed by the liver. In delivering fatty acids to the tissue, artificial chylomicrons fulfill an energy transport function similar to the natural chylomicrons. The liposomes hold little energy interest, and they also have deleterious effects when infused in excess. They inhibit the lipolysis of artificial chylomicrons and, by actively capturing endogenous cholesterol, they stimulate tissue cholesterogenesis and accumulate in the blood as lipoprotein-X, a long-lived abnormal lipoprotein. To limit as much as possible the metabolic perturbations due to the intravenous administration of exogenous PL, the emulsion has to be infused at a low rate, and should contain the minimal amount of excess PL.

Eicosanoids and fat emulsions in acute respiratory distress syndrome patients

Lipid emulsions have been associated with changes in pulmonary function. Although these changes were related to the physical effects of the infusion-induced lipemia on gas exchange, several animal and human studies suggest that the impairment in pulmonary function observed with lipid infusions was mediated by prostaglandins. Prostaglandins are synthesized enzymatically from essential fatty acids. We studied the effects of two lipid emulsions, with different amounts of essential fatty acids (20% long-chain triacylglycerols [LCT] with 55% of linoleic acid and 7% of alpha linolenic acid in 100 g of emulsion, and a physical mixture of 20% medium-chain triacyglycerols [MCT] and LCT with 26% of linoleic acid and 4% of alpha linolenic acid in 100 g of emulsion), on plasma levels of eicosanoids in patients with acute respiratory distress syndrome (ARDS). Although in patients with ARDS, plasma levels of prostanoids were higher than the reference values, neither lipid emulsion, administered at the rate of 2 mg.kg-1.min-1 induced significant changes in the eicosanoids except for a decrease in systemic-pulmonary arterial 6-keto prostaglandin F1 alpha difference.

Effect of diets containing different amounts of precursor and derivative fatty acids on serum TXB2

Dietary precursor and derivative polyunsaturated fatty acids influence metabolic parameters, such as eicosanoid synthesis. We have studied the effect of dietary intakes of lipids containing different amounts of precursor and derivative fatty acids (olive oil, olive-blackcurrant-fish oil mixture, blackcurrant-fish oil mixture, MCT (medium chain triglycerides)-soyabean oil mixture) on serum thromboxane B2 (TXB2) in four groups of rats. Plasma fatty acid composition showed differences related to dietary intakes. TXB2 levels were similar in all conditions except in the group receiving the mixture of olive-blackcurrant-fish oils which showed lower values.

The effect of parenteral fish oil on leukocyte membrane fatty acid composition and leukotriene-synthesizing capacity in patients with postoperative trauma

The incorporation of omega-3 and omega-6 fatty acids (FAs) into leukocyte membranes and the leukotriene (LT)B4-, LTB5 -, LTC4-, and LTCs-synthesizing capacity in stimulated leukocytes were measured following parenteral omega-3 FA nutrition in 20 postoperative patients. Total parenteral nutrition (TPN) over 5 days postoperatively was isonitrogenous (0.24 g N x kg-1 x d1) and isoenergetic (92 kJ/22 kcal x kg-1 x d-1), containing 0.15 g fish oil and 0.85 g soybean oil per kg-1 x d-1 (FO) or 1.0 g soybean oil x kg-1 x d-1 (SO). Following 5 days' FO administration, the content of eicosapentaenoic acid (EPA) was increased 2.5-fold, LTB5 1.5-fold, and LTC5 sevenfold. With SO nutrition, EPA and LTB5 generation remained unaltered, whereas LTC5 doubled. The production of LTB4 and LTC4 was not affected in any of the groups. We conclude that a 5-day parenteral fish oil supplementation has an immunomodulatory effect on lipid-mediator generation in human leukocytes in postoperative trauma.

The metabolic distinctiveness of emulsified lipid particles in the bloodstream and its clinical implications

The advantages of administering intravenous fat emulsions are well known. Primarily, they are important sources of essential fatty acids; they allow the administration of many calories within a small volume; and they are isotonic compared to body fluid. In this review, the metabolic distinctiveness of parenterally infused fat particles in the bloodstream is evaluated under four main headings: (1) the structure and metabolism of fat emulsion particles; (2) the metabolism of phospholipid-rich fat emulsion; (3) the interactions between fat emulsion particles and plasma lipoproteins; and (4) the acquisition of protein moieties (apolipoproteins) by fat emulsion particles and its clinical implications.

Essential fatty acid status in patients on long-term home parenteral nutrition

BACKGROUND

Patients on total parenteral nutrition are known to be at risk of the development of essential fatty acid deficiency, presenting as a syndrome with scaly skin lesions and characterized by low plasma and erythrocyte linoleic acid concentrations. The essential fatty acid status of patients on long-term home parenteral nutrition who do have access to oral feeds has not been studied.

METHODS

With the use of an isocratic high-performance liquid chromatography method, fatty acids were measured in the erythrocytes and plasma of 25 nonfasting patients on long-term home parenteral nutrition and the findings compared with those of 46 hospital outpatients not on nutrition support and five laboratory staff.

RESULTS

Statistically significant differences in the two groups were limited to the erythrocytes. Linoleic acid was significantly lower (25.2 vs 40.7 mumol/10(6) red blood cells, p < .0001) and showed a significant correlation with triceps skinfold thickness (r = .52, p = .013). Palmitoleic and oleic acids were higher in patients than controls (10.8 vs 8.4 mumol/10(6) red blood cells, p = .009; 61.2 vs 51.7 mumol/10(6) red blood cells, p = .003).

CONCLUSIONS

Despite IV linoleic acid administration, patients on long-term home parenteral nutrition have low erythrocyte stores of this essential fatty acid. This appears to be related to their low body fat stores. We suggest that they may be using much of the infused linoleic acid as an energy source and therefore are at risk of subclinical essential fatty acid deficiency.

Effect of three intravenously administered fat emulsions containing different concentrations of fatty acids on the plasma fatty acid composition of premature infants

The effects of an intravenously administered lipid emulsion supplemented with gamma-linolenic acid on the fatty acid profile of premature infants were compared with those of two conventional lipid emulsions. Fifty-nine premature neonates receiving total parenteral nutrition were randomly assigned to receive either fat emulsion containing gamma-linolenic acid and long-chain triglycerides (LCT), an LCT emulsion, or a 50% (wt/wt) mixture of medium-chain triglycerides and LCT emulsion. Forty-nine infants completed the study. During the 6-day study there was a significant tenfold increase in the plasma levels of gamma-linoleic acid in the supplemented group versus the other two groups. A significant threefold to fivefold increase in the omega 6 long-chain polyunsaturated fatty acids was observed in all groups. These changes seemed to be attributable mostly to linoleic acid from the lipid emulsion, despite the 50% lower dose in the medium- and long-chain triglycerides group. The increase in the omega 3 long-chain polyunsaturated fatty acids also was mainly caused by a similar increase in the level of alpha-linolenic acid. No differences were recorded in the linoleic/alpha-linolenic acid ratio among the groups. Plasma levels of some of the semiessential fatty acids were significantly higher in the medium- and long-chain triglycerides group than in the LCT group. This may be related to slower elimination of LCT, to the difference between emulsions, or to less substrate inhibition on delta-6-desaturase, which seems to be less of a rate-limiting enzyme than previously considered. Further intravenous feeding trials are needed to identify the optimal balance of fatty acids for nutrition of these premature infants.

Selective reduction of delta 6 and delta 5 desaturase activities but not delta 9 desaturase in micropigs chronically fed ethanol

This study investigated the mechanism by which chronic ethanol feeding reduces arachidonate and other highly unsaturated fatty acids in pig liver phospholipids. Five micropigs were fed a diet providing 89 kcal/kg body wt for 12 mo, with ethanol and fat as 40 and 34% of energy, respectively. Five control pigs were pairfed corn starch instead of ethanol. The activities of delta 6 and delta 5 desaturases (expressed as microsomal conversion of precursor to product) in liver from ethanol-fed pigs were reduced to less than half that of controls, whereas the activity of delta 9 desaturase was unaffected in the ethanol group. delta 5 Desaturase activity showed positive correlation with the abundance of its products in liver total phospholipids and microsomes in the ethanol group, but not in the controls. Correlation between delta 6 desaturase activity and its products showed similar pattern to that of delta 5 desaturase, but did not reach statistical significance. No difference was observed between the two groups in coenzyme A concentration in the liver. These results suggest that the selective reduction of delta 6 and delta 5 desaturase activities, not the microsomal electron transport system, are directly responsible for the altered profile of liver phospholipids.

Effects of essential fatty acid contents of lipid emulsions on erythrocyte polyunsaturated fatty acid composition in patients on long-term parenteral nutrition

The effect of the long-term intravenous infusion of 2 lipid emulsions, differing in essential fatty acid (EFA) content, on fatty acid pattern of red blood cell (RBC) was investigated in 5 patients with inflammatory bowel disease. They were randomly assigned to receive daily intravenous infusion of either a soybean emulsion or a mixed medium-chain triacyl-glycerols (MCT): soybean emulsion, followed by the other, each for a period of 3 months. The soybean emulsion contained exclusively long-chain triacylglycerols (LCT) with 54% of C18:2n-6 and 6% of C18:3n-3. The mixed emulsion consisted of a 50:50 (w:w) mixture of soybean LCT and MCT, providing half the amount of the same EFA compared to LCT emulsion. The same phospholipid emulsifier was used in both preparations. Infusion of LCT for a 3 month period modified RBC fatty acid pattern as follows: 18:2n-6 increased, 20:4n-6 decreased as well as n-6:n-3 ratio. By contrast, infusion of MCT/LCT did not alter RBC fatty acids, and even tended to correct a pattern altered by the previous LCT infusion. The study demonstrates that soybean LCT provides an excess of C18: 2n-6 which affects the balance between RBC fatty acids in adult patients. Decreasing the intake of C18:2n-6 and C18: 3n-3, by using a mixed MCT/LCT emulsion, appears more appropriate for keeping a balanced pattern.

Composition of phospholipid fatty acids in red blood cell membranes of patients in intensive care units: effects of different intakes of soybean oil, medium-chain triglycerides, and black-currant seed oil

Fatty acid composition of phospholipids in red blood cell membranes was studied in 32 severely head-injured or cerebral stroke patients receiving enteral nutrition for 3 weeks. During this study the effects of three diets differing only by their lipid composition were investigated. The daily energy intake of each patient amounted to 2950 kilocalories, of which the lipid fraction represented 45.7%. Diet A contained only soybean oil, diet B consisted of a 50% soybean oil and 50% medium-chain triglycerides mixture, and diet C was an emulsion of 50% soybean oil, 42.5% medium-chain triglycerides, and 7.5% black-currant seed oil. Our results showed no biochemical signs of fatty acid deficiency in red blood cell membranes for the patients at the beginning of the study, after a comparison with a control group of 20 healthy adults. Inhibition of delta 6-desaturase activity on linoleic acid (C18:2 omega 6) after diet A was suggested by an increase of linoleic acid without a corresponding increase of dihomo-gamma-linolenic acid (C20:3 omega 6). Replacing 50% of soybean oil by with medium-chain triglycerides (diet B) prevented this enzyme inhibition. Supply of black-currant seed oil rich in gamma-linolenic (C18:3 omega 6) and stearidonic (C18:4 omega 3) acids (diet C) induced significant increases of dihomo-gamma-linolenic and eicosapentaenoic (C20:5 omega 3) acids, without influencing arachidonic acid (C20:4 omega 6) levels. This balance was evaluated through the ratio (C20:3 omega 6 + C20:5 omega 3)/C20:4 omega 6.

Effect of various lipid emulsions on total parenteral nutrition-induced hepatosteatosis in rats

The effect of various lipid emulsions on the development of fatty liver during total parenteral nutrition (TPN) was investigated in rats given TPN for 7 days. Medium-chain triglycerides (MCT), long-chain triglycerides (LCT), chemically defined triglycerides (CDT; structured lipid with a high purity of 94.3%), and a mixture of MCT and LCT (MIX) were prepared as the lipid emulsions. TPN provided 350 kcal/kg/day, with a nonprotein calorie/nitrogen ratio of 160. The TPN-1 group received 10% nonprotein calories and the TPN-2 group received 30% nonprotein calories. MCT TPN was found to have some disadvantages, especially with regard to nitrogen balance and plasma albumin levels. Total cholesterol and phospholipids tended to be high in the MCT TPN group. The hepatic lipid content was higher in the lipid-free TPN and the MCT TPN groups, and lower in the CDT and LCT TPN groups. Histologically, the livers of the MIX, CDT, and LCT TPN groups showed less fatty change than those of the FREE and MCT groups.

Erythrocyte membrane lipid alterations in undernourished cerebral palsied children during high intakes of a soy oil-based enteral formula

Five undernourished children with severe cerebral palsy (CP) were tube-fed sufficient volumes of Isocal to allow rapid weight gain. Isocal provided, on average, 88% of their daily energy intake for at least 25 days. The purpose of our study was to correct the undernutrition and to analyze the major erythrocyte phospholipids before and after feeding periods for possible feeding and disease-related differences. The fatty acid profiles of erythrocyte membranes from CP children were compared with those from 12 healthy children and with the fatty acid composition of the formula. There were no clinical or biochemical indications of essential fatty acid deficiency. The feeding of a soy oil-based formula increased the proportions of 18:2n-6 in the phospholipids. The increases occurred predominantly in phosphatidylcholine followed by phosphatidylethanolamine. Despite such large dietary intakes of soy oil, no changes were observed in the phospholipid concentrations of 20:4n-6, 18:3n-3, 20:5n-3, or in the C22n-6 and C22n-3 fatty acids. These findings are consistent with an inhibition of the delta 6 desaturase by high dietary linoleate.

Phospholipid fatty acid composition of various mouse tissues after feeding alpha-linolenate (18:3n-3) or eicosatrienoate (20:3n-3)

The selective incorporation of dietary alpha-linolenate (18:3n-3) and its elongation product, eicosatrienoate (20:3n-3), into various phospholipids (PL) of mouse liver, spleen, kidney, and heart, was examined in a two-week feeding trial by assessing mol % changes in associated fatty acids. Mice were fed fat-free AIN 76A diets modified with either 2 wt% safflower oil (control); 1% safflower and 1% linolenate; or 1% safflower and 1% eicosatrienoate. After linolenate or eicosatrienoate feeding, 20:4n-6 was reduced by 36-50% in liver phosphatidylcholine (PC) and in liver and spleen phosphatidylethanolamine (PE). Linolenate was minimally incorporated into PL, but was desaturated and elongated to 20:5n-3, 22:5n-3, and 22:6n-3, with notable differences in the quantity of these n-3 derivatives associated with different tissues and PL. Eicosatrienoate was uniquely incorporated into the cardiolipin (CL) pool of all organs. There was also considerable retroconversion of 20:3n-3 to 18:3n-3 (PC,PE). Dietary eicosatrienoate may therefore affect metabolism in diverse ways--20:3n-3, which is retroconverted to 18:3n-3, may provide substrate for 20:5n-3 and 22:6n-3 syntheses, whereas intact 20:3n-3 may be incorporated into the CL pool. Acyl modifications of CL are known to affect the activity of key innermitochondrial enzymes, such as cytochrome c oxidase.