Effects of n-3 Fatty Acids Supplementation on Plasma Phospholipids Fatty Acid Composition in Patients with Obstructive Jaundice- a Pilot Study

Nutritional and immunological status of patients with obstructive jaundice is usually severely altered, with high mortality rates. The n-3 polyunsaturate fatty acids (PUFA), particularly eicosapentaenoic acid (EPA, 20:5 n-3), posess potent immunomodulatory activities. Thus, our aim was to compare the plasma phospholipid fatty acid (FA) composition of these patients with healthy subjects, as well as before and after 7 days preoperative supplementation with high doses of EPA (0.9 g per day) and docosahexaenoic acid (DHA, 22:6 n-3, 0.6 g per day). We found impaired FA status in obstructive jaundice patients, especially EPA, DHA and PUFA, but significantly increased content of total n-3 FA, 22:5 n-3 FA and particularly EPA, which increased more than 3 fold, after 7 days supplementation. In addition, the n6/n3 ratio significantly decreased from 14.24 to 10.24, demonstrating severely improved plasma phospholipid profile in these patients after the intervention.     

Incorporation and clearance of omega-3 fatty acids in erythrocyte membranes and plasma phospholipids

BACKGROUND: The sum of eicosapentaenoic acid (EPA, 20:5 omega3) and docosahexaenoic acid (DHA, 22:6 omega3) in erythrocyte membranes, termed the omega-3 index, can indicate suboptimal intake of omega-3 fatty acids, a risk factor for cardiovascular disease (CVD). To study the effects of fatty acid supplementation, we investigated the rate of incorporation and clearance of these fatty acids in erythrocyte membranes and plasma after intake of supplements. METHODS: Twenty study participants received supplementation with either fish oil (1296 mg EPA + 864 mg DHA/day) or flaxseed oil (3510 mg alpha-linolenic acid + 900 mg linoleic acid/day) for 8 weeks. We obtained erythrocyte membrane and plasma samples at weeks 0, 4, 8, 10, 12, 14, 16, and 24 and extracted and analyzed fatty acids by gas chromatography. RESULTS: After 8 weeks of fish oil supplementation, erythrocyte membrane EPA and DHA increased 300% (P < 0.001) and 42% (P < 0.001), respectively. The mean erythrocyte omega-3 index reached a near optimal value of 7.8%, and remained relatively high until week 12. EPA and DHA showed greater increases and more rapid washout period decreases in plasma phospholipids than in erythrocyte membranes. Flaxseed oil supplementation increased erythrocyte membrane EPA to 133% (P < 0.05) and docosapentaenoic acid (DPA, 22:5 omega3) to 120% (P < 0.01) of baseline, but DHA was unchanged. In plasma phospholipids, EPA, DPA, and DHA showed a slight but statistically insignificant increase. CONCLUSIONS: Erythrocyte membrane EPA+DHA increases during relatively short intervals in response to supplementation at rates related to amount of supplementation. These results may be useful to establish appropriate dosage for omega-3 fatty acid supplementation.     

Dietary n-3 fatty acid effects on neutrophil lipid composition and mediator production. Influence of duration and dosage.

Healthy volunteers supplemented their usual Western diets with Promega fish oil supplement (eicosapentaenoic acid [EPA], 0.28 g; docosahexaenoic acid [DCHA], 0.12 g; other n-3 fatty acids 0.10 g per capsule) using three protocols. Initial experiments (protocol 1 and 2) investigated the kinetics of incorporation of n-3 fatty acids into serum and neutrophil lipids after 10 capsules/d of Promega. EPA was rapidly detected in both serum and neutrophil lipids; the arachidonic acid (AA) to EPA ratio in neutrophil phospholipids showed a maximal reduction of 49:1 to 8:1 within 1 wk of beginning supplementation. EPA was preferentially incorporated into phosphatidyl-ethanolamine and phosphatidylcholine but not phosphatidylinositol. Long-term supplementation for up to 7 wk did not influence the AA/EPA ratio or the distribution of EPA among neutrophil phospholipids in a manner that was not observed after the first week. Neutrophils produced similar quantities of platelet-activating factor and slightly lower quantities of leukotriene B4 during long-term supplementation when compared with presupplementation values. Experiments examining the influence of Promega dosage indicated that the AA/EPA ratio in neutrophil lipids decreased in a dose-dependent manner. Only when the dose was increased to 15 capsules/d was there a reduction in the AA/DCHA ratio in neutrophil lipids. The quantity of AA in neutrophil lipids remained relatively constant at all supplement doses. Taken together, the current study demonstrates the capacity of n-3 fatty acids provided with a Western diet to be rapidly incorporated into neutrophil lipids. However, dietary n-3 fatty acids appear not to significantly reduce arachidonate content within neutrophil phospholipids. Constant arachidonate levels may account for the lack of large reductions in the biosynthesis of lipid mediators by neutrophils after fish-oil supplementation.     

Dietary n-6 fatty acids inhibit the incorporation of dietary n-3 fatty acids in thrombocyte and serum phospholipids in humans: a controlled dietetic study

The effect of a high dietary intake of n-6 fatty acids (36 g daily) vs a low intake (4-6 g daily) on the incorporation of fatty acids from a dietary supplementation of n-3 fatty acids (6 g daily) was studied for 8 weeks in 15 healthy, normolipaemic volunteers. The importance of a high (43.6) vs a low (20.6) energy percentage from fat was also investigated in the participants on a low n-6 intake. Fatty acid analyses of serum and thrombocyte phospholipids showed a marked increase in docosahexaenoic acid (22:6 (n-3), DHA) and especially eicosapentaenoic acid (20:5 (n-3), EPA) in both the high and low n-6 groups after 14 days, but the changes were significantly greater in the low n-6 diet groups. Changes of the ratio between EPA and arachidonic acid (20:4 (n-6), AA) in phospholipids followed an identical pattern in serum and thrombocytes. This indicates that thrombocytes are influenced by the fatty acid composition in serum. The results showed that incorporation of n-3 fatty acids in phospholipids was reduced by a high intake of dietary n-6 fatty acids in the cells and lipid fractions studied. The observed effect of dietary n-6 fatty acids was independent of the energy percentage provided by dietary fat. In order to obtain an optimal effect of n-3 supplementation, the intake of linoleic acid has to be considered and kept at a low level. The serum content of cholesterol was unaffected, but the concentration of triacylglycerol was reduced during the supplementation period.     

Dietary fatty acids, serum lipids, platelet biochemistry and function

Dietary fatty acids of the n-6 mainly linoleic acid (LA) series, and of the n-3, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) series both reduce plasma cholesterol levels and platelet responses to aggregating agents. The potency of n-3 fatty acids, which are present in relatively high concentrations in fish oils, is at least one order of magnitude greater than that of LA. The effects of fish oils appear to be related to the incorporation of EPA into plasma lipoproteins and cell phospholipid pools, thus modulating metabolic processes within specific lipid pools. Inhibition of platelet function and modifications of the activity of other blood cells, such as leukocytes, is attributed to interference with the eicosanoid system. Competition of EPA with arachidonic acid (AA) for the oxygenases and/or generation of less active metabolites from this precursor are the major mechanisms of action. Feeding studies in experimental animals indicate that exogenously administered n-3 fatty acids undergo distribution among the major plasma lipid classes and platelet phospholipids quite different to that of endogenous AA. In addition, the generation of inositolphosphates by stimulated platelets is decreased by dietary n-3 fatty acids in a manner independent of the effects on the eicosanoid system. It appears that polyunsaturated fatty acids (PUFA) of the n-6 and n-3 series are differently handled in various lipid pools and that early steps of cell activation, in addition to the generation of eicosanoids, are affected by dietary fatty acids. This indicates that fatty acids modulate key steps in the regulation of cell function and biochemistry.(ABSTRACT TRUNCATED AT 250 WORDS)     

Omacor® (prescription omega-3-acid ethyl esters 90): From severe rhythm disorders to hypertriglyceridemia

Despite progress made in post-myocardial infarction (MI) revascularization and background therapy for the failing heart, the prevention of adverse cardiac remodeling associated with severe rhythm disorders remains an important drug target. Part of the remodeling can be counteracted by modulating the activity of ion channels and exchangers by omega-3 acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In the GISSI-Prevenzione and GISSI-HF trials, omega-3 fatty acids were administered as ethyl esters (Omacor® Solvay Pharmaceuticals) and not as triglycerides present in fish oil. Ethyl esters result in a sustained intestinal absorption of EPA and DHA and require various purification steps during production, thereby minimizing the content of environmental toxins. Also the rather high (38%) DHA content of Omacor® should not be ignored since in rats with low dose intake of omega-3 acids, DHA but not EPA inhibited ischemia-induced arrhythmias. In patients on multiple tablets, 840 mg EPA+DHA in one capsule is preferred to increase compliance. It is not justified to refer to Omacor® as “n-3 polyunsaturated fatty acid supplementation” or even “fish oil” and, based on controlled clinical trials, there is no evidence that fish oil could be a substitute of Omacor®. To avoid further confusion, guidelines should be precise and refer to the medication, eg, as in NICE guideline CG48: “Omega-3-acid ethyl esters treatment licensed for secondary prevention post-MI.” The anti-arrhythmogenic action of Omacor® should be seen in the context of implantable cardioverter-defibrillator trials (DINAMIT, IRIS) where non-sudden death was increased and total mortality unaltered. However, Omacor® administered in the GISSI-HF trial reduced the incidence of severe arrhythmic events and mortality. Also in the GISSI-Prevenzione trial, arrhythmic death and mortality were reduced. At higher dosages (daily, 3–4 g) Omacor® exhibits more pronounced cardiovascular benefits and, as a licensed indication, improves hypertriglyceridemia and related lipid parameters.     

Effects of fish oil fatty acids on plasma lipids and lipoproteins and oxidant-antioxidant imbalance in healthy subjects

The purpose of this study was to investigate the effect of eicosapentaenoic and docosahexaenoic acids on plasma lipids and lipoproteins, lipid peroxidation and antioxidant status in healthy humans. A total of 19 healthy volunteers consumed 6 g/day Maxepa® fish oil for 3 weeks (1.8 g n-3 fatty acids/day). At baseline and at day 21, we evaluated plasma lipoproteins, plasma and low-density lipoprotein fatty acids, lipid peroxidation markers (malondialdehyde concentration, low-density lipoprotein peroxidation in vitro), and the content of a number of antioxidants (reduced and oxidized glutathione in whole blood, plasma and erythrocyte glutathione peroxidases, plasma vitamin E and beta carotene). Plasma concentrations of total cholesterol, triglycerides, phospholipids, low-density lipoprotein cholesterol and low-density lipoprotein size did not differ significantly after 3 weeks of supplementation. Adding the fish oil to the diet increased the concentration of n-3 very-long-chain polyunsaturated fatty acids and decreased the concentration of n-6 fatty acid and oleic acid in plasma and low-density lipoprotein. Eicosapentaenoic and docosahexaenoic acid supplementation caused elevated values of the high-density lipoprotein cholesterol due to an increment of the high-density lipoprotein 2 fraction and reduced low-density lipoprotein peroxidation rate in vitro. However, we observed an imbalance between oxidizable substrates and antioxidants with an increased lipid peroxidation, whereas the content of reduced glutathione and beta carotene decreased without any variation in vitamin E. Association of antioxidants with n-3 PUFA could prevent lipid peroxidation and enhance the antiatherogenic effects of n-3 polyunsaturated fatty acids.     

Effects of fish oil fatty acids on plasma lipids and lipoproteins and oxidant-antioxidant imbalance in healthy subjects.

The purpose of this study was to investigate the effect of eicosapentaenoic and docosahexaenoic acids on plasma lipids and lipoproteins, lipid peroxidation and antioxidant status in healthy humans. A total of 19 healthy volunteers consumed 6 g/day Maxepa fish oil for 3 weeks (1.8 g n-3 fatty acids/day). At baseline and at day 21, we evaluated plasma lipoproteins, plasma and low-density lipoprotein fatty acids, lipid peroxidation markers (malondialdehyde concentration, low-density lipoprotein peroxidation in vitro), and the content of a number of antioxidants (reduced and oxidized glutathione in whole blood, plasma and erythrocyte glutathione peroxidases, plasma vitamin E and beta carotene). Plasma concentrations of total cholesterol, triglycerides, phospholipids, low-density lipoprotein cholesterol and low-density lipoprotein size did not differ significantly after 3 weeks of supplementation. Adding the fish oil to the diet increased the concentration of n-3 very-long-chain polyunsaturated fatty acids and decreased the concentration of n-6 fatty acid and oleic acid in plasma and low-density lipoprotein. Eicosapentaenoic and docosahexaenoic acid supplementation caused elevated values of the high-density lipoprotein cholesterol due to an increment of the high-density lipoprotein 2 fraction and reduced low-density lipoprotein peroxidation rate in vitro. However, we observed an imbalance between oxidizable substrates and antioxidants with an increased lipid peroxidation, whereas the content of reduced glutathione and beta carotene decreased without any variation in vitamin E. Association of antioxidants with n-3 PUFA could prevent lipid peroxidation and enhance the antiatherogenic effects of n-3 polyunsaturated fatty acids.     

Encapsulated fish oil enriched in alpha-tocopherol alters plasma phospholipid and mononuclear cell fatty acid compositions but not mononuclear cell functions

BACKGROUND: Several studies have reported that dietary fish oil (FO) supplementation alters cytokine production and other functional activities of peripheral blood mononuclear cells (PBMC). However, few of these studies have been placebo controlled and few have related the functional changes to alterations in PBMC fatty acid composition PATIENTS AND METHODS: Healthy subjects supplemented their diets with 9 g day-1 of encapsulated placebo oil (3 : 1 mix of coconut and soybean oils), olive oil (OO), safflower oil (SO), evening primrose oil (EPO) or FO [providing 2.1 g eicosapentaenoic acid (EPA) plus 1.1 g docosahexaenoic acid (DHA) per day] for 12 weeks; the capsules also provided 205 mg alpha-tocopherol per day. Blood was sampled at 4-weekly intervals and plasma and PBMC prepared. Plasma phospholipid and PBMC fatty acid composition, plasma alpha-tocopherol and thiobarbituric acid-reactive substance concentrations, plasma total antioxidant capacity, the proportions of different PBMC subsets, the proportions of PBMC expressing the adhesion molecules CD2, CD11b and CD54, and PBMC functions (lymphocyte proliferation, natural killer cell activity, cytokine production) were measured. All measurements were repeated after a 'washout' period of 8 weeks. RESULTS: The placebo, OO and SO capsules had no effect on plasma phospholipid or PBMC fatty acid composition. The proportion of dihomo-gamma-linolenic acid in plasma phospholipids was elevated in subjects taking EPO and was decreased in subjects taking FO. There was no appearance of gamma-linolenic acid in the plasma phospholipids or PBMC in subjects taking EPO. There was a marked increase in the proportion of EPA in the plasma phospholipids (10-fold) and PBMC (four-fold) of subjects taking FO supplements; this increase was maximal after 4 weeks of supplementation. There was an increase in the proportion of DHA in plasma phospholipids and PBMC, and an approximately 20% decrease in the proportion of arachidonic acid in plasma phospholipids and PBMC, during FO supplementation. Plasma concentrations of alpha-tocopherol were significantly elevated during supplementation in all subjects and returned to baseline values after the washout period. There were no effects of supplementation with any of the capsules on total plasma antioxidant activity or plasma thiobarbituric acid-reactive substances or on the proportion of different PBMC subsets, on the proportion of PBMC expressing adhesion molecules, on natural killer cell activity, on the proliferation of mitogen-stimulated whole blood cultures or PBMC, or on the ex vivo production of a range of cytokines by whole blood cultures or PBMC cultures stimulated by either concanavalin A or lipopolysaccharide. CONCLUSION: Supplementation of the diet with 3.2 g EPA plus DHA per day markedly alters plasma phospholipid and PBMC fatty acid compositions. The lack of effect of FO upon PBMC functions may relate to the level of alpha-tocopherol included in the supplements.     

Omega-3 fatty acids for cardioprotection

The most compelling evidence for the cardiovascular benefit provided by omega-3 fatty acids comes from 3 large controlled trials of 32,000 participants randomized to receive omega-3 fatty acid supplements containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) or to act as controls. These trials showed reductions in cardiovascular events of 19% to 45%. These findings suggest that intake of omega-3 fatty acids, whether from dietary sources or fish oil supplements, should be increased, especially in those with or at risk for coronary artery disease. Patients should consume both DHA and EPA. The target DHA and EPA consumption levels are about 1 g/d for those with known coronary artery disease and at least 500 mg/d for those without disease. Patients with hypertriglyceridemia benefit from treatment with 3 to 4 g/d of DHA and EPA, a dosage that lowers triglyceride levels by 20% to 50%. Although 2 meals of oily fish per week can provide 400 to 500 mg/d of DHA and EPA, secondary prevention patients and those with hypertriglyceridemia must use fish oil supplements if they are to reach 1 g/d and 3 to 4 g/d of DHA and EPA, respectively. Combination therapy with omega-3 fatty acids and a statin is a safe and effective way to improve lipid levels and cardiovascular prognosis beyond the benefits provided by statin therapy alone. Blood DHA and EPA levels could one day be used to identify patients with deficient levels and to individualize therapeutic recommendations.     

Distal procto-colitis and n-3 polyunsaturated fatty acids: the mechanism(s) of natural cytotoxicity inhibition

BACKGROUND: Altered natural killer (NK) and lymphokine-activated killer (LAK) cell activities have been reported with ulcerative colitis (UC). Previously, we have shown that in patients with UC, the n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), specifically inhibit natural cytotoxicity with clinical improvement in disease activity. The aim of this study therefore was to evaluate the possible mechanism(s) involved in this inhibition, and in particular the alteration of production of interleukin 2 (IL2) and the arachidonic acid metabolite leukotriene B4 (LTB4), both known to modulate NK cell activity. MATERIALS AND METHODS: Each patient with procto-colitis received either fish oil extract (EPA 3.2 g, DHA 2.4 g; n = 9) or placebo (n = 9) daily for 6 months. Monthly assessment included disease activity using clinical and sigmoidoscopic scores. Peripheral blood mononuclear (PBMN) cells were isolated and NK cell cytotoxic activity in vitro was measured. Monthly serum samples were analysed for LTB4, IL2 and soluble IL2 receptors (sIL2R). RESULTS: The n-3 PUFAs group had significantly reduced NK cell activity, compared with the placebo group (P < 0.05, Mann-Whitney U-test). In the n-3 PUFA group, incubation of PBMN cells for 72 h with recombinant interleukin 2 (rIL2) reversed the NK inhibition. In patients with active proctocolitis, serum levels of LTB4 correlated positively with NK cell cytotoxicity (r = 0.873, P < 0.05, Kendall's correlation coefficient). After six months of n-3 PUFAs supplementation, serum levels of LTB4 were undetectable with concurrent significant reduction in NK cell cytotoxic activity. The latter was associated with significant reduction of serum IL2 and sIL2R levels (P < 0.05). CONCLUSION: This study has demonstrated both evidence of suppression of immune reactivity and concurrent reduction in disease activity in patients with proctocolitis receiving n-3 PUFAs supplementation. This may have important implications for therapy in patients with UC.     

Hypercholesterolaemia alters the responses of the plasma lipid profile and inflammatory markers to supplementation of the diet with n-3 polyunsaturated fatty acids from fish oil

BACKGROUND: The influence of supplementing the diet with long-chain n-3 polyunsaturated fatty acids (PUFA) from fish oil on plasma lipids and lipid peroxides and the production of pro-inflammatory mediators in normolipidaemic and hypercholesterolaemic rats were studied. MATERIALS AND METHODS: Rats were divided into four groups and fed one of the following diets: a control diet (containing 4% corn oil); an n-3 PUFA diet [containing 4% eicospentaenoic (EPA) + docosahexaenoic (DHA)]; a hypercholesterolaemic diet (HCH); or a HCH + n-3 PUFA diet over a 4-week period. Plasma lipids, lipid peroxides, cytokines [tumour necrosis factor (TNF)alpha, interleukin (IL)-6, interferon (IFN)gamma] and mRNA for hepatic nuclear factor-4alpha (HNF4alpha) were determined. RESULTS: Plasma triglyceride (TG), but not cholesterol, levels were decreased by the n-3 PUFA as compared with the control diet (P < 0.001), but the addition of n-3 PUFA to the HCH diet decreased both the TG (P < 0.01) and cholesterol (P < 0.05) concentrations. Plasma lipid peroxides and expression HNF4alpha mRNA were increased by n-3 PUFA in the normolipidaemic (P < 0.05), but not in the hyperlipidaemic rats. Compared with the control diet group, plasma concentrations of TNFalpha and IL-6 were increased in the n-3 PUFA (P < 0.05) and HCH diet (P < 0.05, P < 0.01, respectively) groups, but not in animals given the HCH + n-3 PUFA diet, whereas IFNgamma levels were increased in hypercholesterolaemia (P < 0.05), but were unaffected by n-3 PUFA. CONCLUSION: These results demonstrate that the major effect of fish oil n-3 PUFA is to lower the TG levels in both normo- and hyperlipidaemia. Furthermore, in the hypercholesterolaemic state, fish oil n-3 PUFA induces additional beneficial changes in the immune and peroxidation responses.     

n-3 fatty acid-enriched parenteral nutrition regimens in elective surgical and ICU patients: a meta-analysis

Introduction

Previous studies and a meta-analysis in surgical patients indicate that supplementing parenteral nutrition regimens with n-3 polyunsaturated fatty acids (PUFAs), in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is associated with improved laboratory and clinical outcomes in the setting of hyper-inflammatory conditions. Refined or synthetic fish oils are commonly used as a source of EPA and DHA. The objective of the present meta-analysis was to evaluate n-3 PUFA-enriched parenteral nutrition regimens in elective surgical and intensive care unit (ICU) patients.

Methods

Medline was searched for randomized controlled trials comparing n-3 PUFA-enriched lipid emulsions with standard non-enriched lipid emulsions (i.e. soybean oil, MCT/LCT or olive/soybean oil emulsions) in surgical and ICU patients receiving parenteral nutrition. Extracted data were pooled by means of both random and fixed effects models, and subgroup analyses were carried forward to compare findings in ICU versus non-ICU patients.

Results

A total of 23 studies (n = 1502 patients: n = 762 admitted to the ICU) were included. No statistically significant difference in mortality rate was found between patients receiving n-3 PUFA-enriched lipid emulsions and those receiving standard lipid emulsions (RR= 0.89; 0.59, 1.33), possibly reflecting a relatively low underlying mortality risk. However, n-3 PUFA-enriched emulsions are associated with a statistically and clinically significant reduction in the infection rate (RR =0.61; 0.45, 0.84) and the lengths of stay, both in the ICU (-1.92; -3.27, -0.58) and in hospital overall (-3.29; -5.13, -1.45). Other beneficial effects included reduced markers of inflammation, improved lung gas exchange, liver function, antioxidant status and fatty acid composition of plasma phospholipids, and a trend towards less impairment of kidney function.

Conclusions

These results confirm and extend previous findings, indicating that n-3 PUFAs-enriched parenteral nutrition regimens are safe and effective in reducing the infection rate and hospital/ICU stay in surgical and ICU patients.     

N-3 fatty acids stimulate intracellular degradation of apoprotein B in rat hepatocytes.

When rat hepatocytes were incubated with albumin complexed to the n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), rather than to oleic acid (OA), the secretion of newly synthesized apoprotein B100 (apoB100) or B48 (apoB48) was reduced, despite stimulation of cellular triglyceride synthesis by all three fatty acids. When pulse-chase studies of apoB synthesis and secretion were performed in the presence of OA, EPA, or DHA, there were no significant changes in the initial synthetic rates of either apoB species. However, during the chase period, the total recovery of labeled apoB100 and apoB48 from the cell and medium was less in the n-3 fatty acid groups, so that by 150 min, approximately half as much labeled apoB was recovered as in the OA group. Overall, the decreased accumulation in medium of labeled apoB in the presence of EPA and DHA could be quantitatively accounted for by increased degradation of intracellular apoB. Thus, in the primary hepatocyte, apoB degradation is not constitutive, but can be regulated by n-3 fatty acids.     

DHA concentration of red blood cells is inversely associated with markers of lipid peroxidation in men taking DHA supplement

An increase in the proportion of fatty acids with higher numbers of double bonds is believed to increase lipid peroxidation, which augments the risk for many chronic diseases. (n-3) Polyunsaturated fatty acids provide various health benefits, but there is a concern that they might increase lipid peroxidation. We examined the effects of docosahexaenoic acid [22:6 (n-3)] supplementation on lipid peroxidation markers in plasma and red blood cells (RBC) and their associations with red blood cell and plasma fatty acids. Hypertriglyceridemic men (n = 17 per group) aged 39–66 years participated in a double-blind, randomized, placebo-controlled, parallel study. They received no supplements for the first 8 days and then received 7.5 g/day docosahexaenoic acid oil (3 g/day docosahexaenoic acid) or olive oil (placebo) for 90 days. Fasting blood samples were collected 0, 45, and 91 days after supplementation. Docosahexaenoic acid supplementation did not change plasma or RBC concentrations of lipid peroxidation markers (total hydroxyoctadecadienoic acid, total hydroxyeicosatetraenoic acid, total 8-isoprostaglandin F_2α, 7α-hydroxycholesterol, 7β-hydroxycholesterol) when pre- and post-supplement values were compared. However, the post-supplement docosahexaenoic acid (DHA) concentration was inversely associated with RBC concentrations of ZE-HODE, EE-HODE, t-HODE, and total 8-isoprostaglandin F_2α, (p<0.05). RBC concentration of hydroxycholesterol was also inversely associated with DHA but it did not attain significance (p = 0.07). Our results suggest that increased concentration of DHA in RBC lipids reduced lipid peroxidation. This may be another health benefit of DHA in addition to its many other health promoting effects.     

Supplementation with fish oil affects the association between very long-chain n-3 polyunsaturated fatty acids in serum non-esterified fatty acids and soluble vascular cell adhesion molecule-1

We have investigated the effect of fish oil supplementation on the association between serum non-esterified fatty acid (NEFA) pattern and atherosclerotic activity. We studied correlations between serum non-esterified very long-chain eicosapentaenoic (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) and biochemical markers of endothelial activation before and after 18-months intervention with fish oil supplementation. The fish oil supplementation consisted of 2.4 g of EPA and DHA per day, with corn oil as placebo. Elderly men ( n =171) with high risk for coronary heart disease were divided into four intervention groups in a factorial design: fish oil supplementation ( n =44), dietary intervention ( n =42), fish oil supplementation+dietary intervention ( n =47) or placebo ( n =38). The composition of fasting NEFA was analysed before and after intervention by GLC. Circulating endothelial markers were analysed by ELISA. A statistically significant positive correlation between the change in serum non-esterified DHA and soluble vascular cell adhesion molecule-1 (sVCAM-1) was found in the pooled group that received fish oil supplementation ( n =91; Spearman's correlation coefficient r =0.24, P =0.02). No such correlation was found in the pooled group without fish oil supplementation ( n =80). Furthermore, there was a significant negative correlation between the change in serum non-esterified EPA and the relative change in sVCAM-1 in the group that did not receive fish oil supplementation ( r =-0.34, P =0.002). No such correlation was found in the group with fish oil supplementation. We conclude that large increase in serum non-esterified EPA and DHA, which can only be attained by supplementation, might increase inflammation in vascular endothelium. A moderate dietary increase in fish oil intake may, however, have an effect on decreasing inflammatory markers.     

Application of high EPA-producing Mortierella alpina in laying hen feed for egg DHA accumulation

Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA, C20:5) and docosahexaenoic acid (DHA, C22:6), are beneficial for human health. In this study, we selected a high EPA content (30% in total fatty acids) strain of Mortierella alpina CCFM 698 that overexpressed an ω-3 fatty acid desaturase from Phytophthora parasitica, and investigated the cell growth and lipid accumulation of this strain in a 65 L airlift fermenter with glucose batch feeding. The maximum cell dry weight was 28.7 g L⁻¹ and the highest total fatty acid content was 33.0% (w/w) in cell dry weight. The highest EPA yield was 1.8 g L⁻¹. Both low and high dose supplementation of this strain into the feed of laying hens increased DHA accumulation in the yolk. The highest DHA content of 7.61 mg g⁻¹ yolk was achieved in Fengda-1 laying hens with 4% supplementation and the DHA production per egg was 118.46 mg. However, Hy-Line Brown laying hens displayed a higher DHA production per egg and the value was 131.50, 131.72, 131.95 mg with 1.5%, 2%, 4% supplementation, respectively. The lowest ratio of ω-6/ω-3 PUFAs (3.53) was obtained in Hy-Line Brown laying hens with 4% supplementation. These results suggest that M. alpina CCFM 698 can be used as an alternative source of ω-3 PUFAs in feed to produce nutritious eggs with high DHA content.

A high EPA-producing M. alpina was fermented and added to laying hen feed for egg yolk DHA accumulation.     

Eating Fish and Risk of Type 2 Diabetes: A population-based, prospective follow-up study

OBJECTIVE

To investigate the relation between total fish, type of fish (lean and fatty), and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intake and risk of type 2 diabetes in a population-based cohort.

RESEARCH DESIGN AND METHODS

The analysis included 4,472 Dutch participants aged ≥55 years without diabetes at baseline. Dietary intake was assessed with a semiquantitative food frequency questionnaire. Hazard ratios (relative risk [RR]) with 95% CIs were used to examine risk associations adjusted for age, sex, lifestyle, and nutritional factors.

RESULTS

After 15 years of follow-up, 463 participants developed type 2 diabetes. Median fish intake, mainly lean fish (81%), was 10 g/day. Total fish intake was associated positively with risk of type 2 diabetes; the RR was 1.32 (95% CI 1.02–1.70) in the highest total fish group (≥28 g/day) compared with that for non–fish eaters (P_trend = 0.04). Correspondingly, lean fish intake tended to be associated positively with type 2 diabetes (RR highest group ]≥23 g/day] 1.30 [95% CI 1.01–1.68]; P_trend = 0.06), but fatty fish was not. No association was observed between EPA and DHA intake and type 2 diabetes (RR highest group [≥149.4 mg/day] 1.22 [0.97–1.53]). With additional adjustment for intake of selenium, cholesterol, and vitamin D, this RR decreased to 1.05 (0.80–1.38; P_trend = 0.77).

CONCLUSIONS

The findings do not support a beneficial effect of total fish, type of fish, or EPA and DHA intake on the risk of type 2 diabetes. Alternatively, other dietary components, such as selenium, and unmeasured contaminants present in fish might explain our results.Potential benefits of the intake of fish on the development of type 2 diabetes could be attributed to its high content of dietary n-3 polyunsaturated fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Higher EPA and DHA quantities in the phospholipid cell membranes could increase insulin sensitivity (1). EPA and DHA supplementation increased insulin sensitivity in animal models and in some human studies (2). Results of prospective studies on intake of long-chain n-3 fatty acids and type 2 diabetes risk, however, did not show a relation (3,4). Apart from EPA and DHA, other components within fish, such as selenium and vitamin D, could also be related to type 2 diabetes. Vitamin D could be negatively and selenium could be positively associated with type 2 diabetes (5,6).Results of studies that investigated the association between fish intake and type 2 diabetes risk are inconclusive. An ecological study reported that high fish intake may reduce the risk of type 2 diabetes in populations with a high prevalence of obesity (7). Cross-sectional studies reported inverse (8,9), no (10,11), or positive (12) associations between habitual fish intake and glycemic status. Prospective evidence suggested that fish intake is either inversely (13,14) or not associated (15) with the risk of type 2 diabetes.Taken together, the effects of fish intake and EPA and DHA intake on the development of type 2 diabetes are ambiguous. Furthermore, studies conducted in this field did not report associations between different types of fish and type 2 diabetes risk. EPA and DHA are present mainly in fatty fish, which might indicate that it is also important to pay attention to the type of fish that is eaten instead of total fish intake alone.Therefore, we investigated the relation between the intake of total fish, type of fish (lean or fatty), and EPA and DHA and type 2 diabetes risk in a population of men and women aged ≥55 years. We hypothesized that fish intake and especially fatty fish intake is related inversely to the risk of type 2 diabetes.     

The ratio of eicosapentaenoic acid to docosahexaenoic acid as a modulator for the cardio-metabolic effects of omega-3 supplements: A meta-regression of randomized clinical trials

BackgroundA large number of studies have demonstrated the effects of omega- 3 supplements containing mixtures of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), known to favorably affect many modifiable risk factors of coronary heart disease (CHD). These studies have used diverse ratios and doses of EPA and DHA. However, it is not known whether the ratio of EPA to DHA in omega-3 supplements affect their efficacy as modulators for cardiovascular risk factors. This meta-regression aimed to investigate the effect of different ratios of EPA to DHA on risk factors associated with CHD including lipid profile, blood pressure, heart rate, and inflammation.MethodA regression analysis was carried out on 92 clinical trials with acceptable quality (Jadad score ≥ 3) that were previously identified from two databases (PubMed and Cochrane Library).ResultsData from studies that met the inclusion criteria for this analysis showed that the ratio of EPA to DHA was not associated with lipid profile, diastolic blood pressure, or heart rate. With all studies, the ratio of EPA to DHA was associated with C-reactive protein (CRP) (β = -1.3121 (95 % CI: -1.6610 to -0.9543), that is, the higher the EPA to DHA ratio, the greater the reduction. Using only studies that supplied EPA and DHA in the range of 2 g–6 g, the ratio of EPA to DHA was also associated with CRP (β = -2.10429 and 95 % CI: -3.89963 to -0.30895); that is, an even more pronounced reduction in CRP with a higher EPA to DHA ratio. Systolic blood pressure was only associated with an increasing EPA to DHA ratio in the 2 g–6 g range (β = 5.47129 and 95 % CI: 0.40677–10.53580), that is, a higher EPA to DHA ratio within this dose range, the greater the increase in SBP.ConclusionCurrent data suggest that the EPA to DHA ratio only correlates to the modulation of CRP by omega-3 supplementation of EPA and DHA, and SBP in studies that supplemented EPA and DHA in the range of 2 g–6 g, shedding light on potential differential effects of EPA vs. DHA on inflammation and systolic blood pressure.