Effects of dietary fish oil supplementation on polymorphonuclear leukocyte inflammatory potential

Dietary omega-3 fatty acid intake impacts peripheral blood DNA methylation -anti-inflammatory effects and individual variability in a pilot study

Omega-3 or n-3 polyunsaturated fatty acids (PUFAs) are widely studied for health benefits that may relate to anti-inflammatory activity. However, mechanisms mediating an anti-inflammatory response to n-3 PUFA intake are not fully understood. Of interest is the emerging role of fatty acids to impact DNA methylation (DNAm) and thereby modulate mediating inflammatory processes. In this pilot study, we investigated the impact of n-3 PUFA intake on DNAm in inflammation-related signaling pathways in peripheral blood mononuclear cells (PBMCs) of women at high risk of breast cancer. PBMCs of women at high risk of breast cancer (n=10) were obtained at baseline and after 6 months of n-3 PUFA (5 g/d EPA+DHA dose arm) intake in a previously reported dose finding trial. DNA methylation of PBMCs was assayed by reduced representation bisulfite sequencing (RRBS) to obtain genome-wide methylation profiles at the single nucleotide level. We examined the impact of n-3 PUFA on genome-wide DNAm and focused upon a set of candidate genes associated with inflammation signaling pathways and breast cancer. We identified 24,842 differentially methylated CpGs (DMCs) in gene promoters of 5507 genes showing significant enrichment for hypermethylation in both the candidate gene and genome-wide analyses. Pathway analysis identified significantly hypermethylated signaling networks after n-3 PUFA treatment, such as the Toll-like Receptor inflammatory pathway. The DNAm pattern in individuals and the response to n-3 PUFA intake are heterogeneous. PBMC DNAm profiling suggests a mechanism whereby n-3 PUFAs may impact inflammatory cascades associated with disease processes including carcinogenesis.

Effects of Flaxseed Oil on Serum Lipids and Atherosclerosis in Hypercholesterolemic Rabbits

Objective: Flaxseed oil has very high content of ox-linolenic acid (C18:3n-3, omega-3 [n-3] fatty acid). Based on the usefulness of n-3 fatty acid in fish oil against cardiovascular diseases, flaxseed oil is marketed as a health food. The n-3 fatty acid in flaxseed oil is different than that of fish oil. Indirect evidence suggests that the omega-3 fatty acid in flaxseed oil is not effective in lowering serum lipids and hypercholesterolemic atherosclerosis. The effects of flaxseed oil on serum lipids and hypercholesterolemic atherosclerosis are not known. An investigation, therefore, was made of flaxseed oil on high-cholesterol diet-induced atherosclerosis, serum lipids (triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, risk ratio of total cholesterol to high-density lipoprotein cholesterol), serum and aortic malondialdehyde, an index of levels of reactive oxygen species, aortic chemiluminescence (a measure of antioxidant reserve), and reactive oxygen species-producing activity of white blood cell chemiluminescence in rabbits.

Methods: The rabbits were assigned to four groups: Group I, regular diet (control); Group II, 5% flaxseed oil in regular diet; Group III, 0.5% cholesterol diet; Group IV, diet containing 0.5% cholesterol and 5% flaxseed oil. Blood samples were collected before and after 4 and 8 weeks of experimental diets for measurement of serum lipids, serum malondialdehyde, and white blood cell chemiluminescence. At the end of 8 weeks of the experimental diet, aortas were removed for measurement of atherosclerotic plaques, aortic malondialdehyde, and antioxidant reserve.

Results: Serum total cholesterol, triglycerides, and low-density and high-density lipoprotein cholesterol, and risk ratio of total cholesterol to high-density lipoprotein cholesterol, were elevated to a similar extent in Groups III and IV compared to Groups I and II. The extent of atherosclerosis in Groups III and IV was similar (56.74% ± 11.14% vs 58.01% ± 10.95%). Groups III and IV both had similar increases in serum and aortic malondialdehyde and antioxidant reserve. Reactive oxygen species-producing activity of white blood cells increased in Group III, and flaxseed oil prevented the cholesterol-induced increase in white blood cell chemiluminescence in Group IV.

Conclusion: These results suggest that flaxseed oil does not produce an alteration in serum lipids or in the extent of hypercholesterolemic atherosclerosis; however, it decreases white blood cell chemiluminescence. The ineffectiveness of flaxseed oil was associated with its ineffectiveness in altering the levels of oxidative stress.

Food, nutrients and nutraceuticals affecting the course of inflammatory bowel disease

Inflammatory bowel diseases (ulcerative colitis; Crohn's disease) are debilitating relapsing inflammatory disorders affecting the gastrointestinal tract, with deleterious effect on quality of life, and increasing incidence and prevalence. Mucosal inflammation, due to altered microbiota, increased intestinal permeability and immune system dysfunction underlies the symptoms and may be caused in susceptible individuals by different factors (or a combination of them), including dietary habits and components. In this review we describe the influence of the Western diet, obesity, and different nutraceuticals/functional foods (bioactive peptides, phytochemicals, omega 3-polyunsaturated fatty acids, vitamin D, probiotics and prebiotics) on the course of IBD, and provide some hints that could be useful for nutritional guidance. Hopefully, research will soon offer enough reliable data to slow down the spread of the disease and to make diet a cornerstone in IBD therapy.

Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn's disease

BACKGROUND

The anti-inflammatory effects of n-3 (omega-3 fatty acids, fish oil) have been suggested to be beneficial in chronic inflammatory disorders such as inflammatory bowel disease. This review is an update of a previously published Cochrane review.

OBJECTIVES

To systematically review the efficacy and safety of n-3 for maintenance of remission in Crohn's disease (CD).

SEARCH METHODS

The following databases were searched from inception to November 2013 without language restriction: CENTRAL, MEDLINE, EMBASE, HealthSTAR, PubMed, and ACP journal club.

SELECTION CRITERIA

Randomized placebo-controlled trials (RCT) of n-3 for maintenance of remission in CD were included. Studies must have enrolled patients of any age group, who were in remission at the time of recruitment, and were followed for at least six months. The intervention must have been fish oil or n-3 given in pre-defined dosage. Co-interventions were allowed only if they were balanced between the study groups.

DATA COLLECTION AND ANALYSIS

The primary outcome was the relapse rate and secondary outcomes included change in disease activity scores, time to first relapse and adverse events. Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality using the Cochrane risk of bias tool. The overall quality of the evidence supporting the primary and selected secondary outcomes was reassessed for the current update using the GRADE system. We used the RevMan software for analyses. We calculated the risk ratio (RR) and corresponding 95% confidence interval (CI) for dichotomous outcomes and the hazard ratio and 95% CI for time-to-event outcomes. Random-effects or fixed-effect models were used according to degree of heterogeneity and sensitivity analyses were performed in an attempt to explore possible sources of heterogeneity.

MAIN RESULTS

Six studies with a total of 1039 patients were eligible for inclusion. The two largest studies were rated as low risk of bias for all assessed items. Four studies were rated as unclear risk of bias for randomization and allocation concealment. Two studies were rated as high risk of bias for incomplete outcome data and selective reporting. There was a marginal significant benefit of n-3 therapy for maintenance of remission. Thirty-nine per cent of patients in the n-3 group relapsed at 12 months compared to 47% of placebo patients (6 studies, 1039 patients; RR 0.77, 95% CI 0.61 to 0.98). A GRADE analysis rated the overall quality of the evidence for the primary outcome (i.e. relapse) as very low due to unexplained heterogeneity (I2 = 58%), publication bias, and a high or unknown risk of bias in four studies in the pooled analysis. When two large studies at low risk of bias were considered the benefit was no longer statistically significant. Thirty-seven per cent of patients in the n-3 group relapsed at 12 months compared to 42% of placebo patients (2 studies, 738 patients; RR 0.88, 95% CI 0.74 to 1.05). No significant heterogeneity was identified for this pooled analysis ( I2 = 0%). A GRADE analysis indicated that the overall quality of the evidence supporting this outcome was moderate due to sparse data (294 events). No serious adverse events were recorded in any of the studies but in a pooled analyses there was a significantly higher rate of diarrhea (4 studies, 862 patients; RR 1.36 95% CI 1.01 to 1.84) and upper gastrointestinal tract symptoms (5 studies, 999 patients; RR 1.65, 95% CI 1.25 to 2.18) in the n-3 treatment group.

AUTHORS' CONCLUSIONS

Evidence from two large high quality studies suggests that omega 3 fatty acids are probably ineffective for maintenance of remission in CD. Omega 3 fatty acids appear to be safe although they may cause diarrhea and upper gastrointestinal tract symptoms.

Effects of eye drops containing a mixture of omega-3 essential fatty acids and hyaluronic acid on the ocular surface in desiccating stress-induced murine dry eye

PURPOSE

To investigate the efficacy of the topical application of omega-3 essential fatty acids (EFAs) and hyaluronic acid (HA) mixtures in a mouse model of experimental dry eye (EDE).

METHODS

Eye drops consisting of 0.1% HA, 0.02%, or 0.2% omega-3 EFAs alone and mixture of 0.02%, or 0.2% omega-3 EFAs and 0.1% HA were applied in desiccating stress-induced murine dry eye. Corneal irregularity scores and fluorescein staining scores were measured 5 and 10 days after treatment. Levels of interleukin (IL)-1β, -17, and interferon gamma-induced protein (IP)-10 were measured in the conjunctiva at 10 days using a multiplex immunobead assay. The concentrations of hexanoyl-lys (HEL) and 4-hydroxynonenal (4-HNE) in conjunctiva tissue were measured with enzyme-linked immunosorbent assays.

RESULTS

Mice treated with the mixture containing 0.2% omega-3 EFAs showed a significant improvement in corneal irregularity scores and corneal fluorescein staining scores compared with EDE, HA, 0.02% or 0.2% omega-3 EFAs alone, and 0.02% omega-3 EFAs mixture-treated mice. A significant decrease in the levels of IL-1β, -17, and IP-10 were observed in the 0.2% EFAs mixture-treated group, compared with the other groups. In the mice treated with the mixture containing 0.2% omega-3 EFAs, the concentration of 4-HNE was also lower than the other groups. Although 0.2% omega-3 EFAs alone group also had a significant improvement in corneal irregularity scores and IL-17, IL-10, and 4 HNE levels compared with the other groups, the efficacy was lower than 0.2% omega-3 mixture group.

CONCLUSIONS

Topically applied eye drops containing a mixture of omega-3 EFAs and HA could improve corneal irregularity and corneal epithelial barrier disruption, and decrease inflammatory cytokines and oxidative stress markers on the ocular surface. Topical omega-3 EFAs and HA mixture may have a greater therapeutic effect on clinical signs and inflammation of dry eye compared with HA artificial tears.

Plasma phospholipid fatty acid and ex vivo neutrophil responses are differentially altered in dogs fed fish- and linseed-oil containing diets at the same n-6:n-3 fatty acid ratio

The effect of diets containing either 18-carbon n-3 fatty acids (FA) or 20/22-carbon n-3 FA on canine plasma and neutrophil membrane fatty acid composition, superoxide and leukotriene B₄ and B₅ production when fed at the same n-6:n-3 fatty acid ratio was investigated. Four groups of ten dogs each were fed a low fat basal diet supplemented with safflower oil (SFO), beef tallow (BTO), linseed oil (LSO), or Menhaden fish oil (MHO) for 28 days. Dietary fat provided 40.8% of energy and the n-6:n-3 of the diets were ~100:1, 9.7:1, 0.38:1, and 0.34:1 for the SFO, BTO, LSO and MHO groups, respectively. The MHO and LSO groups had increased incorporation of EPA and DPA in both the plasma and neutrophil membranes compared to the BTO and SFO groups. DHA was observed in the MHO but not in the LSO group. Neutrophils from the MHO diet fed dogs had less LTB₄ and greater LTB₅ than the other three groups. The LSO group also showed a reduction in LTB₄ and greater LTB₅ production compared to the SFO and BTO groups. Both LSO and MHO groups had lower superoxide production compared to the SFO and BTO groups. Diets containing 18 or 20/22 carbon n-3 FA fed at the same n-6:n-3 resulted in differential incorporation of long chain n-3 FA into neutrophil membranes. Thus, fatty acid type and chain length individually affect neutrophil membrane structure and function and these effects exist independent of dietary total n-6:total n-3 FA ratios.

Maintenance of remission in inflammatory bowel disease using omega-3 fatty acids (fish oil): a systematic review and meta-analyses

The objective was to systematically review the efficacy and safety of n-3 (omega-3 fatty acids, fish oil) for maintaining remission in Crohn's disease (CD) and ulcerative colitis (UC). Electronic databases were searched systematically for randomized controlled trials of n-3 for maintenance of remission in inflammatory bowel disease (IBD). Studies of patients of any age group who were in remission at the time of recruitment and were followed for at least 6 months were included. The primary outcome was relapse rate at the end of the follow-up period. Nine studies were eligible for inclusion; six studies of CD (n = 1039) and three of UC (n = 138). There was a statistically significant benefit for n-3 in CD (relative risk [RR] 0.77; 95% confidence interval [CI] 0.61-0.98); however, the studies were heterogeneous (I(2) = 58%). The absolute risk reduction was -0.14 (95% CI: -0.25 to -0.02). Opinions may vary on whether this is a clinically significant effect. Two well-done studies with a larger sample size reported no benefit. A sensitivity analysis excluding a small pediatric study resulted in the pooled RR being no longer statistically significant. A funnel plot analysis suggested publication bias for the smaller studies. For UC, there was no difference in the relapse rate between the n-3 and control groups (RR 1.02; 95% CI: 0.51-2.03). The pooled analysis showed a higher rate of diarrhea (RR 1.36; 95% CI: 1.01-1.84) and symptoms of the upper gastrointestinal tract (RR 1.96; 95% CI: 1.37-2.80) in the n-3 treatment group. There are insufficient data to recommend the use of omega 3 fatty acids for maintenance of remission in CD and UC.

Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn's disease

BACKGROUND

The anti-inflammatory effects of n-3 (omega-3 fatty acids, fish oil) have been suggested to be beneficial in chronic inflammatory disorders such as inflammatory bowel disease.

OBJECTIVES

To systematically review the efficacy and safety of n-3 for maintenance of remission in Crohn's disease (CD).

SEARCH STRATEGY

The following databases were searched from their inception without language restriction: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Healthstar, PubMed, and ACP journal club. Experts were contacted for unpublished data.

SELECTION CRITERIA

Randomized placebo-controlled trials (RCT) of n-3 for maintenance of remission in CD were included. Studies must have enrolled patients of any age group, who were in remission at the time of recruitment, and were followed for at least six months. The intervention must have been fish oil or n-3 given in pre-defined dosage. Co-interventions were allowed only if they were balanced between the study groups. The primary outcome was the relapse rate and secondary outcomes included change in disease activity scores, time to first relapse and adverse events.

DATA COLLECTION AND ANALYSIS

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality using Jadad's criteria. Meta-analyses were performed using RevMan 4.2 software weighted by the Mantel-Haenszel method. Random or fixed effect models were used according to degree of heterogeneity and subgroup analyses were performed in an attempt to explore possible sources of heterogeneity.

MAIN RESULTS

Six studies were eligible for inclusion. There was a marginal significant benefit of n-3 therapy for maintaining remission (RR 0.77 0.; 95%CI 0.61 to 0.98; P = 0.03). However, the studies were both clinically and statistically heterogeneous (P = 0.03, I(2) = 58%). Two large studies showed negative results. When considering the estimated rather than the observed 1-year relapse rate of these two studies, the benefit was no longer statistically significant (RR 0.59; 95% CI 0.34 to 1.03; P=0.06). A funnel plot suggested publication bias. No serious adverse events were recorded in any of the studies but in a pooled analyses there was a significantly higher rate of diarrhea (RR 1.36 95% CI 1.01 to 1.84) and symptoms of the upper gastrointestinal tract (RR 1.98 95% CI 1.38 to 2.85) in the n-3 treatment group.

AUTHORS' CONCLUSIONS

Omega 3 fatty acids are safe but probably ineffective for maintenance of remission in CD. The existing data do not support routine maintenance treatment of Crohn's disease with omega 3 fatty acids.

The effect of dietary fish oil-supplementation to healthy young men on oxidative burst measured by whole blood chemiluminescence

Dietary long-chain n-3 PUFA (n-3 LCPUFA) are thought to have immune-modulating effects, but the specific effects and mechanisms are not fully elucidated. The aim of this study was to determine whether dietary n-3 LCPUFA could affect ex vivo oxidative burst in healthy young men. The study had a randomised 2 x 2-factorial design in which subjects were randomly assigned to 8-week supplementation with capsules containing fish oil (about 2.9 g n-3 LCPUFA/d) or olive oil (control). Subjects were also randomly assigned to household use of oils and fat spreads with a high or a low 18:2n-6 content. At baseline and at the end of the intervention, the fatty acid composition of peripheral blood mononuclear cells (PBMC) was analysed by GLC and oxidative burst was studied in whole blood stimulated with zymosan using luminol-enhanced chemiluminescence. The PBMC content of n-3 LCPUFA was markedly increased by the fish oil-supplementation (P < 0.001, compared to the olive oil groups). No effect of the intervention was observed on neutrophil count, but one measure of the zymosan-induced oxidative burst was higher in the fish oil groups (P = 0.03) compared to the olive oil groups. The fat intervention did not in itself affect oxidative burst neither did it change the effect of the fish-oil intervention. The measures of oxidative burst at the end of the intervention period were found to be associated with the DHA content of PBMC (r 0.44, P = 0.016), suggesting a dose-response relationship. These results indicate that n-3 LCPUFA may have immuno-stimulating effects.

Omega 3 fatty acids (fish oil) for maintenance of remission in ulcerative colitis

BACKGROUND

Omega-3 fatty acids (n-3, fish oil) have been shown to have anti-inflammatory properties. Therefore, n-3 therapy may be beneficial in chronic inflammatory disorders such as ulcerative colitis.

OBJECTIVES

To systematically review the efficacy and safety of n-3 for maintaining remission in ulcerative colitis (UC).

SEARCH STRATEGY

The following databases were searched from their inception without language restriction: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Healthstar, PubMed, and ACP journal club. Experts were contacted for unpublished data.

SELECTION CRITERIA

Randomized placebo-controlled trials (RCT) of fish oil for maintenance of remission in UC were included. Studies must have enrolled patients (of any age group) who were in remission at the time of recruitment, and were followed for at least six months. The intervention must have been fish oil given in pre-defined dosage. Co-interventions were allowed only if they were balanced between the study groups. The primary outcome was relapse rate and the secondary outcome was frequency of adverse events. Other outcomes to assess efficacy were change in disease activity scores and time to first relapse.

DATA COLLECTION AND ANALYSIS

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality. Meta-analysis weighted by the Mantel-Haenszel method was performed using RevMan 4.2.8 software. Random or fixed effect models were used according to degree of heterogeneity and subgroup analyses were performed to explore heterogeneity. A sensitivity analysis was performed excluding a study of questionable quality .

MAIN RESULTS

The three studies that were included used different formulation and dosing of n-3 but none used enteric coated capsules. The pooled analysis showed a similar relapse rate in the n-3 treated patients and controls (RR 1.02; 95% CI 0.51 to 2.03; P = 0.96). Combining the studies resulted in virtually no statistical heterogeneity (P = 0.93, I(2) = 0%). Various subgroup and sensitivity analyses showed similar results. However, the total number of patients enrolled in these studies was small (n = 138). No significant adverse events were recorded in any of the studies and not enough data were available to pool the other secondary outcomes for meta-analysis.

AUTHORS' CONCLUSIONS

No evidence was found that supports the use of omega 3 fatty acids for maintenance of remission in UC. Further studies using enteric coated capsules may be justified.

Omega 3 fatty acids (fish oil) for maintenance of remission in Crohn's disease

BACKGROUND

The anti-inflammatory effects of n-3 (omega-3 fatty acids, fish oil) have been suggested to be beneficial in chronic inflammatory disorders such as inflammatory bowel disease.

OBJECTIVES

To systematically review the efficacy and safety of n-3 for maintaining remission in Crohn's disease (CD).

SEARCH STRATEGY

The following databases were searched from their inception without language restriction: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Healthstar, PubMed, and ACP journal club. Experts were contacted for unpublished data.

SELECTION CRITERIA

Randomized placebo-controlled trials (RCT) of n-3 for maintenance of remission in CD were included. Studies must have enrolled patients of any age group, who were in remission at the time of recruitment, and were followed for at least six months. The intervention must have been fish oil or n-3 given in pre-defined dosage. Co-interventions were allowed only if they were balanced between the study groups. The primary outcome was relapse rate and secondary outcomes were change in disease activity scores, time to first relapse and adverse events.

DATA COLLECTION AND ANALYSIS

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality using Jadad's criteria. Meta-analysis was performed using RevMan 4.2 software, weighted by the Mantel-Haenszel method. Random or fixed effect models were used according to degree of heterogeneity and subgroup analyses were performed to address heterogeneity.

MAIN RESULTS

Four studies were eligible for inclusion. There was a non statistically significant benefit of n-3 therapy for maintaining remission (RR 0.64; 95%CI 0.4 to 1.03; P = 0.07). However, the studies were both clinically and statistically heterogeneous (P = 0.01, I(2) = 72%). Three studies used enteric coated capsules (positive effects) and one ordinary gelatin capsules (no advantage). Subgroup analyses of studies which used enteric coated capsules revealed a statistically significant benefit for maintenance of remission (RR 0.49; 95% CI 0.35 to 0.69; RD 0.31; 95% CI 0.19 to 0.43); number needed to treat to prevent relapse in 1 year was 3 (95% CI 2 to 5; I(2) = 19%). However, the total number of patients enrolled in these studies was small (n = 166). No significant adverse events were recorded in any of the studies and not enough data were available to analyze the other secondary outcomes.

AUTHORS' CONCLUSIONS

Omega 3 fatty acids are safe and may be effective for maintenance of remission in CD when used in enteric coated capsules. However, there are not sufficient data to recommend the routine use of n-3 for maintenance of remission in CD. The small number of patients in the included studies warrants further larger RCTs.

Protective role of eicosapentaenoate-lipoate (EPA-LA) derivative in combating oxidative hepatocellular injury in hypercholesterolemic atherogenesis

The aim of the present study is to evaluate the effect of eicosapentaenoic acid (EPA), dl-alpha-lipoic acid (LA) and eicosapentaenoate-lipoate (EPA-LA) derivative on the atherogenic disturbances in hypercholesterolemic atherogenic animals. Eight groups of male Wistar rats were employed in this study, wherein four groups were fed with a high cholesterol diet (rat chow supplemented with 4% cholesterol and 1% cholic acid; HCD) for 30 days, among which, three groups of rats were also treated with either EPA (35 mg/kg body weight/day, oral gavage), LA (20 mg/kg body weight/day, oral gavage) or EPA-LA derivative (50 mg/kg body weight/day, oral gavage) commencing from 16th day of the experimental period. The remaining four groups served as control and EPA, LA and EPA-LA derivative treated drug controls. Abnormal increases in the levels of malondialdehyde, protein carbonyl and 8-hydroxy-2-deoxyguanosine, as well as depressed antioxidants status, were observed in hepatic tissue of HCD fed rats. HCD induced abnormal elevation in the activities of hepatic lactate dehydrogenase, aminotransferases and alkaline phosphatase (ALP) and was accompanied by increased hepatic cholesterol level and altered fatty changes in the histology of liver. These changes were restored partially in the EPA and LA administered groups. However, the combined derivative EPA-LA almost ameliorated the hypercholesterolemic-oxidative changes in the HCD fed rats. The results of this study present oxidative injury induced by hypercholesterolemic diet and administration of the combination treatment of EPA-LA afforded sound protection against lipemic-oxidative injury.

Attenuation of serum lipid abnormalities and cardiac oxidative stress by eicosapentaenoate-lipoate (EPA-LA) derivative in experimental hypercholesterolemia

BACKGROUND

Dietary cholesterol plays an important role in development of atherogenesis and cardiovascular disease. We explored the lipemic-oxidative injury in the hypercholesterolemic atherogenic animals. The effects of eicosapentaenoic acid (EPA), dl-alpha-lipoic acid (LA) and eicosapentaenoate-lipoate derivative (EPA-LA) were tested for their efficacy in controlling the atherogenic disturbances.

METHODS

Four groups of male Wistar rats were fed with a high cholesterol diet (rat chow supplemented with 4% cholesterol and 1% cholic acid; HCD) for 30 days. Of these groups, 3 groups of rats were treated with either EPA (oral gavage, 35 mg/kg body weight/day), LA (oral gavage, 20 mg/kg body weight/day) or EPA-LA derivative (oral gavage, 50 mg/kg body weight/day) from 16th day to 30th day of the experimental period.

RESULTS

HCD induced abnormal increase in lipid peroxidation and serum cholesterol, triglyceride, LDL and VLDL, and a decreased HDL concentration. Altered activity of cardiac and serum creatine kinase, accompanied by a depressed cardiac enzymatic and nonenzymatic antioxidants defense system were observed in HCD fed rats. These changes were partially restored in the EPA and LA treated groups, however, their combined derivative EPA-LA more effectively restored the altered parameters near to that of control (P<0.05).

CONCLUSION

Lipid abnormalities and oxidative injury were induced by a hypercholesterolemic diet. Administration of the combination treatment of EPA-LA afforded protection against the lipemic-oxidative injury.

Fish oil before cardiac surgery: neutrophil activation is unaffected but myocardial damage is moderated

Could pre-operative dietary intervention with fish oil reduce neutrophil activation and myocardial damage associated with cardiopulmonary bypass (CPB)? Patients were randomised to receive either 8 g/day fish oil (n=22) or placebo (n=18) for 6 weeks. Neutrophil activation, apoptosis and cardiac damage were measured. Demographics and operative variables were similar. Fish oil diet decreased plasma VLDL from 0.69+/-0.34 to 0.51+/-0.24 mmol/l and triglycerides from 1.68+/-0.70 to 1.39+/-0.54 mmol/l. HDL cholesterol increased from 0.94+/-0.27 to 1.03+/-0.26 mmol/l demonstrating significant treatment effects (P=0.007, 0.02 and 0.0003, respectively) as well as compliance with treatment. There were no significant differences in ex vivo N-formyl-methionyl-leucyl-phenylalanine-stimulated neutrophil superoxide anion generation or myeloperoxidase release at recruitment, pre-operatively and at end-CPB. Apoptosis at end-CPB was equally reduced in both groups from 23+/-9% to 13+/-4% in the fish oil group (P<0.001) and 35+/-14% to 15+/-3% in the placebo group (P=0.001). At end-CPB overall troponin I levels averaged 0.91+/-0.60 ng/ml which clearly exceeded diagnostic levels (0.15 ng/ml). At 24h troponin I fell significantly in the fish oil group to 46+/-23% of end-CPB levels (P=0.0002) whereas it peaked in the placebo group to 107+/-72% (P=0.098 vs. end-CPB); this difference was significant: P=0.013. At 48 h the placebo-treated patients had higher troponins but not significantly so (P=0.059). Area-under-the-curve analysis did not conclusively support this (P=0.068). We conclude that fish oil did not significantly decrease post-CPB neutrophil activation (as detected ex vivo) but may moderate post-operative myocardial damage.

Effect of fish and fish oil-derived omega-3 fatty acids on lipid oxidation

There is evidence that omega-3 (omega3) fatty acids derived from fish and fish oils reduce the risk of cardiovascular disease via mechanisms underlying atherosclerosis, thrombosis and inflammation. Despite these benefits, there has been concern that these fatty acids may increase lipid peroxidation. However, the in vivo data to date are inconclusive, due in part to limitations in the methodologies. In this regard, our findings using the measurement of F(2)-isoprostanes, a reliable measure of in vivo lipid peroxidation and oxidant stress, do not support adverse effects of omega3 fatty acids on lipid peroxidation.

Renal effects of parenteral fish oil administered to heart-beating organ donors and renal-transplant recipients: a tolerance study

BACKGROUND & AIMS

Nutrition can interfere with organ function during the different stages of transplantation. Oral fish oil supplementation to kidney transplant recipients has been found to improve renal function. The aim of the present study was to determine the safety and tolerance of intravenous administration of fish-oil emulsion to heart-beating brain-dead donors and, subsequently, to the kidney recipients, and to assess its effects on renal function.

METHODS

A lipid emulsion enriched with omega-3 fatty acids (MLF 541) was given intravenously to 8 heart-beating, brain-dead organ donors for up to 4 h before organ harvesting and to the kidney recipients for 5 days postoperatively. Hemodynamic, biochemistry and hematological parameters were measured before and at the end of lipid administration in the donors and on posttransplantation days 1, 5, 30 and 180 in the recipients. Findings in the recipients were compared with a concurrent control group.

RESULTS

There were no significant changes in hemodynamic or laboratory parameters during the MLF infusion in the donors or the 5 days of MLF administration in the recipients. Blood urea nitrogen and serum creatinine levels decreased over time in both the study and control recipients (P < 0.05 for both), with no significant between-group difference at any of the time points studied.

CONCLUSIONS

Administration of MLF 541 is safe in organ donors and in kidney recipients. Further studies involving nutrients as pharmacological agents in organ transplantation are warranted.

Effect of eicosapentaenoic acid and docosahexaenoic acid on oxidative stress and inflammatory markers in treated-hypertensive type 2 diabetic subjects

n-3 fatty acids reduce the risk of cardiovascular disease via a number of possible mechanisms. Despite this, there has been concern that these fatty acids may increase lipid peroxidation. The data in vivo are inconclusive, due in part to limitations in the methodologies. In this regard, the measurement of F2-isoprostanes provides a reliable assessment of in vivo lipid peroxidation and oxidant stress. This study aimed to assess the effects of supplementation with purified eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), the two major n-3 fatty acids, on urinary F2-isoprostanes and markers of inflammation, in type 2 diabetic patients. In a double-blind, placebo controlled trial of parallel design, 59 nonsmoking, treated-hypertensive, type 2 diabetic subjects, were randomized to 4 g daily of purified EPA, DHA, or olive oil for 6 weeks, while maintaining their usual diet. F2-isoprostanes, measured using gas chromatography-mass spectrometry in 24 h urines and C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), were measured before and after intervention. Thirty-nine men and 12 women aged 61.2 +/- 1.2 years, with body mass index (BMI), 29.5 +/- 0.5 kg/m2; 24 h blood pressure, 138/73 mmHg; HbA1c, 7.3 +/- 0.1% and fasting glucose, 7.9 +/- 0.2 mmol/l completed the intervention. Baseline urinary F2-isoprostanes were positively associated with HbA1c (p=.011) and fasting glucose (p=.032). Relative to the olive oil group, postintervention urinary F2-isoprostanes were decreased 19% by EPA (p=.017) and 20% by DHA (p=.014). There were no significant changes in CRP, IL-6, and TNF-alpha following EPA or DHA supplementation. In regression analysis, Delta F2-isoprostanes were positively associated with Delta HbA1c (p=.007) independent of treatment group; and with Delta TNF-alpha (p=.034) independent of age, gender, BMI, and treatment group. There were no associations with Delta CRP or Delta IL-6. This study is the first report demonstrating that either EPA or DHA reduce in vivo oxidant stress without changing markers of inflammation, in treated hypertensive, type 2 diabetic subjects.

Intestinal graft-versus-host disease: mechanisms and management

Allogeneic haematopoietic stem cell transplantation remains the treatment of choice for a number of malignancies. However, graft-versus-host disease (GVHD) has long been regarded as a serious complication of this procedure. Although GVHD may affect any organ, intestinal GVHD is particularly important because of its frequency, severity and impact on the general condition of the patient. Recent studies have led to progressive elucidation of the mechanism of GVHD. Donor T cells are critical for the induction of GVHD, because depletion of T cells from bone marrow grafts effectively prevents GVHD but also results in an increase of leukaemia relapse. It has been shown that the gastrointestinal tract plays a major role in the amplification of systemic disease because gastrointestinal damage increases the translocation of endotoxins, which promotes further inflammation and additional gastrointestinal damage. Consequently, the management of intestinal GVHD (and the intestine itself) is a subject that should be highlighted. In this article, approaches to the prevention of intestinal GVHD are discussed after being classified into three categories: regimens in common clinical use, regimens under investigation and original regimens used at our hospital. The standard regimen that is used most widely for prevention of GVHD is cyclosporin plus short-term methotrexate. Corticosteroids can be added to this regimen but careful consideration of the adverse effects of these hormones should be considered. Tacrolimus is a newer, more potent alternative to cyclosporin. T-cell depletion (TCD) after transplantation has been shown to prevent acute GVHD, however, the survival benefit of TCD has not been as great as expected. Mycophenolate mofetil can be useful for the treatment of acute GVHD as part of combination therapy. Regimens currently under investigation in animal experiments include suppression of inflammatory cytokines and inhibition of T-cell activation, and, specifically at our institution, hepatocyte growth factor gene therapy. The evidence-based therapy used at our institution includes systemic antibacterial therapy (including eradication of intestinal bacteria) to prevent the intestinal translocation of lipopolysaccharide and avoid the subsequent increase of various inflammatory cytokines. In addition, because of the similarities between intestinal GVHD and ulcerative colitis, sulfasalazine, betamethasone enemas and eicosapentaenoic acid have been used to treat intestinal GVHD in some patients.

Exercise, cachexia, and cancer therapy: a molecular rationale

Evidence from recent publications indicates that repeated exercise may enhance the quality of life of cancer patients. The lack of reported negative effects and the consistency of the observed benefits lead one to conclude that physical exercise may provide a low-risk therapy that can improve patients' capacity to perform activities of daily living and improve their quality of life. Repeated physical activity may attenuate the adverse effects of cancer therapy, prevent or reverse cachexia, and reduce risk for a second cancer through suppression of inflammatory responses or enhancement of insulin sensitivity, rates of protein synthesis, and anti-oxidant and phase II enzyme activities. These results most likely come about through the ability of physical exercise to attenuate a chronic inflammatory signaling process and to transiently activate the mitogen-activated protein kinase, c-Jun NH2-terminal kinase, c-Jun NH2-terminal kinase-mitogen-activated protein kinase, and nuclear factor-kappa B pathways and through its ability to enhance insulin sensitivity. Expanded molecular-based research into these areas may provide new insights into the biological mechanisms associated with cancer rehabilitation and endogenous risk.

Dietary fish oil protects against lung and liver inflammation and fibrosis in monocrotaline treated rats

The purpose of the present study was to evaluate the effectiveness of fish oil in preventing tissue pathologies associated with monocrotaline (MCT) toxicity. Twenty-four weanling rats were randomly assigned to one of two groups: (1) 12 to a group fed a diet containing 15% (w/w) corn oil (control) and (2) 12 to a group fed a diet containing fish oil (13%) and corn oil (2%) as the source of fat. Rats were fed for 4 weeks prior to MCT treatment. Six rats in each group were subcutaneously injected with MCT and six injected with its vehicle (water) and all were continued on their respective diets. All rats were sacrificed 3 weeks after injection. In rats receiving MCT, we observed severe interstitial pneumonia, septal fibrosis, vasculitis with virtual obliteration of the lumen of the small arteries and arterioles, right ventricular hypertrophy (RVH), and hepatomegaly and hepatocyte vacuole formation. Dietary fish oil significantly reduced septal fibrosis and development of pneumonia. There was a slight, but statistically insignificant decrease in vasculitis and fish oil did not prevent RVH (pulmonary hypertension). In addition, fish oil effectively protected the MCT-treated rats from development of hepatocyte vacuoles (steatosis), hepatic inflammation and vasculitis, increased presence of fibroblasts and collagen deposition in the centrilobular and, to a lesser extent, in the periportal spaces. These results suggest that lung parenchymal inflammation can be attenuated without altering the course of development of pulmonary hypertension in the MCT model. These results also indicate that fish oil protects against inflammation and fibrosis in the lung and liver, and against hepatocyte vacuole formation in MCT-treated rats.

n-3 Polyunsaturated fatty acid-enriched diet does not protect from liver injury but attenuates mortality rate in a rat model of systemic endotoxemia

OBJECTIVE

We investigated the potential of dietary fish oil containing n-3 polyunsaturated fatty acids to attenuate hepatic injury and mortality rate of rats in response to systemic endotoxemia.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University laboratory.

SUBJECTS

A total of 43 male Sprague Dawley rats.

INTERVENTIONS

Rats were fed either fish oil supplement or regular standard lab chow. After 8 wks of feeding, each diet group was subjected to a single exposure of lipopolysaccharide (Escherichia coli, 10 mg/kg intravenously) or saline. Hepatic microvascular response and liver injury were assessed by in vivo analysis of Kupffer cell phagocytic activity, leukocyte-endothelial cell interaction, nutritive sinusoidal perfusion failure, and parenchymal cell apoptosis (intravital fluorescence epi-illumination technique) as well as bile flow, serum liver enzyme activities, and tissue histomorphology.

MEASUREMENTS AND MAIN RESULTS

In animals fed a standard diet, livers at 16 hrs after lipopolysaccharide-exposure exhibited depressed Kupffer cell phagocytic activity, enhanced hepatic microvascular leukocyte activation, leukocytic tissue infiltration, sinusoidal perfusion failure, and parenchymal cell apoptosis. Hepatic microvascular injury was further accompanied by reduced bile flow and enhanced liver enzyme release. The fish oil enriched diet did not significantly change the multiple features of endotoxemia-associated liver injury; however, it maintained arterial blood pressure, systemic leukocyte count, and acid base balance and showed a tendency toward improved survival on lipopolysaccharide exposure with a 16 hr-survival rate of 80% (p =.06 vs. survival rate of 40% in animals fed a regular diet). Moreover, slightly increased serum concentrations of interleukin-10 coincided with enhanced concentrations of interleukin-6 in fish oil fed endotoxemic animals. Healthy, non-lipopolysaccharide-exposed, fish oil fed animals did not differ from those fed with the regular diet, except for dampened Kupffer cell phagocytic activity.

CONCLUSIONS

Fish oil feeding does not protect from local endotoxemia-induced hepatic microvascular dysfunction. However, dietary modulation of inflammatory mediator response by macrophages, constituting an appropriate immune response, could add to the survival advantage seen in fish oil-fed animals on exposure to lipopolysaccharide.

Oral eicosapentaenoic acid for complications of bone marrow transplantation

The 'systemic inflammatory response syndrome' (SIRS) may represent the underlying cause of complications after bone marrow transplantation (BMT). This study was conducted to determine whether blocking the etiologic factors of SIRS could improve the complications of BMT. Sixteen consecutive patients with unrelated donors were allocated alternately to two groups. Seven patients received 1.8 g/day of eicosapentaenoic acid (EPA) orally from 3 weeks before to about 180 days after transplantation, while nine patients did not. These two groups were compared with respect to complications, survival, and various cytokines and factors causing vascular endothelial damage. All seven patients receiving EPA survived and only two had grade III graft-versus-host disease (GVHD). Among the nine patients not receiving EPA, three had grade III or IV GVHD. In addition, thrombotic microangiopathy developed in four patients and cytomegalovirus disease occurred in four. Five patients died in this group. The levels of leukotriene B(4), thromboxane A(2), and prostaglandin I(2) were significantly lower in patients receiving EPA than in those not receiving it (all P < 0.01). Cytokines such as tumor necrosis factor-alpha, interferon-gamma, and interleukin-10 were also significantly decreased by EPA (P < 0.05), as were factors causing vascular endothelial damage such as thrombomodulin and plasminogen activator inhibitor-1 (P < 0.05). The survival rate was significantly higher in the group given EPA (P < 0.01). EPA significantly reduced the complications of BMT, indicating that these complications may be manifestations of the systemic inflammatory response syndrome.

Modulation of human immune and inflammatory responses by dietary fatty acids

I review the effects of the amount and composition of dietary fat on indices of human immune and inflammatory responses. A reduction in the amount of fat intake enhanced several indices of immune response, including lymphocyte proliferation, natural-killer-cell activity, cytokine production, and delayed-type hypersensitivity. When total fat intake was held constant, an increase in the intake of linoleic acid (18:2 omega-6) or arachidonic acid (20:4 omega-6) by healthy human volunteers did not inhibit many indices of immune response tested but did increase the production of inflammatory eicosanoids (prostaglandin E2 and leukotriene B4). Supplementation of human diets with omega-3 fatty acids reduced several aspects of neutrophil, monocyte, and lymphocyte functions, including the production of inflammatory mediators. Most of the studies have indicated reductions in these functions, with a minimum of 1.2 g/d of supplementation with eicosapentaenoic acid and docosahexaenoic acid for 6 wk. However, other studies concomitantly supplementing with 205 mg/d of vitamin E did not find inhibition of immune-cell functions, even with larger amounts and longer durations of supplementation with these fatty acids. One study reported that supplementation with docosahexaenoic acid selectively inhibits inflammatory responses without inhibiting T- and B-cell functions. Despite some discrepancies, fish oils have been used successfully in the management of several inflammatory and autoimmune diseases. The potential for the use of fish oils in the management of these diseases is tremendous, even though further studies are needed to establish safe and adequate intake levels of omega-3 fatty acids.

Activity of the leukocyte NADPH oxidase in whole neutrophils and cell-free neutrophil preparations stimulated with long-chain polyunsaturated fatty acids

Fish oils are known for their anti-inflammatory effects. In this paper we investigated the influence of eicosapentaenoic acid and docosahexaenoic acid (omega-3 fatty acids), as well as docosapentaenoic acid, a metabolic product of omega-3 fatty acid metabolism, on O2(-)-production catalyzed by the NADPH oxidase in whole neutrophils and in a cell-free system consisting of neutrophil membranes and cytosol. As a standard we used arachidonic acid (an omega-6 fatty acid) found in a high proportion in the Western diet, and known as an effective activator of the oxidase in both systems. Our data show that with omega-3 fatty acids, the O2(-)-production in both systems is reduced as compared to the effect of arachidonic acid. The effects are more pronounced with increasing carbon chain length and increasing numbers of double bonds. Our results suggest another mechanism besides the inhibition of eicosanoid and cytokine production to explain the beneficial effects of fish oils in reducing inflammation.

Review: the role of omega 3 fatty acids in intestinal inflammation

The role of polyunsaturated fatty acids (PUFAs) in inflammatory lesions of the intestines is the subject of increasing research. This review begins with a background discussion of the source, elongation, and desaturation of PUFAs, as well as the role they have played in the human diet through evolution. The available data and hypotheses as to how manipulation of PUFAs might effect the various components of the immune system are then provided. Possible mechanisms by which PUFAs result in immunomodulation include alterations in eicosanoid synthesis, membrane fluidity, signal transduction, intraluminal bacteria, and gene expression. Attention is then turned to the known effects that these polyunsaturated fatty acids have on the various individual components of the immune system including lymphocytes, neutrophils, and antigen presenting cells, as well as the immunoregulatory process of apoptosis. Finally, laboratory data on the role of PUFAs in necrotizing enterocolitis, and to a greater extent inflammatory bowel disease, first as demonstrated in animal models of the disease, and second in human studies are then summarized.

Eicosapentaenoic acid reduces pulmonary edema in endotoxemic rats

BACKGROUND

Recently, eicosapentaenoic acid (EPA) was found to have an anti-inflammatory effect attributable to diminished synthesis of arachidonic acid metabolites that initiate acute lung injury. We evaluated the ability of dietary EPA supplementation to prevent endotoxin-induced acute lung injury in rats.

MATERIALS AND METHODS

Rats fed a standard diet were divided randomly into two groups: for 2 weeks one group additionally was fed 1000 mg/kg/day of EPA ethyl ester emulsion (EPA rats), while in the other group the diet was supplemented with vehicle alone (control rats). Fatty acid components of alveolar macrophages (AM) were measured, as well as leukotriene (LT) B(4) and LTB(5) production by AM exposed in vitro to calcium ionophore A23187. Plasma concentrations of thromboxane (Tx) B(2), a stable metabolite of TxA(2), were examined 1 h after inducing lung injury with endotoxin (2 mg/kg iv). At 6 h, wet/dry (W/D) weight ratios were calculated for the lungs to assess pulmonary edema, and neutrophils were counted in pulmonary parenchyma and peripheral blood.

RESULTS

Arachidonic acid content and LTB(4) generation in AM were significantly lower in EPA rats than in controls; conversely, EPA content and LTB(5) generation in AM were significantly higher in the EPA group. Neutrophil counts in lung parenchyma and peripheral blood did not differ between groups, but W/D and plasma TxB(2) concentrations were significantly lower in EPA rats.

CONCLUSIONS

EPA supplementation depressed arachidonic acid content and LTB(4) generation in AM and plasma TxB(2) in our model, leading to decreased pulmonary edema.

Polyunsaturated fatty acids and inflammatory bowel disease

The rationale for supplementation with n-3 fatty acids to promote the health of the gastrointestinal tract lies in the antiinflammatory effects of these lipid compounds. The first evidence of the importance of dietary intake of n-3 polyunsaturated fatty acids was derived from epidemiologic observations of the low incidence of inflammatory bowel disease in Eskimos. The aim of this paper was to briefly review the literature on the use of n-3 fatty acids in inflammatory bowel disease (ulcerative colitis and Crohn disease), the results of which are controversial. The discrepancies between studies may reside in the different study designs used as well as in the various formulations and dosages used, some of which may lead to a high incidence of side effects. Choosing a formulation that lowers the incidence of side effects, selecting patients carefully, and paying strict attention to experimental design are critical when investigating further the therapeutic potential of these lipids in inflammatory bowel disease.

Effect of dietary fish and exercise training on urinary F2-isoprostane excretion in non-insulin-dependent diabetic patients

Despite the potential benefits of dietary treatment with marine omega3 fatty acids in cardiovascular disease, there remains concern with respect to their potential for increased lipid peroxidation. Thus far, data from in vivo studies are inconclusive. Increased lipid peroxidation has also been associated with acute exercise in some studies, but the methods have been nonspecific. The quantitation of F2-isoprostanes provides a more reliable and useful assessment of in vivo lipid peroxidation. We therefore aimed to assess the independent and combined effects of dietary omega3 fatty acids and aerobic exercise training on urinary F2-isoprostane levels in dyslipidemic non-insulin-dependent diabetic (NIDDM) patients. In a randomized controlled trial, 55 untrained, sedentary, dyslipidemic NIDDM patients were randomly assigned to a low-fat diet (30% of daily energy) with or without one daily fish meal (3.6 g omega3 fatty acids per day) and further randomized to either a moderate (55% to 65% maximal oxygen consumption [VO2max]) or light (heart rate <100 bpm) exercise training program for 8 weeks. Twenty-four-hour urine samples from 49 subjects were collected for measurement of urinary F2-isoprostanes by gas chromatography-mass spectrometry before and after intervention. The fish diets reduced urinary F2-isoprostanes by 830+/-321 pmol/24 h (20%, P = .013) relative to the low-fat diet alone. This effect was independent of age, gender, and body weight change. Moderate exercise training did not alter F2-isoprostanes. These findings show that, at least in the short-term, exercise had no effect, whereas the inclusion of regular fish meals as part of a low-fat diet reduced in vivo lipid peroxidation in dyslipidemic NIDDM patients. This response could further complement the known benefits of omega3 fatty acids and exercise favoring a reduced cardiovascular risk in diabetic patients.

Beneficial effects of omega-3 fatty acid treatment on the recovery of cardiac function after cold storage of hyperlipidemic rats

Cardiac effects of omega-3 polyunsaturated fatty acids (PUFAs) were studied in female Wister rats fed a standard diet (control [C] diet) or a high-cholesterol (HC) diet. Subgroups of rats from these groups were treated with eicosapentaenoic acid-E (EPA) or docosahexaenoic acid-95E (DHA) for 5 weeks. Although plasma total cholesterol (TC) and triglyceride (TG) levels were higher in each group fed the HC diet versus each group fed the C diet, EPA administration with the HC diet (HC + EPA) significantly (P < .05) reduced these levels. An isolated working-heart preparation was used to determine cardiac function. Cardiac output (CO) was lower in rats fed the HC diet and HC + DHA versus any of the groups fed the C diet (P < .05). In addition, left ventricular (LV) maximum differentiation of pressure-time curve (dp/dt) was lower in the rats fed the HC diet versus any of the C diet groups (P < .05). After evaluation of cardiac function in each rat, the heart was stored in a histidine-tryptophan-ketoglutarate solution for 8 hours at 4 degrees C. The heart was then reperfused, and recovery of cardiac function was evaluated. No significant differences were observed for post-preservative cardiac function within the C diet groups. However, within the HC diet groups, HC + EPA significantly (P < .05) improved the recovery of cardiac function. In addition, HC + DHA also significantly (P < .05) improved the recovery of coronary flow (CF) and LV dp/dt. No significant differences were observed for plasma TC and TG concentrations in the C diet groups. EPA administration significantly decreased cardiac levels of palmitic, oleic, and linoleic acids in the HC diet groups. No significant differences were observed for cardiac levels of free fatty acids (FFAs) within the C diet groups. Cardiac EPA and DHA levels were significantly (P < .05) elevated in EPA- or DHA-treated rats compared with the other diet-fed rats. Cardiac EPA levels were also elevated in DHA-treated rats compared with untreated rats (P < .05). These results suggest that EPA attenuates coronary and myocardial preservation injuries through an increase in serum lipids and an accumulation of myocardial FFAs resulting from a HC diet.

Reduction of hypercholesterolemic atherosclerosis by CDC-flaxseed with very low alpha-linolenic acid

Flaxseed (Type I flaxseed) with 51-55% alpha-linolenic acid in its oil and richest source of plant lignans, has been shown to reduce hypercholesterolemic atherosclerosis by 46% without lowering serum lipids. Antiatherogenic activity was claimed to be due to its alpha-linolenic acid and/or lignan content. If alpha-linolenic acid component of flaxseed is responsible for antiatherogenic activity, then, CDC-flaxseed (Type II flaxseed) which has similar oil and lignan content but has very little (2-3% of the total oil) alpha-linolenic acid would have no antiatherogenic effect. An investigation, therefore, was made of Type II flaxseed on high cholesterol diet-induced atherosclerosis and serum lipids [total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C)] in rabbits. Rabbits were assigned to four groups: Group I, Control; Group II, Type II flaxseed diet (7.5 g/kg orally daily); Group III, 1% cholesterol diet; Group IV, 1% cholesterol diet supplemented with Type II flaxseed (7.5 g/kg orally daily). Blood samples were collected before (0 time) and after 4 and 8 weeks of experimental diets for measurement of serum lipids. Aorta was removed at the end of 8 weeks for assessment of atherosclerotic plaques. Serum TC, LDL-C, TC/HDL-C, and LDL-C/HDL-C were lower in Group IV as compared to Group III by 14 and 31%, 17 and 32%, 28 and 34% and 24 and 32%, respectively, at 4 and 8 weeks. HDL-C was not affected by Type II flaxseed in hypercholesterolemic rabbit. TG and VLDL-C were markedly increased in Group IV as compared to Group III. Type II flaxseed reduced the development of atherosclerosis by 69%. Histological changes in the atherosclerotic regions were qualitatively similar in Groups III and IV. Results indicate that reduction in hypercholesterolemic atherosclerosis by Type II flaxseed is due to a decrease in serum TC and LDL-C. In conclusion, antiatherogenic activity of Type II flaxseed is not due to alpha-linolenic acid.

Fish oil and oxidative stress by inflammatory leukocytes

We investigated the effects of diets with different fatty acid composition upon the oxidative stress of inflammatory leukocytes of rats. After weaning, two groups of rats were fed isoenergetic semipurified diets for five weeks containing 5% of corn oil or menhaden oil. Polymorphonuclear leukocytes from rats fed menhaden oil diet incorporated n-3 polyunsaturated fatty acids into phospholipid membranes at the expense of arachidonic acid. These cells showed diminished superoxide production and, as a consequence, the total antioxidant status in the inflammatory exudate was increased. However, nitric oxide production was not affected by diet. Free malondialdeyde concentration increased in the exudate because of lower mitochondrial activity. These results add new aspects that help clarifying the anti-inflammatory mechanisms of n-3 polyunsaturated fatty acids.

Peroxidation of LDL from combined-hyperlipidemic male smokers supplied with omega-3 fatty acids and antioxidants

The effects of marine omega-3 polyunsaturated fatty acids (FAs) and antioxidants on the oxidative modification of LDL were studied in a randomized, double-blind, placebo-controlled trial. Male smokers (n = 41) with combined hyperlipidemia were allocated to one of four groups receiving supplementation with omega-3 FAs (5 g eicosapentaenoic acid and docosahexaenoic acid per day), antioxidants (75 mg vitamin E, 150 mg vitamin C, 15 mg beta-carotene, and 30 mg coenzyme Q10 per day), both omega-3 FAs and antioxidants, or control oils. LDL and human mononuclear cells were isolated from the patients at baseline and after 6 weeks of supplementation. LDL was subjected to cell-mediated oxidation by the patients' own mononuclear cells, as well as to Cu(2+)-catalyzed and 2,2'-azobis-(2-amidinopropane hydrochloride) (AAPH)-initiated oxidation. Extent of LDL modification was measured as lag time, the formation rate of conjugated dienes (CDs), the maximum amount of CDs formed, formation of lipid peroxides, and the relative electrophoretic mobility of LDL on agarose gels. Dietary supplementation with omega-3 FAs increased the concentration of total omega-3 FAs in LDL and reduced the concentration of vitamin E in serum. The omega-3 FA-enriched LDL particles were not more susceptible to Cu(2+)-catalyzed, AAPH-initiated, or autologous cell-mediated oxidation than control LDL. In fact, enrichment with omega-3 FAs significantly reduced the formation rate of CDs when LDL was subjected to AAPH-induced oxidation. Supplementation with moderate amounts of antioxidants significantly increased the concentration of vitamin E in serum and increased the resistance of LDL to undergo Cu(2+)-catalyzed oxidation, measured as increased lag time, reduced formation of lipid peroxides, and reduced relative electrophoretic mobility compared with control LDL. Supplementation with omega-3 FAs/antioxidants showed oxidizability of LDL similar to that of control LDL and omega-3 FA-enriched LDL. In conclusion, omega-3 FAs neither rendered the LDL particles more susceptible to undergo in vitro oxidation nor influenced mononuclear cells' ability to oxidize autologous LDL, whereas moderate amounts of antioxidants protected LDL against oxidative modification.

Omega-3 and omega-6 fatty acids in the insulin resistance syndrome. Lipid and lipoprotein metabolism and atherosclerosis

Dietary fatty acids appear to be of significant importance for several of the most-common diseases in modern societies. To obtain more knowledge about the health consequences of dietary fatty acids, we depend upon a better understanding of the mechanisms of action of these fatty acids in vivo. With regard to the IRS, omega-3 PUFA may exert beneficial effects upon many of the associated pathophysiological metabolic changes. Omega-3 PUFA reduce fasting and postprandial TG, may improve insulin sensitivity (as shown in animal experiments), decrease platelet and leukocyte reactivity, alter immunological functions, and may slightly decrease blood pressure. Omega-3 PUFA may also beneficially influence vessel wall characteristics and blood rheology. Furthermore, both types of PUFA (omega-3 and omega-6) have been shown to inhibit cardiac arrhythmias in animals. The role of omega-3 PUFA in blood clotting and fibrinolysis still remains controversial, whereas omega-6 fatty acids may lead to increased oxidation of lipoproteins. Regardless of the effects on LDL oxidizability, both types of PUFA have shown beneficial effects on the development of atherosclerosis. As yet, little is known about the effect of specific omega-6 fatty acids with respect to the IRS. Potential adverse effects of dietary PUFA must not be neglected, but should be viewed in light of the beneficial effects of these agents.

The effect of highly purified eicosapentaenoic and docosahexaenoic acids on monocyte phagocytosis in man

The n-3 fatty acids (FA) from marine sources are known to exert antiinflammatory effects on monocyte function. There is still controversy whether n-3 FA may increase the susceptibility to infections. The present study was designed to assess the effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on monocyte phagocytosis and respiratory burst activity. Fifty-eight healthy men were randomized to take a daily supplement of 3.8 g highly purified EPA (n = 20), 3.6 g DHA (n = 19), or corn oil (n = 19) for 7 wk. Mononuclear leukocytes were collected, isolated, and cryopreserved prior to and after dietary supplementation. Paired samples were analyzed in the presence of autologous serum in a crossover design. Monocyte phagocytosis and respiratory burst activity were measured by flow cytometry after ingestion of Escherichia coli. Monocytes retained their phagocytic ability and respiratory burst activity after supplementation. No reduction in internalization of bacteria was registered. Dietary n-3 FA and particularly EPA improved bacterial adherence to the monocyte surface. In the crossover experiments, there was an adverse effect of serum enriched with n-3 FA on bacterial adherence. We conclude that monocytes retain their phagocytic potential after supplementation with purified EPA and DHA.

Effects of intravenously infused fish oil on platelet fatty acid phospholipid composition and on platelet function in postoperative trauma

BACKGROUND

The aim of this study was to assess the short-term effect of IV infusion of fish oil emulsion on the fatty acid profiles of platelet phosphatidylcholine and phosphatidylethanolamine and on platelet function in postoperative patients.

METHODS

Over a 7-day period, 10 patients received a 20% soybean fat emulsion with an added 10% marine fish oil emulsion, whereas 9 controls received only 20% soybean fat emulsion.

RESULTS

By comparison with controls, in patients receiving fish oil, (1) a large increase in eicosapentaenoic acid (20:5n-3) was observed in both platelet phosphatidylcholine (1.55% +/- 0.17% vs 0.38% +/- 0.06% by weight, p < .01) and phosphatidylethanolamine 2.21% +/- 0.18% vs 0.66% +/- 0.08% by weight, p < .01); (2) eicosapentaenoic acid (20:5n-3)/arachidonic acid (20:4n-6) ratios doubled in both platelet phosphatidylcholine (p < .01) and phosphatidylethanolamine (p < .05); (3) with collagen as aggregating factor, maximal reaction speed decreased (p < .02) and latency increased (p < .002); and (4) no toxic effect, in particular no increase of postoperative bleeding and no perturbation of hepatic and renal function, was observed during the fish oil infusion.

CONCLUSIONS

A short-term IV infusion of fish oil clearly modifies the platelet composition and changes some parameters of platelet function.

Dietary flax seed in prevention of hypercholesterolemic atherosclerosis

Oxygen free radicals (OFRs) have been implicated in the development of hypercholesterolemic atherosclerosis. Flax seed is the richest source of omega-3 fatty acid and lignans. omega-3 Fatty acid suppresses the production of interleukin-1 (IL-1), tumor necrosis factor (TNF) and leukotriene B4 (LTB4), and of OFRs by polymorphonuclear leukocytes (PMNLs) and monocytes. Lignans possess anti-platelet activating factor (PAF) activity and are antioxidant. PAF, IL-1, TNF and LTB4 are known to stimulate PMNLs to produce OFRs. Flaxseed would, therefore, reduce the levels of OFRs and hence would prevent the development of hypercholesterolemic atherosclerosis. The effects of dietary flax seed on a high cholesterol diet induced atherosclerosis, lipid profile and OFR-producing activity of PMNLs (PMNL-CL) were investigated in rabbits. The rabbits were divided into 4 groups: group I, control; group II, flax seed diet (7.5 g/kg daily, orally); group III, 1% cholesterol diet; and group IV, same as group III but received flax seed (7.5 g/kg daily, orally). Blood samples were collected before and after 4 and 8 weeks on their respective diets for biochemical measurements and aortae were removed at the end of 8 weeks for estimation of atherosclerotic changes. The high cholesterol diet increased the serum level of total cholesterol (TC) and PMNL-CL without altering the levels of serum triglycerides (TG). These changes were associated with a marked development of atherosclerosis in the aorta. Flax seed reduced the development of aortic atherosclerosis by 46% and reduced the PMNL-CL without significantly lowering the serum cholesterol. Flax seed in normocholesterolemic rabbits increased serum total cholesterol and decreased PMNL-CL without significantly affecting the serum TG. Modest dietary flax seed supplementation is effective in reducing hypercholesterolemic atherosclerosis markedly without lowering serum cholesterol. Its effectiveness against hypercholesterolemic atherosclerosis could be due to suppression of enhanced production of OFRs by PMNLs in hypercholesterolemia. Dietary flax seed supplementation could, therefore, prevent hypercholesterolemia-related heart attack and strokes.

Can fish oil maintain Crohn's disease in remission?

One of the greatest challenges in managing Crohn's disease is to maintain remission. Although pharmacologic approaches to maintaining Crohn's disease in remission have significantly improved, most of the currently available modalities are associated with significant morbidity. Recently, an enteric-coated preparation of fish oil has been shown to be effective in reducing the rate of relapse in patients with Crohn's disease in remission who are at high risk of relapse. Because of minimal side effects, fish oil appears to be an ideal maintenance agent in Crohn's disease. However, until results from studies that compare the therapeutic effect of fish oil to the currently available maintenance agents are available, fish oil supplementation cannot be recommended as a sole maintenance agent at present. It does, however, seem prudent to promote a diet rich in fish oil in patients with Crohn's disease.

Effect of an enteric-coated fish-oil preparation on relapses in Crohn's disease

BACKGROUND

Patients with Crohn's disease may have periods of remission, interrupted by relapses. Because fish oil has antiinflammatory actions, it could reduce the frequency of relapses, but it is often poorly tolerated because of its unpleasant taste and gastrointestinal side effects.

METHODS

We performed a one-year, double-blind, placebo-controlled study to investigate the effects of a new fish-oil preparation in the maintenance of remission in 78 patients with Crohn's disease who had a high risk of relapse. The patients received either nine fish-oil capsules containing a total of 2.7 g of n-3 fatty acids or nine placebo capsules daily. A special coating protected the capsules against gastric acidity for at least 30 minutes.

RESULTS

Among the 39 patients in the fish-oil group, 11 (28 percent) had relapses, 4 dropped out because of diarrhea, and 1 withdrew for other reasons. In contrast, among the 39 patients in the placebo group, 27 (69 percent) had relapses, 1 dropped out because of diarrhea, and 1 withdrew for other reasons (difference in relapse rate, 41 percentage points; 95 percent confidence interval, 21 to 61; P < 0.001). After one year, 23 patients (59 percent) in the fish-oil group remained in remission, as compared with 10 (26 percent) in the placebo group (P = 0.003). Logistic-regression analysis indicated that only fish oil and not sex, age, previous surgery, duration of disease, or smoking status affected the likelihood of relapse (odds ratio for the placebo group as compared with the fish-oil group, 4.2; 95 percent confidence interval, 1.6 to 10.7).

CONCLUSIONS

In patients with Crohn's disease in remission, a novel enteric-coated fish-oil preparation is effective in reducing the rate of relapse.

Fish oil may be an antidote for the cardiovascular risk of smoking

The fact that the cardiovascular risk of ex-smokers approximates that of non-smokers after two years of abstinence, implies that accelerated atherogenesis is not the chief mechanism of smoking-related heart disease. Indeed, smoking or nicotine have adverse effects on blood rheology, thrombotic risk, coronary blood flow, and risk for arrhythmias. Omega-3-rich fish oils can be expected to correct or compensate for a remarkable number of the adverse impacts of smoking/nicotine: increased plasma fibrinogen, decreased erythrocyte distensibility, increased plasma and blood viscosity, increased platelet aggregability, increased plasminogen activator inhibitor levels, vasoconstriction of the coronary bed, reduced fibrillation threshold, increased triglycerides, reduced high-density lipoprotein cholesterol, and increased production of superoxide by phagocytes. Smokers who cannot overcome their addiction should be encouraged to substitute nicotine aerosols/gum for tobacco and advised to use supplementary fish oil and other cardioprotective nutrients.

Up-regulation of intracellular signalling pathways may play a central pathogenic role in hypertension, atherogenesis, insulin resistance, and cancer promotion--the 'PKC syndrome'

The modern diet is greatly different from that of our paleolithic forebears' in a number of respects. There is reason to believe that many of these dietary shifts can up-regulate intracellular signalling pathways mediated by free intracellular calcium and protein kinase C, particularly in vascular smooth muscle cells; this disorder of intracellular regulation is given the name 'PKC syndrome'. PKC syndrome may entail either a constitutive activation of these pathways, or a sensitization to activation by various agonists. The modern dietary perturbations which tend to induce PKC syndrome may include increased dietary fat and sodium, and decreased intakes of omega-3 fats, potassium, calcium, magnesium and chromium. Insulin resistance may be both a cause and effect of PKC syndrome, and weight reduction and aerobic training should act to combat this disorder. PKC syndrome sensitizes vascular smooth muscle cells to both vasoconstrictors and growth factors, and thus promotes both hypertension and atherogenesis. In platelets, it induces hyperaggregability, while in the microvasculature it may be a mediator of diabetic microangiopathy. In vascular endothelium, intimal macrophages, and hepatocytes, increased protein kinase C activity can be expected to increase cardiovascular risk. Up-regulation of protein kinase C in stem cells may also play a role in the promotion of 'Western' fat-related cancers. Practical guidelines for combatting PKC syndrome are suggested.

Fish oil may impede tumour angiogenesis and invasiveness by down-regulating protein kinase C and modulating eicosanoid production

Inhibition of angiogenesis shows considerable promise as a strategy for treating solid malignancies. Induction of collagenase by protein kinase C plays an important role in the angiogenic process as well as in metastasis. Lipoxygenase products are required for endothelial cell mitosis, and also promote collagenase production. By down-regulating hormonal activation of protein kinase C and modulating eicosanoid metabolism, ingestion of omega-3-rich fish oils may impede angiogenesis and reduce tumor invasiveness-thus rationalizing the growth-retardant and anti-metastatic effects of fish oil feeding almost invariably seen in animal tumour models. Certain other anti-inflammatory agents-including cromolyn (an inhibitor of protein kinase C activation) and gamma-linolenic acid (which indirectly inhibits lipoxygenase) may have analogous tumour-retardant activity. Clinical application of supplemental fish oil in cancer therapy is long overdue.

Eicosanoids, fatty acids and neutrophils: their relevance to the pathophysiology of disease

PUFA and their eicosanoid metabolites are potent biological modifiers. They have beneficial effects in a number of diseases, which may result in part from their direct actions on neutrophils as well as from their ability to modulate eicosanoid biosynthesis. A consideration of their interactions with other cell types, e.g. lymphocytes and macrophages, is beyond the scope of this review. Small alterations in structure can result in large changes in the neutrophil response. This will have important implications for the further development and use of fatty acids for therapeutic purposes.

Fish oil treatment decreases superoxide anions in the myocardium and coronary arteries of atherosclerotic monkeys

BACKGROUND

This experiment sought to determine the effects of fish oil on superoxide anion production in the myocardium and coronary arteries of atherosclerotic monkeys. Recent evidence indicates that dietary supplementation with fish oil preserves normal vasomotion of atherosclerotic coronary arteries and reduces damage to the myocardium after ischemia and reperfusion, although the mechanisms remain unclear.

METHODS AND RESULTS

Adult male cynomolgus monkeys were fed an atherogenic diet with (n = 15) or without (n = 15) half the fat calories from fish oil. After 12 months, chemiluminescence of lucigenin was used to measure superoxide anion production in coronary arteries and myocardium after 1 hour of ischemia and 2 hours of reperfusion. The signals were calibrated with known quantities of xanthine and xanthine oxidase. Superoxide anion production in ischemic myocardium was (mean +/- SEM, nmol/mg dry wt per minute) 1 +/- 1 and 4 +/- 1 in monkeys fed fish oil and not fed fish oil, respectively (P < .05). Superoxide anion production in coronary arteries not exposed to ischemia and reperfusion was (nmol/mg dry wt per minute) 4 +/- 1 and 8 +/- 2 in monkeys fed fish oil and not fed fish oil, respectively (P < .05). Superoxide anion production in coronary arteries was (nmol/mg dry wt per minute) 5 +/- 2 and 16 +/- 3 in monkeys fed fish oil and not fed fish oil after ischemia and reperfusion, respectively (P < .05).

CONCLUSIONS

Dietary supplementation with fish oil reduced vascular superoxide anion production and prevented the increase in vascular and myocardial superoxide anion production that accompanied ischemia and reperfusion. These phenomena may underlie some of the beneficial cardiovascular effects of fish oil.