Distal proctocolitis and n-3 polyunsaturated fatty acids (n-3 PUFAs): the mucosal effect in situ

Dry Eye Assessment and Management (DREAM©) Study: Study design and baseline characteristics

PURPOSE

Describe trial design and baseline characteristics of participants in the DRy Eye Assessment and Management (DREAM©) Study.

DESIGN

Prospective, multi-center, randomized, double-masked "real-world" clinical trial assessing efficacy and safety of oral omega-3 (ω3) supplementation for the treatment of dry eye disease (DED).

METHODS

RESULTS: Mean age of participants was 58.0 ± 13.2 years. Mean OSDI score at baseline was 44.4 ± 14.2. Mean conjunctival staining score (scale 0-6) was 3.0 ± 1.4, corneal staining score (scale 0-15) was 3.9 ± 2.7, tear break-up time was 3.1 ± 1.5 s, and Schirmer test was 9.6 ± 6.5 mm/5 min.

CONCLUSIONS

DREAM© participants mirror real world patients who seek intervention for their DED-related symptoms despite their current treatments. Results regarding the efficacy of omega-3 supplementation will be helpful to clinicians and patients with moderate to severe DED who are considering omega-3 as a treatment. This trial design may be a model for future RCT's on nutritional supplements and DED treatments seeking to provide useful information for clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT02128763.

Actors and Factors in the Resolution of Intestinal Inflammation: Lipid Mediators As a New Approach to Therapy in Inflammatory Bowel Diseases

In the last few decades, the pathogenesis of inflammatory bowel disease (IBD) in genetically predisposed subjects susceptible to specific environmental factors has been attributed to disturbance of both the immune and non-immune system and/or to the imbalanced interactions with microbes. However, increasing evidences support the idea that defects in pro-resolving pathways might strongly contribute to IBD onset. The resolution of inflammation is now recognized as a dynamic event coordinated by specialized pro-resolving lipid mediators (LMs), which dampen inflammation-sustaining events, such as angiogenesis, release of pro-inflammatory cytokines, clearance of apoptotic cells, and microorganisms. Among these pro-resolving molecules, those derived from essential polyunsaturated fatty acids (PUFAs) have been shown to induce favorable effects on a plethora of human inflammatory disorders, including IBD. Here, we offer a summary of mechanisms involving both cellular and molecular components of the immune response and underlying the anti-inflammatory and pro-resolving properties of PUFAs and their derivatives in the gut, focusing on both ω-3 and ω-6 LMs. These fatty acids may influence IBD progression by: reducing neutrophil transmigration across the intestinal vasculature and the epithelium, preventing the release of pro-inflammatory cytokines and the up-regulation of adhesion molecules, and finally by promoting the production of other pro-resolving molecules. We also discuss the numerous attempts in using pro-resolving PUFAs to ameliorate intestinal inflammation, both in patients with IBD and mouse models. Although their effects in reducing inflammation is incontestable, results from previous works describing the effects of PUFA administration to prevent or treat IBD are controversial. Therefore, more efforts are needed not only to identify and explain the physiological functions of PUFAs in the gut, but also to unveil novel biosynthetic pathways of these pro-resolving LMs that may be dysregulated in these gut-related disorders. We suppose that either PUFAs or new medications specifically promoting resolution-regulating mediators and pathways will be much better tolerated by patients with IBD, with the advantage of avoiding immune suppression.

Complementary and Alternative Medicines Used by Patients With Inflammatory Bowel Diseases

Patients and physicians often have many questions regarding the role of complementary and alternative medicines (CAMs), or nonallopathic therapies, for inflammatory bowel diseases (IBDs). CAMs of various forms are used by more than half of patients with IBD during some point in their disease course. We summarize the available evidence for the most commonly used and discussed CAMs. We discuss evidence for the effects of herbs (such as cannabis and curcumin), probiotics, acupuncture, exercise, and mind-body therapy. There have been few controlled studies of these therapies, which have been limited by their small sample sizes; most studies have been uncontrolled. In addition, there has been a lack of quality control for herbal preparations. It has been a challenge to design rigorous, randomized, placebo-controlled trials, in part owing to problems of adequate blinding for psychological interventions, acupuncture, and exercise. These barriers have limited the acceptance of CAMs by physicians. However, such therapies might be used to supplement conventional therapies and help ease patient symptoms. We conclude that physicians should understand the nature of and evidence for CAMs for IBD so that rational advice can be offered to patients who inquire about their use. CAMs have the potential to aid in the treatment of IBD, but further research is needed to validate these approaches.

Antioxidant Supplements and Gastrointestinal Diseases: A Critical Appraisal

The gastrointestinal tract digests and absorbs dietary nutrients, protects the body against physical and chemical damage from contents in its lumen, provides immunity against external antigens, and keeps an optimum environment for the gut microbiota. These functions cannot be performed normally in several diseases of which the following are discussed here: irritable bowel syndrome and inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis. Because these diseases are associated with oxidative stress, a host of antioxidant supplements are used for maintenance and recovery of the gut functions. However, the benefits of these supplements have not been established. The available 80 human trials were rated for levels of confidence and for benefits of the antioxidant supplements. For Crohn's disease, the supplements for which clear benefits occurred in at least 2 studies were allopurinol, Boswellia serrata (frankincense or shallaki), Artemesia species (wormwood), Tripterygium wilfordii (léi gōng téng), and omega-3 fatty acids. Similar beneficial supplements for ulcerative colitis were allopurinol, Matricaria chamomilla (chamomile), Curcuma longa (curcumin in turmeric), and omega-3 fatty acids. There was also a clear benefit for ulcerative colitis in 2 studies where a multiherbal Chinese medicine preparation and an Ayurvedic medicine preparation were used. For irritable bowel syndrome, there was only a marginal benefit of some of the antioxidant supplements. Thus, some antioxidant supplements may be beneficial at certain stages of specific diseases. This is consistent with the current concept that antioxidants act by inhibiting oxidative stress pathways in a tissue- and environment-specific manner and not by simply acting as scavengers.

MAG-EPA reduces severity of DSS-induced colitis in rats

Ulcerative colitis (UC) is a chronic disease characterized by diffuse inflammation of the intestinal mucosa of the large bowel. Omega-3 (ω3) fatty acid supplementation has been associated with a decreased production of inflammatory cytokines involved in UC pathogenesis. The aim of this study was to determine the preventive and therapeutic potential of eicosapentaenoic acid monoglyceride (MAG-EPA) in an in vivo rats model of UC induced by dextran sulfate sodium (DSS). DSS rats were untreated or treated per os with MAG-EPA. Morphological, histological, and biochemical analyses were performed following MAG-EPA administrations. Morphological and histological analyses revealed that MAG-EPA pretreatment (12 days pre-DSS) and treatment (6 days post-DSS) exhibited strong activity in reducing severity of disease in DSS rats. Following MAG-EPA administrations, tissue levels of the proinflammatory cytokines TNF-α, IL-1β, and IL-6 were markedly lower compared with rats treated only with DSS. MAG-EPA per os administration decrease neutrophil infiltration in colon tissues, as depicted by myelohyperoxidase activity. Results also revealed a reduced activation of NF-κB pathways correlated with a decreased expression of COX-2 in colon homogenates derived from MAG-EPA-pretreated and treated rats. Tension measurements performed on colon tissues revealed that contractile responses to methacholine and relaxing effect induced by sodium nitroprusside were largely increased following MAG-EPA treatment. The combined treatment of MAG-EPA and vitamin E displayed an antagonistic effect on anti-inflammatory properties of MAG-EPA in DSS rats.

Altered colonic mucosal availability of n-3 and n-6 polyunsaturated fatty acids in ulcerative colitis and the relationship to disease activity

BACKGROUND AND AIMS

The polyunsaturated fatty acids (PUFA) arachidonic acid (AA, n-6) and eicosapentaenoic acid (EPA, n-3) are precursors of eicosanoids and other lipid mediators which have critical roles in inflammation. The mediators formed from the different PUFA have different potencies. We hypothesised that metabolic changes associated with colonic mucosal inflammation would modify the bioavailability of the eicosanoid precursors AA and EPA.

METHODS

Colonic mucosa biopsies were obtained from patients with ulcerative colitis and from matched controls. Inflammation was graded endoscopically and histologically. Esterified and non-esterified fatty acids were determined within the biopsies using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, respectively.

RESULTS

Biopsy samples were collected from 69 UC patients (54 providing both inflamed and non-inflamed mucosa) and 69 controls. Inflamed mucosa had higher AA (p<0.001) and lower EPA (p<0.010) contents and a higher AA:EPA ratio (p<0.001). Inflamed mucosa also had higher docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) and lower linoleic acid (LA) and α-linolenic acid (α-LNA) contents (all p<0.001), compared to non-inflamed and controls. There were significant correlations between severity of inflammation and contents of AA, DPA and DHA (positive correlations) and of LA, α-LNA and EPA (negative correlations).

CONCLUSIONS

Higher AA, AA:EPA ratio, DPA and DHA and lower LA, α-LNA and EPA are seen in inflamed mucosa in UC and correlate with severity of inflammation. This suggests an alteration in fatty acid metabolism in the inflamed gut mucosa, which may offer novel targets for intervention and should be considered if nutritional strategies are used.

Response to nutritional support and therapeutic approaches of amino acid and protein metabolism in surgical patients

The response to critical illness involves alterations in all aspects of metabolic control, favoring catabolism of body protein. In particular, body protein loss occurring as a result of the alteration of protein metabolism has been reported to be inversely correlated with the survival of critically ill patients. Despite the availability of various therapeutic modalities aiming to prevent loss of the body protein pool, such as total parenteral nutrition, enteral nutrition designed to provide excessive calories as a form of energy substrate, and protein itself, the loss of body protein cannot be prevented by any of these. Loss of the boyd protein store occurs as a consequence of the alteration of the intermediate metabolism that works for the production of energy substrate. This alteration of substrate metabolism may be linked to the alteration of protein metabolism. However, no specific factors regulating amino acid and protein metabolism have been identified. Thus, further investigations evaluating amino acid and protein metabolism are required to obtain better understanding of metabolic regulation in the body, which may lead to the development of novel and more effective therapeutic modalities for nutrition in the future.

The fatty acid profile of the erythrocyte membrane in initial-onset inflammatory bowel disease patients

BACKGROUND AND OBJECTIVES

The sudden change in the dietary habits of the Japanese population towards a European/American-style diet since the 1960s is thought to be responsible for the recent increase in the incidence of inflammatory bowel disease (IBD) in Japan. Dietary fatty acid intake influences the fatty acid profiles of vital cell membranes, which might be a source of inflammatory mediators.

METHODS

We investigated the fatty acid composition of the erythrocyte membrane in 90 healthy Japanese and 43 initial-onset IBD patients (ulcerative colitis, UC: 25; Crohn's disease, CD: 18) who had not undergone any dietary intervention to examine the role fatty acids play in the onset of IBD.

RESULTS

The erythrocyte membrane n-3/n-6 ratio of the initial-onset IBD patients was 0.42 ± 0.13, which was not significantly different from that of the healthy Japanese subjects (0.41 ± 0.13). However, the CD patients displayed a significantly lower mean percentage weight (MPW) of linoleic acid (LA) than the healthy subjects (8.25 ± 1.75 vs. 9.90 ± 1.29; p < 0.001), while their MPW of arachidonic acid (AA) was significantly higher than those of the healthy subjects and UC patients (11.22 ± 2.18 vs. 9.76 ± 1.64, p < 0.01; vs. 9.58 ± 1.97, p < 0.01, respectively). The mean delta 6-desaturation index of the CD patients was significantly higher than that of the healthy subjects (1.61 ± 0.65 vs. 1.11 ± 0.26; p < 0.001).

CONCLUSIONS

The CD patients displayed significantly higher and lower MPW of AA and LA, respectively, than the healthy subjects, suggesting that delta 6-desaturase is hyperactivated in CD. The cell membrane fatty acid profile might be a therapeutic target in CD.

SOCS3 transactivation by PPARγ prevents IL-17-driven cancer growth

Activation of the transcription factor PPARγ by the n-3 fatty acid docosahexaenoic acid (DHA) is implicated in controlling proinflammatory cytokine secretion, but the intracellular signaling pathways engaged by PPARγ are incompletely characterized. Here, we identify the adapter-encoding gene SOCS3 as a critical transcriptional target of PPARγ. SOCS3 promoter binding and gene transactivation by PPARγ was associated with a repression in differentiation of proinflammatory T-helper (TH)17 cells. Accordingly, TH17 cells induced in vitro displayed increased SOCS3 expression and diminished capacity to produce interleukin (IL)-17 following activation of PPARγ by DHA. Furthermore, naïve CD4 T cells derived from mice fed a DHA-enriched diet displayed less capability to differentiate into TH17 cells. In two different mouse models of cancer, DHA prevented tumor outgrowth and angiogenesis in an IL-17-dependent manner. Altogether, our results uncover a novel molecular pathway by which PPARγ-induced SOCS3 expression prevents IL-17-mediated cancer growth.

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.

N-3 polyunsaturated fatty acid diet therapy for patients with inflammatory bowel disease

BACKGROUND

N-3 polyunsaturated fatty acids (PUFA) are considered important pharmaconutrients for modulating mucosal immunity and therapeutic responses in patients with inflammatory bowel disease (IBD). We investigated the influence of diet therapy involving the use of an "n-3 PUFA food exchange table" (n-3DP) on the fatty acid composition of the erythrocyte membranes of IBD patients and its remission-maintaining effects.

METHODS

We analyzed the fatty acid composition of the erythrocyte membrane before and after n-3DP intervention in 20 initial-onset IBD patients who had not undergone any dietary intervention. We then analyzed it again and evaluated disease activity after 12-18 months intervention in 230 IBD patients (168 ulcerative colitis, 62 Crohn's disease; follow-up group) in whom n-3DP was introduced after remission had been achieved. The follow-up group was divided into remission and relapse groups.

RESULTS

In the 20 initial-onset patients, the mean n-3/n-6 ratio significantly increased after intervention (0.41 ± 0.16 versus 0.70 ± 0.20; P < 0.001). In the follow-up group the ratio in the remission group (n = 145) was significantly higher than that in the relapse group (n = 85) (0.65 ± 0.28 versus 0.53 ± 0.18; P < 0.001). The ratio significantly decreased in those who suffered a relapse after the beginning of treatment (P < 0.01).

CONCLUSIONS

N-3DP significantly increased the erythrocyte membrane n-3/n-6 ratio in IBD patients, and this ratio was significantly higher in the remission group, suggesting that n-3DP alters the fatty acid composition of the cell membrane and influences clinical activity in IBD patients.

Fatty acids and immune function: relevance to inflammatory bowel diseases

Fatty acids may influence immune function through a variety of mechanisms; many of these are associated with changes in fatty acid composition of immune cell membranes. Eicosanoids produced from arachidonic acid have roles in inflammation and immunity. Increased membrane content of n-3 fatty acids results in a changed pattern of production of eicosanoids, resolvins, and cytokines. Changing the fatty acid composition of immune cells also affects T cell reactivity and antigen presentation. Little attention has been paid to the influence of fatty acids on the gut-associated lymphoid tissue. However, there has been considerable interest in fatty acids and gut inflammation.

Fish nutrients decrease expression levels of tumor necrosis factor-α in cultured human macrophages

Numerous studies have demonstrated the beneficial effects of fish consumption on inflammatory markers. Until now, these beneficial effects of fish consumption have been mostly linked to the omega-3 fatty acids (FA). The objective of the present study was to examine, in vitro, whether expression levels of genes involved in the inflammatory response differ in human macrophages incubated with casein hydrolysates (CH) or fish protein hydrolysates (FPH) in the presence or absence of omega-3 FA compared with omega-3 FA alone. Peripheral blood monocytes differentiated into macrophages from 10 men were incubated in the presence of omega-3 FA (10 μM eicosapentaenoic acid and 5 μM docosahexaenoic acid) or CH or FPH (10, 100, 1,000 μg) with or without omega-3 FA for 48 h. Results demonstrate that expression levels of tumor necrosis factorα ( TNFα) had a tendency to be lower after the addition of FPH alone or CH with omega-3 FA compared with omega-3 FA treatment. Furthermore, the combination of FPH and omega-3 FA synergistically decreased expression levels of TNFα compared to treatment with omega-3 FA or FPH alone. No difference on gene expression levels of interleukin-6 was observed between treatments. In conclusion, these preliminary results suggest that the anti-inflammatory effects of fish consumption can be explained by a synergistic effect of the omega-3 FA with the protein components of fish on TNFα expression and therefore contribute to the beneficial effects of fish consumption. Hence, follow-up studies should be performed to confirm the effects of a diet rich in FPH and omega-3 FA on serum proinflammatory cytokine concentrations.

Polyunsaturated fatty acids, inflammatory processes and inflammatory bowel diseases

With regard to inflammatory processes, the main fatty acids of interest are the n-6 PUFA arachidonic acid (AA), which is the precursor of inflammatory eicosanoids like prostaglandin E(2) and leukotriene B(4), and the n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are found in oily fish and fish oils. EPA and DHA inhibit AA metabolism to inflammatory eicosanoids. They also give rise to mediators that are less inflammatory than those produced from AA or that are anti-inflammatory. In addition to modifying the lipid mediator profile, n-3 PUFAs exert effects on other aspects of inflammation like leukocyte chemotaxis and inflammatory cytokine production. Some of these effects are likely due to changes in gene expression, as a result of altered transcription factor activity. Fish oil has been shown to decrease colonic damage and inflammation, weight loss and mortality in animal models of colitis. Fish oil supplementation in patients with inflammatory bowel diseases results in n-3 PUFA incorporation into gut mucosal tissue and modification of inflammatory mediator profiles. Clinical outcomes have been variably affected by fish oil, although some trials report improved gut histology, decreased disease activity, use of corticosteroids and relapse.

Docosahexaenoic acid-enriched fish oil consumption modulates immunoglobulin responses to and clearance of enteric reovirus infection in mice

We hypothesized that consumption of the (n-3) PUFA, docosahexaenoic acid (DHA), modulates the mucosal immune response to enteric infection with respiratory enteric orphan virus (reovirus), a model intestinal pathogen. Mice were fed either AIN-93G control diet, containing 10 g/kg corn oil and 60 g/kg high oleic acid safflower oil, or AIN-93G, containing 10 g/kg corn oil and 60 g/kg DHA-enriched fish oil, for 4 wk and then orally gavaged with reovirus strain Type 1 Lang, (T1/L). Reovirus-specific IgA antibody was first detectable in the feces of mice fed a control diet at 6 d postinfection (PI) and was further elevated at 8 and 10 d PI. IgA responses in DHA-fed mice were similar at 6 and 8 d PI but greater at 10 d PI (P < 0.05). Both reovirus-specific serum IgA and IgG(2a) were comparably induced in mice fed control or DHA diets. Reovirus-specific IgA and IgG(2a) secretion by ex vivo Peyer's patch, lamina propria, and spleen cultures derived from control and DHA groups were comparable. Although both groups carried similar numbers of reovirus plaque forming units per intestine, DHA-fed mice shed nearly 10 times more viral RNA in feces than control mice at 2, 4, and 6 d PI (P < 0.05). However, viral RNA was not detectable in either group at 8 and 10 d. Taken together, these data suggest that DHA consumption did not markedly alter mucosal or systemic Ig responses to reovirus but delayed clearance of the virus from the intestinal tract.

Fish oil for induction of remission in ulcerative colitis

BACKGROUND

Fish oil supplements, which are rich in n-3 fatty acids, may reduce inflammation, decrease the need for anti-inflammatory drugs, and promote normal weight gain in people with ulcerative colitis.

OBJECTIVES

This review evaluates the efficacy of fish oil for induction of remission in ulcerative colitis using all available randomised controlled trials.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL), PUBMED, EMBASE, CINAHL, the database of ongoing trials and the reference lists of all publications of included or excluded trials were searched.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials with active ulcerative colitis patients who were treated with fish oil.

DATA COLLECTION AND ANALYSIS

The reviewers performed study selection, assessment of methodological quality by using different approaches: including Cochrane assessment of allocation concealment and Jadad quality assessment score. Data extraction forms were used by the two reviewers to extract the data independently. Authors were contacted for additional information.

MAIN RESULTS

Six studies were included. Three were of cross-over design and three were of parallel design. No data were pooled for analysis due to differences in outcomes and methodology among the included studies. One small study shows a positive benefit for induction of remission (RR 19.00; 95% CI 1.27 to 284.24). Some of the other included studies show some positive benefits for secondary outcomes. However, these results need to be interpreted with caution due to small study size and poor study quality.

AUTHORS' CONCLUSIONS

The current data does not allow for a definitive conclusion regarding the efficacy of fish oil. There is no adequate information to make recommendations for clinical practice. More research is required.

Randomized Clinical Trial of the Effects of Perioperative Use of Immune-enhancing Enteral Formula on Metabolic and Immunological Status in Patients Undergoing Esophagectomy

BACKGROUND

Although perioperative immune-enhancing enteral formula (IEEF) is effective to decrease the rate of infectious complications, it is not clear whether perioperative use of IEEF decreases the incidence of postoperative complications and improves clinical outcome in patients who have undergone esophagectomy. A prospective randomized clinical trial was performed to examine the effects of perioperative IEEF on nutritional and immunological status in patients with esophageal carcinoma who have been treated with esophagectomy.

METHODS

A total of 30 patients were randomly assigned to two groups, each receiving 3 days of preoperative and postoperative enteral nutrition through jejunostomy started within 24 h after operation, either with immune-enhancing enteral formula (group IEEF, n = 16) or with regular polymeric enteral formula (group C, n = 14). Preoperative and postoperative nutritional and immunological parameters and clinical outcome were examined.

RESULTS

A significant increase in the serum concentration of ornithine was noted in group IEEF and it peaked at 5 days after surgery. The equivalent values were significantly lower in group C. There was no difference in serum dochosahexaic acid between the two groups. The n-3/n-6 fatty acid ratio in group IEEF was significantly higher than in group C at 7 days after surgery. Peripheral percent lymphocyte fraction and total lymphocyte count in group IEEF were both significantly higher than those in group C. While T cell fraction of peripheral lymphocytes in group IEEF at 3 days after surgery, B cell fraction in group IEEF at 5 and 7 days after surgery was significantly higher than those in group C, suggesting that perioperative IEEF caused a shift towards B cell proliferation.

CONCLUSIONS

Perioperative use of IEEF caused a significant increase in the total lymphocyte count at 3 and 5 days after operation and caused a shift toward B cell proliferation, which may possibly be beneficial to decrease the incidence of postoperative infectious complications.

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.

Differential immunomodulation with long-chain n-3 PUFA in health and chronic disease

The balance of intake of n-6 and n-3 PUFA, and consequently their relative incorporation into immune cells, is important in determining the development and severity of immune and inflammatory responses. Some disorders characterised by exaggerated inflammation and excessive formation of inflammatory markers have become among the most important causes of death and disability in man in modern societies. The recognition that long-chain n-3 PUFA have the potential to inhibit (excessive) inflammatory responses has led to a large number of clinical investigations with these fatty acids in inflammatory conditions as well as in healthy subjects. The present review explores the presence of dose-related effects of long-chain n-3 PUFA supplementation on immune markers and differences between healthy subjects and those with inflammatory conditions, because of the important implications for the transfer of information gained from studies with healthy subjects to patient populations, e.g. for establishing dose levels for specific applications. The effects of long-chain n-3 PUFA supplementation on ex vivo lymphocyte proliferation and cytokine production by lymphocytes and monocytes in healthy subjects have been studied in twenty-seven, twenty-five and forty-six treatment cohorts respectively, at intake levels ranging from 0.2 g EPA+DHA/d to 7.0 g EPA+DHA/d. Most studies, particularly those with the highest quality study design, have found no effects on these immune markers. Significant effects on lymphocyte proliferation are decreased responses in seven of eight cohorts, particularly in older subjects. The direction of the significant changes in cytokine production by lymphocytes is inconsistent and only found at supplementation levels > or =2.0 g EPA+DHA/d. Significant changes in inflammatory cytokine production by monocytes are decreases in their production in all instances. Overall, these studies fail to reveal strong dose-response effects of EPA+DHA on the outcomes measured and suggest that healthy subjects are relatively insensitive to immunomodulation with long-chain n-3 PUFA, even at intake levels that substantially raise their concentrations in phospholipids of immune cells. In patients with inflammatory conditions cytokine concentrations or production are influenced by EPA+DHA supplementation in a relatively large number of studies. Some of these studies suggest that local effects at the site of inflammation might be more pronounced than systemic effects and disease-related markers are more sensitive to the immunomodulatory effects, indicating that the presence of inflamed tissue or 'sensitised' immune cells in inflammatory disorders might increase sensitivity to the immunomodulatory effects of long-chain n-3 PUFA. In a substantial number of these studies clinical benefits related to the inflammatory state of the condition have been observed in the absence of significant effects on immune markers of inflammation. This finding suggests that condition-specific clinical end points might be more sensitive markers of modulation by EPA+DHA than cytokines. In general, the direction of immunomodulation in healthy subjects (if any) and in inflammatory conditions is the same, which indicates that studies in healthy subjects are a useful tool to describe the general principles of immunomodulation by n-3 PUFA. However, the extent of the effect might be very different in inflammatory conditions, indicating that studies in healthy subjects are not particularly suitable for establishing dose levels for specific applications in inflammatory conditions. The reviewed studies provide no indications that the immunomodulatory effects of long-chain n-3 PUFA impair immune function or infectious disease resistance. In contrast, in some conditions the immunomodulatory effects of EPA+DHA might improve immune function.

Effects of long-term continuous use of immune-enhancing enteral formula on nutritional and immunologic status in non-surgical patients

OBJECTIVE

Although the perioperative use of immune-enhancing enteral formula (IEEF) effectively reduces the rate of infectious complications, whether chronic use of IEEF is beneficial is unknown. A prospective randomized clinical trial was performed to examine the safety and effectiveness of long-term IEEF on nutritional and immunologic status in non-surgical patients receiving total enteral nutrition through the gastrostomy access route.

METHODS

A total of 30 patients were randomly assigned to two groups in which they received total enteral nutrition, an IEEF (n = 15) or a regular polymeric enteral formula (control group; n = 15) for 12 wk. Nutritional and immunologic variables were periodically examined.

RESULTS

Serum concentrations of insulin-like growth factor-I increased significantly for the IEEF group throughout the study. Although serum concentrations of dihomo-gamma-linoleic acid decreased significantly in the IEEF group, serum concentrations of eicosapentaenoic acid and docosahexaenoic acid increased significantly, as did concentrations of serum arginine and ornithine. The CD4/CD8 ratio and natural killer cell activity also increased for the IEEF group, but the differences were not significant. The B-cell fraction increased and the T-cell fraction of peripheral lymphocytes decreased for the IEEF group. Neither infectious nor non-infectious complications occurred during the study period in either group, except for a significant increase in serum urea nitrogen and uric acid concentrations for the IEEF group.

CONCLUSION

Long-term use of IEEF is safe in non-surgical patients and results in a significant increase in serum insulin-like growth factor-I concentrations in association with increased humoral immunity.

n-3 polyunsaturated fatty acids, inflammation, and inflammatory diseases

Inflammation is part of the normal host response to infection and injury. However, excessive or inappropriate inflammation contributes to a range of acute and chronic human diseases and is characterized by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids (prostaglandins, thromboxanes, leukotrienes, and other oxidized derivatives), other inflammatory agents (e.g., reactive oxygen species), and adhesion molecules. At sufficiently high intakes, long-chain n-3 polyunsaturated fatty acids (PUFAs), as found in oily fish and fish oils, decrease the production of inflammatory eicosanoids, cytokines, and reactive oxygen species and the expression of adhesion molecules. Long-chain n-3 PUFAs act both directly (e.g., by replacing arachidonic acid as an eicosanoid substrate and inhibiting arachidonic acid metabolism) and indirectly (e.g., by altering the expression of inflammatory genes through effects on transcription factor activation). Long-chain n-3 PUFAs also give rise to a family of antiinflammatory mediators termed resolvins. Thus, n-3 PUFAs are potentially potent antiinflammatory agents. As such, they may be of therapeutic use in a variety of acute and chronic inflammatory settings. Evidence of their clinical efficacy is reasonably strong in some settings (e.g., in rheumatoid arthritis) but is weak in others (e.g., in inflammatory bowel diseases and asthma). More, better designed, and larger trials are required to assess the therapeutic potential of long-chain n-3 PUFAs in inflammatory diseases. The precursor n-3 PUFA alpha-linolenic acid does not appear to exert antiinflammatory effects at achievable intakes.

Traitements nutritionnels au cours des MICI :où en est-on ?

Protein-energy malnutrition and specific nutrient deficiencies are common in inflammatory bowel diseases (IBD), more particularly in Crohn's disease. In adults, the use of artificial nutrition is indicated in the event of malnutrition, short bowel syndrome, or IBD refractory to all other treatments. In children, enteral nutrition has a place as first-line treatment to avoid side effects of corticosteroids on growth. The use, as a therapeutic tool, of specific nutrients (n-3 fatty acids, glutamine, antioxydant vitamins and minerals, TGF-beta, probiotics...) seems interesting at the pathophysiological level. Nevertheless, these nutrients are still under evaluation and there are not enough available studies to recommend them in clinical routine. A very promising solution is the use of probiotics for the treatment of refractory pouchitis.

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Dietary olive oil supplemented with fish oil, rich in EPA and DHA (n-3) polyunsaturated fatty acids, attenuates colonic inflammation in rats with DSS-induced colitis

Previous studies proposed a protective role of the dietary intake of (n-3) PUFA in human inflammatory bowel disease (IBD), but almost no studies have been performed using olive oil. The aims of the present study were to test the beneficial effects of an olive oil-based diet with or without fish oil, rich in (n-3) PUFA, in the dextran sodium sulfate (DSS) model of rat colitis and to elucidate the mechanisms involved in their potential beneficial effects, with special attention to the production of some of the mediators involved in the intestinal inflammatory response, such as leukotriene B(4) (LTB(4)), tumor necrosis factor alpha (TNFalpha) and nitric oxide (NO). Rats were fed the different diets for 2 wk before colitis induction and thereafter until colonic evaluation 15 d later. Colitic rats fed the olive oil-based diet had a lower colonic inflammatory response than those fed the soybean oil diet, and this beneficial effect was increased by the dietary incorporation of (n-3) PUFA. A restoration of colonic glutathione levels and lower colonic NO synthase expression occurred in all colitic rats fed an olive oil diet compared with the control colitic group that consumed the soybean oil diet. However, (n-3) PUFA incorporation into an olive oil diet significantly decreased colonic TNFalpha and LTB(4) levels compared with colitic rats that were not supplemented with fish oil. These results affirm the benefits of an olive oil diet in the management of IBD, which are further enhanced by the addition of (n-3) PUFA.

Omega 3 fatty acids for prevention and treatment of cardiovascular disease

BACKGROUND

It has been suggested that omega 3 (W3, n-3 or omega-3) fats from oily fish and plants are beneficial to health.

OBJECTIVES

To assess whether dietary or supplemental omega 3 fatty acids alter total mortality, cardiovascular events or cancers using both RCT and cohort studies.

SEARCH STRATEGY

Five databases including CENTRAL, MEDLINE and EMBASE were searched to February 2002. No language restrictions were applied. Bibliographies were checked and authors contacted.

SELECTION CRITERIA

RCTs were included where omega 3 intake or advice was randomly allocated and unconfounded, and study duration was at least six months. Cohorts were included where a cohort was followed up for at least six months and omega 3 intake estimated.

DATA COLLECTION AND ANALYSIS

Studies were assessed for inclusion, data extracted and quality assessed independently in duplicate. Random effects meta-analysis was performed separately for RCT and cohort data.

MAIN RESULTS

Forty eight randomised controlled trials (36,913 participants) and 41 cohort analyses were included. Pooled trial results did not show a reduction in the risk of total mortality or combined cardiovascular events in those taking additional omega 3 fats (with significant statistical heterogeneity). Sensitivity analysis, retaining only studies at low risk of bias, reduced heterogeneity and again suggested no significant effect of omega 3 fats. Restricting analysis to trials increasing fish-based omega 3 fats, or those increasing short chain omega 3s, did not suggest significant effects on mortality or cardiovascular events in either group. Subgroup analysis by dietary advice or supplementation, baseline risk of CVD or omega 3 dose suggested no clear effects of these factors on primary outcomes. Neither RCTs nor cohorts suggested increased relative risk of cancers with higher omega 3 intake but estimates were imprecise so a clinically important effect could not be excluded.

REVIEWERS' CONCLUSIONS

It is not clear that dietary or supplemental omega 3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population. There is no evidence we should advise people to stop taking rich sources of omega 3 fats, but further high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health. There is no clear evidence that omega 3 fats differ in effectiveness according to fish or plant sources, dietary or supplemental sources, dose or presence of placebo.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.

A review of the safety of DHA45-oil

Polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA), are natural constituents of the human diet; however, dietary intakes of these fatty acids are below recommended values. The main dietary source of DHA is fatty fish, with lesser amounts provided by shellfish, marine mammals, and organ meats. The addition to traditional food products of refined oils produced by marine microalgae represents potential sources of supplemental dietary DHA. DHA45-oil is manufactured through a multi-step fermentation and refining process using a non-toxigenic and non-pathogenic marine protist. Comprising approximately 45% DHA, and lesser concentrations of palmitic acid and docosapentaenoic acid, DHA45-oil is intended for use in foods as a dietary source of DHA. The safety of DHA45-oil was evaluated in various genotoxicity and acute, subchronic, and reproductive toxicity studies. DHA45-oil produced negative results in genotoxicity assays and demonstrated a low acute oral toxicity in mice and rats. Dietary administration of DHA45-oil to rats in subchronic and one-generation reproductive studies produced results consistent with those observed in oral studies using high concentrations of omega-3 PUFAs from fish or other microalgal-derived oils. The results of these studies, as well as those of various published metabolic, toxicological, and clinical studies with DHA-containing oils, support the safety of DHA45-oil as a potential dietary source of DHA.

Polyunsaturated fatty acids and inflammatory diseases

Inflammation is overall a protective response, whose main goal is to liberate the human being of cellular lesions caused by micro-organisms, toxins, allergens, etc., as well as its consequences, and of death cells and necrotic tissues. Chronic inflammation, which is detrimental to tissues, is the basic pathogenic mechanism of hypersensitivity reactions against xenobiotics. Other frequent pathologies, for instance atherosclerosis, chronic hepatitis, inflammatory bowel disease (IBD), liver cirrhosis, lung fibrosis, psoriasis, and rheumatoid arthritis are also chronic inflammatory diseases. Chemical mediators of inflammation are derived from blood plasma or different cell-type activity. Biogenic amines, eicosanoids and cytokines are within the most important mediators of inflammatory processes. The different activities of eicosanoids derived from arachidonic acid (20:4 n-6) versus those derived from eicosapentaenoic acid (20:5 n-3) are one of the most important mechanisms to explain why n-3, or omega-3, polyunsaturated fatty acids (PUFA) exhibit anti-inflammatory properties in many inflammatory diseases. Dietary supplements ranging 1-8 g per day of n-3 PUFA have been reportedly beneficial in the treatment of IBD, eczema, psoriasis and rheumatoid arthritis. In addition, recent experimental studies in rats with experimental ulcerative colitis, induced by intrarectal injection of trinitrobenzene sulphonic acid, have documented that treatment with n-3 long-chain PUFA reduces mucosal damage as assessed by biochemical and histological markers of inflammation. Moreover, the defence antioxidant system in this model is enhanced in treated animals, provided that the n-3 PUFA supply is adequately preserved from oxidation.

Dietary fish oil increases acetylcholine- and eicosanoid-induced contractility of isolated rat ileum

The long-chain (n-3) polyunsaturated fatty acids (PUFA) have been reported to exhibit health benefits and healing properties for the gastrointestinal tract. The aim of this study was to investigate the effects of dietary fish oil supplementation on the in vitro contractility of gut tissue. Rats (9 wk old) were fed synthetic diets supplemented with 170 g/kg Sunola oil (SO; 850 g/kg as oleic acid [18:1(n-9)]) or with 100 g/kg of the SO replaced by saturated animal fat (SF) or fish oil (FO) for 4 wk. In the colon, there was no difference in the sensitivity (50% effective concentration) or the maximal contraction among the three dietary groups induced by acetylcholine or 8-iso-prostaglandin (PG)E(2) with the rat colon being relatively insensitive to the thromboxane mimetic U-46619. However, in the ileum, the FO group had greater maximal contractions induced by acetylcholine and 8-iso-PGE(2) compared with the SO and SF groups (P < 0.05), and greater maximal contractions induced by PGE(2), PGF(2alpha) and U-46619 compared with the SF group (P < 0.05). FO feeding increased the incorporation of (n-3) PUFA (eicosapentaenoic [20:5(n-3)], docosapentaenoic [22:5(n-3)] and docosahexaenoic acids [22:6(n-3) primarily at the expense of (n-6) PUFA (linoleic [18:2(n-6)] and arachidonic acids [20:4(n-6)]) in the ileum and colon phospholipid fatty acids (P < 0.05). The FO group had a lower cecal digesta pH (P < 0.001) and a greater butyrate concentration than the SF group (P < 0.05). These results suggest that dietary (n-3) PUFA may modulate the contractility of the small intestine.