Association of n-3 and n-6 long-chain polyunsaturated fatty acids in plasma lipid classes with inflammatory bowel diseases

Association of serum lipids with inflammatory bowel disease: a systematic review and meta-analysis

Background

Serum lipid levels seem to be abnormal in Inflammatory bowel disease (IBD). However, the specific manifestation of abnormal serum lipid levels in IBD are heterogeneous among studies and have not been sufficiently determined yet.

Methods

PubMed, EMBASE, and Cochrane Library databases were searched. Serum lipid levels were compared between IBD patients and Health individuals, Crohn's (CD) and ulcerative colitis (UC), active and inactive, mild and non-mild patients, respectively. Meta-analyses were performed by using a random-effect model. Weight mean difference (WMD) with 95% confidence intervals (CIs) were calculated.

Results

Overall, 53 studies were included. Compared with healthy controls, IBD patients had significantly lower TC (WMD = -0.506, 95%CI = -0.674 to -0.338, p < 0.001), HDL-c (WMD = -0.122, 95%CI = -0.205 to -0.039, p = 0.004), and LDL-c (WMD = -0.371, 95%CI = -0.547 to -0.194, p < 0.001) levels. CD groups had a significantly lower TC (WMD = -0.349, 95%CI = -0.528 to -0.170, p < 0.0001) level as compared to UC groups. Active IBD and non-mild UC groups had significantly lower TC (WMD = -0.454, 95%CI = -0.722 to -0.187, p = 0.001) (WMD =0.462, 95%CI = 0.176 to 0.748, p = 0.002) and LDL-c (WMD = -0.225, 95%CI = -0.445 to -0.005, p = 0.045) (WMD =0.346, 95%CI = 0.084-0.609, p = 0.010) levels as compared to inactive IBD and mild UC groups, respectively.

Conclusion

The overall level of serum lipids in IBD patients is lower than that of healthy individuals and is negatively associated with disease severity.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022383885.

There Is a Differential Pattern in the Fatty Acid Profile in Children with CD Compared to Children with UC

Background: Crohn’s disease (CD) and Ulcerative Colitis (UC) are classified as inflammatory bowel diseases (IBD). Currently, an increasing number of studies indicate that the metabolic consequences of IBD may include abnormalities in the fatty acid profile. The aim of this study was to compare fatty acid concentrations in IBD in order to identify differences between CD and UC and differences between the phases of both diseases. Methods: Sixty-three adolescent patients with CD (n = 33) and UC (n = 30) aged 13.66 ± 2.67 and 14.15 ± 3.31, respectively, were enrolled in the study. Analysis was performed by gas chromatography. Results: A statistically significant higher concentration of vaccenic acid was observed in the total UC group relative to total CD. In remission CD relative to active CD, a significantly higher concentration of palmitic acid was shown. Whereas in active CD, significantly higher levels of linoleic acid were observed relative to remission. The UC group had significantly higher lauric acid and gamma-linoleic acid levels in active disease relative to remission. Conclusions: The identified differences between FA levels in UC and CD could potentially be involved in the course of both diseases.

The role of fatty acids in Crohn's disease pathophysiology - An overview

Crohn's disease (CD) is an inflammatory bowel disease (IBD) which is characterized by chronic and relapsing inflammation of the gastrointestinal (GI) tract. The etiology of CD is unknown, but factors such as epithelial barrier dysfunction, immune system imbalance, microbiota dysbiosis and environmental influences are thought to be involved in its pathogenesis. Recent studies have shown that short chain fatty acids (SCFAs) and long chain fatty acids (LCFAs) play a vital role in pathophysiology and development of CD by various mechanisms affecting pro- and anti-inflammatory mediators, and maintaining the intestinal homeostasis and regulation of gene expression. SCFAs and LCFAs activate signaling cascades that control immune functions through interaction with cell surface free fatty acid receptors (FFARs), i.e. FFAR1, FFAR2, FFAR3, and FFAR4. This review highlights the role of fatty acids in maintenance of intestinal and immune homeostasis and supports the supplementation of fatty acids as a promising adjunctive treatment for CD.

Differential effects of EPA and DHA on DSS-induced colitis in mice and possible mechanisms involved

BACKGROUND

The anti-inflammatory effect of n-3 PUFAs has been widely documented. Emerging evidence suggests that the main component of n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may have differential effects in ulcerative colitis (UC). It was aimed to clarify their differential effects in UC.

METHODS

Eight-week-old male C57BL/6J mice were randomly divided into 7 groups, namely control, UC model, salicylazosulfapyridine (SASP), low-dose DHA, high-dose DHA, low-dose EPA, and high-dose EPA. DHA, EPA and SASP treatment groups were orally treated accordingly for 9 weeks. During the 5th to 9th week the control group was given distilled water, while other groups were given distilled water with 2% dextran sodium sulfate (DSS) to induce UC. Body weight loss, diarrhea, and stool bleeding were recorded to calculate the disease activity index (DAI). The level of tight junction proteins Claudin-1 and Occludin, and cytokines including TNF-α, IL-6, and IL-1β as well as inflammatory cell markers such as MPO, F4/80, and MCP-1 in the intestinal epithelium were measured using western blotting. Activation of IL-6/STAT3 and NLRP3/IL-1β inflammatory pathways was also assessed. Levels of proliferation-related proteins of the Wnt/β-catenin pathway with c-myc, Cyclin-D1, and PCNA were detected.

RESULTS

EPA, superior to DHA, significantly attenuated DSS-induced colitis evidenced by reduced DAI scores, cytokine production and inflammatory cell infiltration. Mechanically, EPA triggered a marked up-regulation of Claudin-1 and Occludin with down-regulation of their up-stream Akt and ERK. EPA also inhibited NLRP3/IL-1β and IL-6/STAT3 inflammatory pathways and up-regulated the Wnt/β-catenin pathway.

CONCLUSIONS

EPA is more suitable to be used for the treatment of UC than DHA.

Serum Polyunsaturated Fatty Acids Correlate with Serum Cytokines and Clinical Disease Activity in Crohn's Disease

Crohn’s disease (CD) has been associated with an increased consumption of n-6 polyunsaturated fatty acid (PUFA), while greater intake of n-3 PUFA has been associated with a reduced risk. We sought to investigate serum fatty acid composition in CD, and associations of fatty acids with disease activity, cytokines, and adipokines. Serum was prospectively collected from 116 CD subjects and 27 non-IBD controls. Clinical disease activity was assessed by the Harvey Bradshaw Index (HBI). Serum fatty acids were measured by gas chromatography. Serum cytokines and adipokines were measured by Luminex assay. Dietary histories were obtained from a subset of patients. Nine serum cytokines and adipokines were increased in CD versus controls. CD subjects had increased percentage serum monounsaturated fatty acids (MUFA), dihomo-gamma linolenic acid (DGLA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and oleic acid, but decreased arachidonic acid (AA) versus controls. The % total n-3 fatty acids and % EPA directly correlated with pro-inflammatory cytokine levels and HBI, whereas the % total n-6 fatty acids were inversely correlated with pro-inflammatory cytokine levels and HBI. CD subjects had increased caloric intake versus controls, but no alterations in total fat or PUFA intake. We found differences in serum fatty acids, most notably PUFA, in CD that correlated both with clinical disease activity and inflammatory cytokines. Our findings indicate that altered fatty acid metabolism or utilization is present in CD and is related to disease activity.

Effects of arachidonic acid intake on inflammatory reactions in dextran sodium sulphate-induced colitis in rats

The aim of this study was to investigate the effects of the administration of oral arachidonic acid (AA) in rats with or without dextran sulphate sodium (DSS)-induced inflammatory bowel disease. Male Wistar rats were administered AA at 0, 5, 35 or 240 mg/kg daily by gavage for 8 weeks. Inflammatory bowel disease was induced by replacing drinking water with 3 % DSS solution during the last 7 d of the AA dosing period. These animals passed loose stools, diarrhoea and red-stained faeces. Cyclo-oxygenase-2 concentration and myeloperoxidase activity in the colonic tissue were significantly increased in the animals given AA at 240 mg/kg compared with the animals given AA at 0 mg/kg. Thromboxane B2 concentration in the medium of cultured colonic mucosae isolated from these groups was found to be dose-dependently increased by AA, and the increase was significant at 35 and 240 mg/kg. Leukotriene B4 concentration was also significantly increased and saturated at 5 mg/kg. In addition, AA at 240 mg/kg promoted DSS-induced colonic mucosal oedema with macrophage infiltration. In contrast, administration of AA for 8 weeks, even at 240 mg/kg, showed no effects on the normal rats. These results suggest that in rats with bowel disease AA metabolism is affected by oral AA, even at 5 mg/kg per d, and that excessive AA may aggravate inflammation, whereas AA shows no effects in rats without inflammatory bowel disease.

Is there a role for fish oil in inflammatory bowel disease?

A number of animal and human studies suggest omega 3-fatty acids are anti-inflammatory. As a result they may have a therapeutic role in inflammatory bowel disease (IBD). The aim of this review is to briefly assess the literature about the utility of poly-unsaturated fatty acids (PUFAs) in the management of IBD. Taken together, almost all studies suggest some beneficial effects of n-3 PUFAs in IBD but the mechanism remains controversial. In addition, clinical benefit seems to be largely confined to ulcerative colitis. However all studies have concluded that these compounds have no potential for a steroid/aminosalicylic acid sparing effect or to maintain remission. Now the question arises as to whether this treatment is of real value to IBD patients? Clearly they have some therapeutic potential but further work is needed.

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.

Omega-3 fatty acids and inflammatory bowel diseases - a systematic review

BACKGROUND & AIM

Despite their well known anti-inflammatory actions, the clinical usefulness of omega-3 PUFA in inflammatory bowel disease is controversial. We aimed to systematically review the available data on the performance of omega-3 PUFA as therapeutic agents in these patients.

METHODS

Electronic databases were systematically searched for RCT of fish oil or omega-3 PUFA therapy in both active and inactive ulcerative colitis or Crohn's disease, without limitation on either the length of therapy or the form it was given, including nutritional supplements and enteral formula diets. Eligible articles were assessed for methodological quality on the basis of the adequacy of the randomisation process, concealment of allocation, blinding of intervention and outcome, possible biases, and completeness of follow-up. The five-point Oxford quality score was calculated.

RESULTS

A total of 19 RCT were finally selected for this review. Overall, available data do not allow to support the use of omega-3 PUFA supplementation for the treatment of both active and inactive inflammatory bowel disease. Negative results are quite consistent in trials assessing the use of omega-3 PUFA to maintain disease remission, particularly ulcerative colitis, and to a lesser extent Crohn's disease. Trials on their use in active disease do not allow to draw firm conclusions mainly because the heterogeneity of design (ulcerative colitis) or their short number (Crohn's disease). In most trials, the appropriateness of the selected placebo is questionable.

CONCLUSION

The present systematic review does not allow to make firm recommendations about the usefulness of omega-3 PUFA in inflammatory bowel disease.

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.

Combining nutrition, food science and engineering in developing solutions to Inflammatory bowel diseases--omega-3 polyunsaturated fatty acids as an example

The Inflammatory bowel diseases, Crohn's disease and ulcerative colitis, are debilitating conditions, characterised by lifelong sensitivity to certain foods, and often a need for surgery and life-long medication. The anti-inflammatory effects of long chain omega-3 polyunsaturated acids justify their inclusion in enteral nutrition formulas that have been associated with disease remission. However, there have been variable data in clinical trials to test supplementary omega-3 polyunsaturated fatty acids in inducing or maintaining remission in these diseases. Although variability in trial design has been suggested as a major factor, we suggest that variability in processing and presentation of the products may be equally or more important. The nature of the source, and rapidity of getting the fish or other food source to processing or to market, will affect the percentage of the various fatty acids, possible presence of heavy metal contaminants and oxidation status of the various fatty acids. For dietary supplements or fortified foods, whether the product is encapsulated or not, whether storage is under nitrogen or not, and length of time between harvest, processing and marketing will again profoundly affect the properties of the final product. Clinical trials to test efficacy of these products in IBD to date have utilised the relevant skills of pharmacology and gastroenterology. We suggest that knowledge from food science, nutrition and engineering will be essential to establish the true role of this important group of compounds in these diseases.

Cox-2 expression, PGE(2) and cytokines production are inhibited by endogenously synthesized n-3 PUFAs in inflamed colon of fat-1 mice

There is great interest in the role of polyunsaturated fatty acids (PUFAs) in promoting (n-6 class) or inhibiting (n-3 class) inflammation. Mammalian cells are devoid of desaturase that converts n-6 to n-3 PUFAs. Consequently, essential n-3 fatty acids must be supplied with the diet. We have studied the effect of endogenously produced n-3 PUFAs on colitis development in fat-1 transgenic mice carrying the Caenorhabditis elegans fat-1 gene encoding n-3 desaturase. Colonic cell lipid profile was measured by capillary gas chromatography in fat-1 and wild-type (WT) littermates fed standard diet supplemented with 10% (w/w) safflower oil rich (76%) in n-6 polyunsaturated linoleic acid (LA). Experimental colitis was induced by administrating 3% dextran sodium sulphate (DSS). Colitis was scored by histopatological analysis. Cyclooxygenase-2 (Cox-2) expression was evaluated by real time polymerase chain reaction. Prostaglandin E(2) (PGE(2)) levels and cytokine production were determined by enzyme and microsphere-based immunoassays, respectively. The n-6/n-3 PUFA ratios in colonic cells of fat-1 mice were markedly lower (9.83±2.62) compared to WT (54.5±9.24, P<.001). Results also showed an attenuation of colonic acute and chronic inflammation in fat-1 mice with significant decreases in PGE(2) production (P<.01) and Cox-2 expression (P<.01). High levels of colitis-induced proinflammatory cytokines, interleukin (IL)-18, IL-1α, IL-1β, IL-6, monocytes chemotactic proteins 1, 2 and 3 (MCP 1,2,3), matrix metalloproteinase 9 and tumor necrosis factor α (TNF-α) were down-regulated in DSS acutely and chronically treated fat-1 mice. The expression of fat-1 gene in the colon was associated with endogenous n-3 PUFAs production, decreased Cox-2 expression, increased PGE(2) and cytokine production.

Soybean and fish oil mixture increases IL-10, protects against DNA damage and decreases colonic inflammation in rats with dextran sulfate sodium (DSS) colitis

It was investigated whether dietary polyunsaturated fatty acids (PUFA) could influence colonic injury, tissue DNA damage, cytokines and myeloperoxidase activity (MPO) and plasma corticosterone in DSS-induced colitis rats. Male weaning Wistar rats were fed for 47 days with an AIN-93 diet with control (C), fish (F) or a mixture of fish and soybean oil (SF). The colitis was induced from day 36 until day 42 by 3% DSS in drinking water. On day 48, blood samples were collected for corticosterone determination. The distal colon was excised for histological analysis and to quantify the cytokine (IL-4, IL-10 and INF-γ), MPO and DNA damage. The disease activity index (DAI) was recorded daily during colitis induction. The DAI, MPO, histological analyses showed decreases only in the SF group compared with the C group. IL-10 was increased and DNA damage was reduced in the groups F and SF, and an inverse correlation between these variables was found. There were no differences in corticosterone, IFN-γ and IL-4 levels. Soybean and fish oil mixture may be effective in improving colonic injury and DNA damage, and it could be an important complementary therapy in UC to reduce the use of anti-inflammatory drugs and prevent colorectal cancer.

Plasma lipids and inflammation in active inflammatory bowel diseases

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) can cause metabolic and inflammatory alterations.

AIM

To evaluate the relationships between inflammatory parameters, plasma lipids and phospholipid fatty acid (FA) composition in patients with active UC and CD.

METHODS

Diet, the Harvey-Bradshaw Activity Index (HBAI), inflammatory parameters, lipoproteins and FA composition were assessed in 60 CD and 34 UC.

RESULTS

No differences in clinical parameters were observed in the two groups. Total cholesterol correlated inversely with the number of bowel movements in both groups and directly with BMI in UC. Arachidonic acid correlated inversely with HBAI in UC and total and HDL cholesterol were inversely related to C-reactive protein (CRP) in CD while HDL correlated with CRP in UC. Docosapentaenoic acid was the only polyunsaturated n-3 FA that was correlated to CRP in both groups. Total cholesterol was independently associated in the multiple regression analysis with the number of bowel movements and systemic inflammation.

CONCLUSIONS

Total and LDL cholesterol were lower in the active UC and CD than in the healthy subjects and were correlated with the systemic inflammatory status. Phospholipid FA composition was correlated to the systemic inflammatory status, but was unrelated to dietary intake and intestinal disease activity.

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.