Long-term intake of dietary fat and risk of ulcerative colitis and Crohn's disease

The role of a plant-based diet in the pathogenesis, etiology and management of the inflammatory bowel diseases

Introduction: Inflammatory Bowel Disease (IBD) carries a significant burden on an individual's quality-of-life and on the healthcare system. The majority of patients use dietary modifications to manage their symptoms, despite limited research to support these changes. There is emerging data that a plant-based diet will be of benefit to IBD patients.Areas covered: A literature review on the pathogenesis and potential benefits of dietary management of IBD.Expert opinion: A Westernized diet has been associated with IBD risk and relapse; hence a plant-based diet may be of benefit to IBD patients through reducing inflammation and restoring symbiosis. Dietary therapy can be an important adjunct therapy, however, better quality studies are still required.

The Influence of Nutrients on Inflammatory Bowel Diseases

Inflammatory bowel diseases is a group of inflammatory diseases. The pathogenesis of diseases is multifactorial, which may include a Western-type diet. Diseases occur with periods of recurrence and remission. Many factors can have a beneficial effect on reducing the frequency of recurrence and prolonging the remission period. Such ingredients include dietary fibre, mono- and polyunsaturated fatty acids, certain vitamins (D, C, and E), flavonoids, and minerals such as zinc and selenium. Properly selected nutrition might be an integral part of the treatment of patients with Crohn's disease or ulcerative colitis.

Allergic and Immunologic Perspectives of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammatory condition primarily involving the gastrointestinal tract. It includes Crohn's disease (CD), ulcerative colitis (UC), and a less common phenotype-indeterminate colitis. It is thought to result from a complex interplay of environmental, microbial, and host factors including genetic factors, although the exact mechanism is not known. Dietary factors have been shown to play a role in the pathogenesis of IBD and can potentially alter the intestinal microbiota as well as disrupt the immune function in the gut. CD is characterized by transmural inflammation, sometimes associated with granulomatous lesions, and involves the entire gastrointestinal tract but often spares the rectum. UC is characterized by mucosal inflammation typically confined to the colon and rectum. Although IBD is mostly seen in western world, recent data suggests that the incidence and prevalence are increasing worldwide. Enteral nutrition has been shown to be effective in inducing remission in pediatric population with CD; however, there is mixed data in adult population. Nutritional deficiencies such as vitamin D and zinc deficiency are often noted in IBD patients. Several extraintestinal manifestations are noted in patients with IBD. Some of them parallel with the disease activity and others are independent of the disease course. Assessment of IBD disease activity clinically, radiologically, if indicated, biochemically and endoscopically is important to guide therapy in IBD. To ensure comprehensive care, it is important to assess associated conditions such as nutritional and psychological well-being, as well as age appropriate health maintenance status prior to starting treatment for IBD. Several biologic agents including anti-tumor necrosis factor alpha (anti-TNF-α) drugs, anti-integrins, and antibodies to the p40 subunit of IL12/23 are approved for induction and maintenance of remission of IBD. Steroids are also often used for induction. Anti-metabolites and thiopurines are also useful either as monotherapy or in combination regimens. Potential side effects of anti-TNF-α drugs such as serious infections, malignancy, worsening of heart failure, and infusion-related reactions should be considered prior to starting these drugs. Anti-TNF-α drugs with or without immunomodulators (azathioprine, 6-mercaptopurine, methotrexate) are often used for the induction and maintenance of remission. Treating to target of endoscopic and clinical remission provides the best long-term outcomes. Our knowledge and understanding of IBD has grown significantly. However, there are several unanswered questions on pathogenesis, disease behavior, and drivers of inflammation in various patient subgroups which require further research.

A diet based on cured acorn-fed ham with oleic acid content promotes anti-inflammatory gut microbiota and prevents ulcerative colitis in an animal model

Background

Diets based on meat products are not recommended in the case of ulcerative colitis (UC). The objective here is to test if some traditional cured meat products, as acorn-fed ham (high levels of oleic acid), may be useful for controlling inflammatory diseases as UC in animal models, which could represent a new dietary complementary intervention in the prevention of this inflammatory disease in humans.

Methods

Two rat cohorts have been used: conventional vegetable rat feed and acorn-fed ham. UC was induced with DSS in drinking water ad libitum for 1 week. Short-chain fatty acids (SCFAs) and 16S rRNA metagenomics from bacterial populations were analyzed in cecum samples. Colon samples were analyzed for histological parameters.

Results

Acorn-fed ham diet induced changes in gut microbiota composition, with pronounced enrichments in anti-inflammatory bacterial genera (Alistipes, Blautia, Dorea, Parabacteroides). The animals with this diet showed a strong reduction in most parameters associated to ulcerative colitis: disease activity index, macroscopic score of colitis, epitelium alteration in colon mucosa, inflammatory cell density in colon, myeloperoxidase titers in colon, proinflammatory cytokines (IL-17, IFN-γ). Also, acorn-fed ham diet animals showed increased total antioxidant activity an oleic acid levels in plasma, as well as higher short-chain fatty acid concentrations in cecum (isobutyric, isovaleric and valeric).

Conclusions

In the acorn-fed ham cohort, as a result of the dietary intake of oleic acid and low intake of omega-6 fatty acids, a strong preventive effect against UC symptoms was observed.

Evaluation of nutritional adequacy in adult patients with Crohn's disease: a cross-sectional study

Purpose

Inadequate oral intake may play an important role in the onset of malnutrition in patients with Crohn’s disease (CD). The aims of this cross-sectional study were: (1) to compare dietary intake in clinically active and quiescent CD patients, and (2) to assess patients’ nutritional adequacy relative to the dietary reference values (DRVs) for the Italian population using LARN (Livelli di Assunzione di Riferimento di Nutrienti ed energia per la popolazione italiana).

Methods

Patients aged between 18 and 65 years with a diagnosis of CD were recruited. All participants underwent anthropometry and were instructed to fill in a 3-day food record. Disease activity was clinically defined using the Crohn’s disease activity index (CDAI).

Results

Overall, 117 patients, 71 males and 46 females, with a mean age of 39.6 ± 13.8 years and a mean body weight of 65.4 ± 11.8 kg, were ultimately included. Our findings showed that the amount of nutrients was similar between patients with active and quiescent disease. The mean intake of macronutrients was adequate, except for fiber, while dietary micronutrients were insufficient. Median intakes of sodium, phosphorus, and fluorine met LARN recommendations in both sexes, and the DRVs were accomplished by many patients (53/117; 104/117 and 98/117, respectively). Interestingly, dietary amounts of iron and zinc were barely acceptable in males but not in females. However, a few of the patients (< 15) met the LARN for potassium, calcium, and magnesium, regardless of sex and CDAI. With respect to vitamins, no relevant difference was found between the active and quiescent groups, and none of them met recommended values in both sexes.

Conclusions

This study showed that the assessment of dietary intake can be crucial for optimizing dietary intervention with focused nutrition counseling, to improve nutritional status in CD patients.

NCoR1 Protects Mice From Dextran Sodium Sulfate-Induced Colitis by Guarding Colonic Crypt Cells From Luminal Insult

BACKGROUND & AIMS

Colonic stem cells are essential for producing the mucosal lining, which in turn protects stem cells from insult by luminal factors. Discovery of genetic and biochemical events that control stem cell proliferation and differentiation can be leveraged to decipher the causal factors of ulcerative colitis and aid the development of more effective therapy.

METHODS

We performed in vivo and in vitro studies from control (nuclear receptor corepressor 1 [NCoR1^F/F]) and intestinal epithelial cell-specific NCoR1-deficient mice (NCoR1^ΔIEC). Mice were challenged with dextran sodium sulfate to induce experimental ulcerative colitis, followed by colitis examination, barrier permeability analysis, cell proliferation immunostaining assays, and RNA sequencing analysis. By using crypt cultures, the organoid-forming efficiency, cell proliferation, apoptosis, and histone acetylation were analyzed after butyrate and/or tumor necrosis factor α treatments.

RESULTS

NCoR1^ΔIEC mice showed a dramatic increase in disease severity in this colitis model, with suppression of proliferative cells at the crypt base as an early event and a concomitant increase in barrier permeability. Genome expression patterns showed an important role for NCoR1 in colonic stem cell proliferation and secretory cell differentiation. Colonic organoids cultured from NCoR1^ΔIEC mice were more sensitive to butyrate-induced cell growth inhibition and apoptosis, which were exaggerated further by tumor necrosis factor α co-treatment, which was accompanied by increased histone acetylation.

CONCLUSIONS

NCoR1 regulates colonic stem cell proliferation and secretory cell differentiation. When NCoR1 is disrupted, barrier protection is weakened, allowing luminal products such as butyrate to penetrate and synergistically damage the colonic crypt cells. Transcript profiling: RNA sequencing data have been deposited in the GEO database, accession number: GSE136153.

Crohn's disease and ulcerative colitis are associated with different lipid profile disorders: a nationwide population-based study

BACKGROUND

The relationships between lipid profiles and IBD remain elusive.

AIM

To determine the association of IBD with serum lipid profiles.

METHODS

A nationwide population-based study was performed using claims data from the Korean National Healthcare Insurance service. A total of 9 706 026 subjects undergoing medical check-ups in 2009 were enrolled and followed up until 2016. Individuals who developed Crohn's disease (CD) or ulcerative colitis (UC) were identified during follow-up. Adjusted hazard ratio (aHR) by age, sex, body mass index, cigarette smoking, alcohol drinking, exercise, income and underlying comorbidities was calculated to define the impact of serum lipid profiles on developing IBD.

RESULTS

During a median follow-up of 7.3 years, IBD was detected in 7,058 (0.07%) individuals. Compared with the highest quartile of serum total cholesterol (TC) levels, lower TC levels were associated with higher incidence of CD (aHR: Q1, 2.52; Q2, 1.52; Q3, 1.27), but not UC. Lower serum LDL-C levels were associated with higher incidence of CD (aHR: Q1, 1.92; Q2, 1.47; Q3, 1.22), but not UC. Moreover, lower serum HDL-C levels were associated with higher incidence of CD (aHR: Q1, 2.49; Q2, 1.90; Q3, 1.43), but not UC. In contrast, lower serum triglyceride levels were associated with higher incidence of UC (aHR: Q1, 1.22; Q2, 1.19; Q3, 1.19), but not CD.

CONCLUSIONS

Low serum TC, LDL-C and HDL-C levels were associated with CD. Low serum triglyceride levels were related to UC.

"Diet in the Etiopathogenesis of IBD: Is There A Culinary Culprit?"

Research suggests that diet plays a role in the development of inflammatory bowel disease (IBD). Eating more fiber, omega-3 fatty acids, and limiting food additives may lower risk. More research is needed to better understand diet factors that may protect against IBD.

Impact of Diet on Risk of IBD

Diet is an important factor influencing the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC). Several recent prospective cohorts have suggested various dietary factors may play a role in modifying the risk of these diseases. These include an inverse association between dietary fiber, fruit or vegetable intake and risk of CD and n-3 polyunsaturated fatty acids and UC. In addition to macro-nutrients, dietary additives such as emulsifiers may also play a role.

ESPEN practical guideline: Clinical Nutrition in inflammatory bowel disease

The present guideline is the first of a new series of "practical guidelines" based on more detailed scientific guidelines produced by ESPEN during the last few years. The guidelines have been shortened and now include flow charts that connect the individual recommendations to logical care pathways and allow rapid navigation through the guideline. The purpose of the present practical guideline is to provide an easy-to-use tool to guide nutritional support and primary nutritional therapy in inflammatory bowel disease (IBD). The guideline is aimed at professionals working in clinical practice, either in hospitals or in outpatient medicine, and treating patients with IBD. In 40 recommendations, general aspects of care in patients with IBD, and specific aspects during active disease and in remission are addressed. All recommendations are equipped with evidence grades, consensus rates, short commentaries and links to cited literature.

Dining With Inflammatory Bowel Disease: A Review of the Literature on Diet in the Pathogenesis and Management of IBD

Inflammatory bowel diseases (IBDs) are chronic immune-related diseases hypothesized to be a sequela of an interplay of genetic predisposition and environmental exposures. The global incidence of IBD is increasing, and more patients are exploring diet as a means to explain and treat their IBD. In fact, many patients strongly believe diet plays a fundamental role in the onset and management of their IBD. However, a significant proportion of patients report limited nutritional education from their provider, and providers report limited nutritional resources to aid in discussions with patients. This imbalance between supply and demand likely reflects the previous paucity of available literature characterizing the influence of diet in IBD. To address this gap in knowledge, we review the available literature to characterize the role of diet in the pathogenesis, exacerbation, and treatment of IBD. We aim to provide patients and providers with resources to better understand and discuss the role of diet in IBD, with the overall goal of improving patient care and satisfaction.

Efficacy of enteral nutrition in patients with Crohn's disease on maintenance anti-TNF-alpha antibody therapy: a meta-analysis

Enteral nutrition (EN) is effective in Crohn's disease (CD) patients and has been shown to have an inhibitory effect on loss of response to anti-tumor necrosis factor (TNF)-alpha antibody therapy; however, the current level of evidence is not sufficient. The objective of this meta-analysis was to determine whether EN in combination anti-TNF-alpha antibody therapy is useful in maintaining remission. PubMed was used to identify all relevant studies. A total of nine articles were identified including one randomized control trial, two prospective cohort studies, and six retrospective cohort studies. We performed a meta-analysis on all these articles to assess the remission maintenance effect of EN (n = 857). The remission or response maintenance effect in the EN group was 203/288 (70.5%), which was higher than 306/569 (53.8%) in the non-EN group. The odds ratio for long-term remission or response using fixed effects model and random effects model were 2.23 (95% CI 1.60-3.10) and 2.19 (95% CI 1.49-3.22), respectively. The usefulness of EN was unclear in two prospective studies that were conducted immediately after remission induction with anti-TNF-alpha antibody therapy was detected. Differences in the definition of relapse and the observation period among articles were considered to be limitations. This analysis suggests that EN is effective for maintaining remission in patients already in remission or response as a result of anti-TNF-alpha antibody maintenance therapy.

Genetic polymorphisms of ATG16L1 and IRGM genes in Malaysian patients with Crohn's disease

OBJECTIVE

To investigate the association between genetic polymorphisms in ATG16L1 and IRGM genes and the development of Crohn's disease (CD) in Malaysian patients.

METHODS

Altogether 335 participants were recruited, including 85 patients with CD and 250 unrelated healthy controls, and their informed consent was obtained. Genomic DNA was extracted via a conventional phenol-chloroform extraction method. Six single nucleotide polymorphisms (SNPs) in ATG16L1 and IRGM genes were genotyped using TaqMan SNP genotyping assays. Associations between SNP and CD were determined using Fisher's exact test, odds ratio, and 95% confidence interval. Statistical power and the Hardy-Weinberg equilibrium were also calculated.

RESULTS

Two SNPs (rs2241880 and rs6754677) in the ATG16L1 gene were significantly associated with the onset of CD in the Malaysian population. The A allele and homozygous A/A genotype of the rs2241880 A/G polymorphism were protective against CD in the overall Malaysian and Malay population. The G allele and homozygous G/G genotype of the rs6754677 G/A polymorphism were protective in the Indian population, whereas the homozygous A/A genotype showed a risk of developing CD. The homozygous G/G genotype of IRGM rs11747270 was significantly present in the controls. However, this significance was not observed in a race-stratified analysis. All three ATG16L1 SNPs were associated with inflamed terminal ileum. IRGM rs4958847 and rs11747270 increased the risk of developing arthritis in patients with CD.

CONCLUSION

We found a significant association between SNP, which are located in autophagy-related genes, and CD in a Malaysian population.

Protection by pure and genistein fortified extra virgin olive oil, canola oil, and rice bran oil against acetic acid-induced ulcerative colitis in rats

Conjugation of genistein and dietary oils improves the anti-inflammatory and antioxidant effects of genistein on colitis in rats.

High-fat diet-derived free fatty acids impair the intestinal immune system and increase sensitivity to intestinal epithelial damage

In Japan and other Asian countries, increased fat uptake induced by a westernized diet is thought to be associated with an increased incidence of inflammatory bowel disease, colorectal cancer and food allergies; however, the mechanism for this remains unclear. High-fat diet (HFD)-fed mice are common animal models used to examine the effect of fat intake in vivo. HFDs are reported to exacerbate DSS-induced colitis and intestinal tumorigenesis, but the effect of HFDs on the intestines before disease induction is often overlooked. We found that the intestinal and gut-associated lymphoid tissue (GALT) morphology of HFD-fed mice differed from that of standard diet (SD)-fed mice. To clarify the mechanism by which fat intake increases intestinal diseases, we analyzed the morphological and immunological aspects of the intestines of HFD-fed mice as well as the molecular mechanisms and physiology. Feeding an HFD for 3 weeks induced atrophy of the small intestine, colon and GALT and reduced the number of small intestinal intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs). Feeding an HFD for only one day reduced the number of small intestinal (SI)-IELs and SI-LPLs. The effect of feeding a 3-week HFD continued for 2 weeks after returning to the SD. The effect of the HFD on the intestinal immune system was independent of the gut microbes. We hypothesized that the cytotoxicity of the abundant HFD-derived free fatty acids in the intestinal lumen impairs the intestinal immune system. Both saturated and unsaturated free fatty acids were toxic to intestinal T-cells in vitro. Orally administering free fatty acids reduced the number of SI-IELs and LPLs. Using a lipase inhibitor to reduce the luminal free fatty acids attenuated the HFD-induced changes in the intestinal immune system, while using a statin to reduce the serum free fatty acids did not. Thus, HFD-induced free fatty acids damaged the intestines; this effect was termed "intestinal lipotoxicity". Because sustained reduction of SI-LPLs after HFD feeding exacerbated indomethacin-induced small intestinal damage, lipotoxicity to the human intestines incurred by consuming a westernized diet in Japan may increase intestinal diseases such as IBD, colorectal cancer or food allergies.

Dietary total antioxidant capacity and risk of ulcerative colitis: A case-control study

OBJECTIVE

Data on the association between the antioxidant capacity of a diet and the risk of ulcerative colitis (UC) are scarce. This study aimed to assess whether a relationship exists between dietary total antioxidant capacity (TAC) and the odds of UC in Iranian adults.

METHODS

In this case-control study, patients with UC and age-matched healthy controls were recruited from a hospital clinic. All participants completed a validated 168-item food frequency questionnaire, the results of which were subsequently used to generate dietary TAC. Ferric reducing-antioxidant power values were used to calculate dietary TAC.

RESULTS

Altogether 62 patients with UC and 124 healthy controls were enrolled. UC patients had a higher calorific intake (P < 0.01), and consumed more monounsaturated fatty acids (P < 0.01), vitamin B9 (P < 0.01) and calcium (P = 0.02) compared with healthy controls, while the control group had a higher vitamin C intake than the participants with UC (P < 0.01). In a fully adjusted model, participants who were in the highest quartile of dietary TAC had a lower risk of UC (odds ratio 0.11, 95% confidence interval 0.01-0.73).

CONCLUSIONS

A higher dietary TAC score was associated with lower odds of UC in this case-control study. Further elucidation of the role of key dietary elements is now warranted.

Effects of One Year of Vitamin D and Marine Omega-3 Fatty Acid Supplementation on Biomarkers of Systemic Inflammation in Older US Adults

BACKGROUND

Observational studies suggest vitamin D and marine ω-3 fatty acid (n-3 FA) supplements are associated with lower systemic inflammation. However, past trials have been inconsistent.

METHODS

The randomized, double-blind, placebo-controlled VITamin D and OmegA-3 TriaL (VITAL) tested vitamin D (2000 IU/day) and/or n-3 FA (1 g/day) supplementation in a 2 × 2 factorial design among women ≥55 and men ≥50 years of age. We assessed changes in interleukin (IL)-6, tumor necrosis factor receptor 2 (TNFR2), and high-sensitivity C-reactive protein (hsCRP) concentrations from baseline to 1 year among participants randomized to vitamin D + n-3 FA (392), vitamin D (392), n-3 FA (392), or placebo only (385). Geometric means and percent changes were compared, adjusting for baseline factors.

RESULTS

Baseline characteristics were well balanced. In the active arms, 25-OH vitamin D rose 39% and n-3 FA rose 55% vs minimal change in placebo arms. Neither supplement reduced biomarkers at 1 year. Vitamin D resulted in 8.2% higher IL-6 (95% CI, 1.5%-15.3%; adjusted P = 0.02), but TNFR2 and hsCRP did not. Among 784 receiving vitamin D, hsCRP increased 35.7% (7.8%-70.9%) in those with low (<20 ng/mL) but not with higher baseline serum 25(OH) vitamin D [0.45% (-8.9% to 10.8%); P interaction = 0.02]. Among 777 randomized to n-3 FA, hsCRP declined [-10.5% (-20.4% to 0.8%)] in those with baseline low (<1.5 servings/week), but not with higher fish intake [6.4% (95% CI, -7.11% to 21.8%); P interaction = 0.06].

CONCLUSIONS

In this large sample from a population-based randomized controlled trial, neither vitamin D nor n-3 FA supplementation over 1 year decreased these biomarkers of inflammation.

CLINICALTRIALSGOV IDENTIFIER

NCT01169259; NCT01351805.

Validity and reliability of Food-Mood Questionnaire (FMQ)

BACKGROUND

The need for short and validated questionnaires to evaluate dietary patterns (DPs) and mental distress in clinical and research settings is increasing.

AIM

The purpose of this study was to develop and validate a Food-Mood Questionnaire (FMQ) to assess DPs in relation to mental distress.

METHOD

A standard validation protocol that included item development, pilot-testing, test-retesting, and a series of statistical validation analyses was used. Content, face, internal, construct and external validity as well as reliability were confirmed. Content and face validity were evaluated qualitatively.

RESULTS

Principal component analysis (PCA) for construct validity generated five sub-scales which reflected internal consistency (Cronbach's α > 0.70) and internal reliability (intraclass correlation coefficient ranged between 0.619 and 0.884; p < 0.01; confidence interval 95%). External validity was also confirmed. A total of 563 participants from four different continents completed the survey online. PCA generated five different subscales. Mental distress was associated with regular consumption of fast-food, a DP known to induce anxiety and depression.

CONCLUSION

The FMQ is a validated and a reliable tool with many potential applications that could be used with prophylactic and therapeutic approaches.

Healthy Eating Index-2015 as a predictor of ulcerative colitis risk in a case-control cohort

OBJECTIVE

There is compelling clinical evidence implicating certain dietary components in the development and clinical course of progression in ulcerative colitis (UC). This study aimed to assess whether any association exists between ulcerative colitis and scores on a healthy eating index.

METHODS

In this case-control study patients with UC were recruited and assessed together with healthy controls. The participants completed a validated 168-item food frequency questionnaire, the results of which were subsequently used to generate individual healthy eating index (HEI-2015) scores.

RESULTS

Altogether 58 patients with UC and 123 healthy controls were recruited. After controlling for confounding factors, participants who were in the highest quartile of the HEI-2015 had a 66% lower odds ratio (OR) of UC than the lowest quartile (OR = 0.34, 95% confidence interval 0.12-0.96).

CONCLUSION

HEI-2015 was associated with UC in this cohort. Further elucidation of the role of key dietary elements is now warranted.

Immunological mechanisms underpinning faecal microbiota transplantation for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease that results from a dysregulated immune response against specific environmental triggers in a genetically predisposed individual. Increasing evidence has indicated a causal role for changes in gut microbiota (dysbiosis) contributing to this immune-mediated intestinal inflammation. These mechanisms involve dysregulation of multiple facets of the host immune pathways that are potentially reversible. Faecal microbiota transplantation (FMT) is the transfer of processed stool from a healthy donor into an individual with an illness. FMT has shown promising results in both animal model experiments and clinical studies in IBD in the resolution of intestinal inflammation. The underlying mechanisms, however, are unclear. Insights from these studies have shown interactions between modulation of dysbiosis via changes in abundances of specific members of the gut microbial community and changes in host immunological pathways. Unravelling these causal relationships has promising potential for a translational therapy role to develop targeted microbial therapies and understand the mechanisms that underpin IBD aetiopathogenesis. In this review, we discuss current evidence for the contribution of gut microbiota in the disruption of intestinal immune homeostasis and immunoregulatory mechanisms that are associated with the resolution of inflammation through FMT in IBD.

Nutritional interventions for the treatment of IBD: current evidence and controversies

Environmental factors, particularly diet, are the focus of current research as potential triggers of inflammatory bowel disease (IBD). Epidemiological cohort data showing a rapid increase of IBD in western countries and the emergence of IBD in developing countries paralleling the introduction of a western diet are indirect arguments linking food and food behaviour to intestinal inflammation. The successful use of exclusive enteral nutrition (EEN), now considered as first-line induction therapy for paediatric Crohn's disease (CD), is the strongest argument for a link between diet and IBD. Mechanistic studies revealed that EEN impacts intestinal microbiota composition and together with the exclusion of potentially harmful food ingredients this allows the control of intestinal inflammation and induces mucosal healing. However, the exclusivity character of EEN is a major drawback. Based on the data of EEN, the search for more tolerable and still effective diets has begun. Recent reports on the new CD exclusion diet (CDED), CD-TREAT, as well as the specific carbohydrate diet (SCD) provide the first promising results, further underlining the potential of diet to control inflammation in patients with CD by excluding certain food components. Ongoing research is trying to combine nutritional interventions with analyses of intestinal microbiota and their metabolic functions with the aim of correcting the intestinal dysbiosis that characterizes IBD. This research is promising and gives new hope to patients that have been looking for decades for nutritional interventions with the aim of stabilizing their disease course. There might even be potential for disease prevention in high-risk patients by excluding potentially harmful food components.

The Role of Long-Chain Fatty Acids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a complicated disease involving multiple pathogenic factors. The complex relationships between long-chain fatty acids (LCFAs) and the morbidity of IBD drive numerous studies to unravel the underlying mechanisms. A better understanding of the role of LCFAs in IBD will substitute or boost the current IBD therapies, thereby obtaining mucosal healing. In this review, we focused on the roles of LCFAs on the important links of inflammatory regulation in IBD, including in the pathogen recognition phase and in the inflammatory resolving phase, and the effects of LCFAs on immune cells in IBD.

Excess calorie intake early in life increases susceptibility to colitis in adulthood

Epidemiological data reveal an association between obesity and inflammatory bowel disease (IBD). Furthermore, animal models demonstrate that maternal high-fat diet (HFD) and maternal obesity increase susceptibility to IBD in offspring. Here we report that excess calorie intake by neonatal mice, as a consequence of maternal HFD, forced feeding of neonates or low litter competition, leads to an increase during weaning in intestinal permeability, expression of pro-inflammatory cytokines and hydrogen sulfide production by the microbiota. These intestinal changes engage in mutual positive feedback that imprints increased susceptibility to colitis in adults. The pathological imprinting is prevented by the neutralization of IFN-γ and TNF-α or the production of hydrogen sulfide, or by normalization of intestinal permeability during weaning. We propose that excess calorie intake by neonates leads to multiple causally linked perturbations in the intestine that imprint the individual with long-term susceptibility to IBD.

Nutritional approach as therapeutic manipulation in inflammatory bowel disease

Malnutrition is observed more frequently in patients with inflammatory bowel disease (IBD) than in the general population and associated with adverse clinical outcomes. This study aimed to review the current knowledge regarding the efficacy of dietary and nutritional intervention in IBD patients. Exclusive enteral nutrition might be inferior to corticosteroid treatment in adults with active Crohn’s disease (CD) but might even be superior considering the adverse effects of corticosteroid treatment in children. Total parenteral nutrition has no advantage over enteral nutrition, which is considered a more physiologic modality in organ function. Current guidelines do not yet recommend ω3-polyunsaturated fatty acid supplementation for the prevention and maintenance of remission in IBD patients. Dietary fiber supplementation could be effective in the relief of symptoms and maintenance of remission in ulcerative colitis (UC). Although vitamin D may be favorable to clinical course of IBD and bone density. Probiotic supplementation has proven to be effective in preventing and treating pouchitis for UC but is less effective in treating CD. Nutritional interventions not only correct nutritional deficiencies but also improve symptoms and clinical courses of the disease. Hence, nutritional approaches need to be developed to significantly evaluate the effectiveness of dietary interventions used to treat IBD.

Dietary fatty acid content influences the expression of genes involved in the lipid turnover and inflammation in mouse colon and spleen

BACKGROUND

Dietary interventions can improve gastrointestinal (GI) symptoms. We determined the effects of fatty acids (FAs) supplementation with medium- and long-chain saturated FAs on mouse GI motility and correlated them with the expression of genes for free FA receptors (FFAR)1-4, FA binding protein 4 (FABP4) and inflammation.

METHODS

Forty-eight BalbC were assigned to: standard diet (STD), diet rich in medium-chain saturated FAs (COCO) and long-chain saturated FAs (HF) (7% by weight). Body weight (BW) and food intake (FI) were monitored for 8-weeks. GI motility was determined by fecal pellet output (FPO) and colon bead expulsion tests. FABP4 inhibitor, BMS309403 (1mg/kg, ip) was injected to half of each group 2 days/week. mRNA expression of FABP4, (FFAR)1-4, and pro-inflammatory cytokines were measured in colonic and splenic tissues using real-time PCR.

RESULTS

COCO and HF decreased FI. COCO accelerated overall GI transit (p<0.05). COCO increased the mRNA expression of FFAR2 (p<0.001) and TNFα (p<0.01); HF increased the expression of FABP4 and FFAR4 (p<0.05), and FFAR2 (p<0.001) in the colon, and decreased FFAR1 and FFAR4 (p<0.001), TNFα (p<0.01) and IL-1β (p<0.05) in splenic tissues. BMS309403 decreased the FI and delayed colonic transit in STD+BMS and COCO+BMS vs. STD (p<0.05). HF+BMS increased colonic expression of FFAR3 (p<0.01), TNFα (p<0.01), IL-6 (p<0.01), and reduced FFAR4 (p<0.05); COCO+BMS decreased TNFα (p<0.01).

CONCLUSION

Diversification in the dietary lipid content affected GI motility in mice and the expression of FFARs and pro-inflammatory cytokines in vivo.

High-fat diet promotes experimental colitis by inducing oxidative stress in the colon

Diets high in animal fats are associated with increased risks of inflammatory bowel disease, but the mechanism remains unclear. In this study, we investigated the effect of high-fat diet (HFD) on the development of experimental colitis in mice. Relative to mice fed low-fat diet (LFD), HFD feeding for 4 wk increased the levels of triglyceride, cholesterol, and free fatty acids in the plasma as well as within the colonic mucosa. In an experimental colitis model induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS), mice on 4-wk HFD exhibited more severe colonic inflammation and developed more severe colitis compared with the LFD counterparts. HFD feeding resulted in higher production of mucosal pro-inflammatory cytokines, greater activation of the myosin light chain kinase (MLCK) tight junction regulatory pathway, and greater increases in mucosal barrier permeability in mice following TNBS induction. HFD feeding also induced gp91, an NADPH oxidase subunit, and promoted reactive oxygen species (ROS) production in both colonic epithelial cells and lamina propria cells. In HCT116 cell culture, palmitic acid or palmitic acid and TNF-α combination markedly increased ROS production and induced the MLCK pathway, and these effects were markedly diminished in the presence of a ROS scavenger. Taken together, these data suggest that HFD promotes colitis by aggravating mucosal oxidative stress, which rapidly drives mucosal inflammation and increases intestinal mucosal barrier permeability.NEW & NOTEWORTHY This study demonstrates high-fat diet feeding promotes colitis in a 2,4,6-trinitrobenzenesulfonic acid-induced experimental colitis model in mice. The underlying mechanism is that high-fat diet induces oxidative stress in the colonic mucosa, which increases colonic epithelial barrier permeability and drives colonic mucosal inflammation. These observations provide molecular evidence that diets high in saturated fats are detrimental to patients with inflammatory bowel diseases.

Impact of Food Additives on Gut Homeostasis

In physiological conditions, the gut is heavily infiltrated with various subsets of inflammatory cells, whose activity is tightly controlled by counter-regulatory mechanisms. Defects in such mechanisms can favour the development of chronic intestinal disorders, such as Crohn’s disease (CD) and ulcerative colitis (UC), the principal forms of inflammatory bowel diseases (IBD) in humans, as well as systemic disorders. Over the last years, the frequency of intestinal and systemic immune-inflammatory disorders has increased in previously low incidence areas, likely due to the Westernization of lifestyles, including dietary habits. The Western diet is characterized by high consumption of proteins, saturated fats and sweets, as well as by a broad use of food additives (e.g., emulsifiers, bulking agents), which are used to preserve and enhance food quality. Accumulating evidence suggests that food additives can perturb gut homeostasis, thereby contributing to promote tissue-damaging inflammatory responses. For instance, mice given the emulsifiers carboxymethylcellulose and polysorbate 80 develop dysbiosis with overgrowth of mucus-degrading bacteria. Such an effect triggers colitis in animals deficient in either interleukin-10, a cytokine exerting anti-inflammatory and regulatory functions, or Toll-like receptor 5, a receptor recognizing the bacterial flagellin. Similarly, the polysaccharide maltodextrin induces endoplasmic reticulum stress in intestinal goblet cells, thereby impairing mucus release and increasing host susceptibility to colitis. In this review, we report and discuss the current knowledge about the impact of food additives on gut homeostasis and their potential contribution to the development of inflammatory disorders.

An Autoimmune Protocol Diet Improves Patient-Reported Quality of Life in Inflammatory Bowel Disease

BACKGROUND

Prior studies suggest dietary modification may improve clinical response or remission rates in patients with inflammatory bowel disease (IBD). Our aim was to examine whether an autoimmune protocol diet improves quality of life in patients with active Crohn disease (CD) and ulcerative colitis (UC).

METHODS

We conducted an uncontrolled clinical trial of the autoimmune protocol diet in adult patients with active IBD (Harvey-Bradshaw Index ≥ 5 for CD or partial Mayo score ≥ 3 for UC, and erosions/ulcers on endoscopy and/or elevated fecal calprotectin). The dietary intervention consisted of a 6-week elimination phase, followed by a 5-week maintenance phase. Short Inflammatory Bowel Disease Questionnaire (SIBDQ) was completed at baseline, and weeks 3, 6, 9, and 11.

RESULTS

The final cohort included 6 UC and 9 CD participants. Mean SIBDQ score improved significantly from baseline (46.5) to weeks 3 (54.0, P = 0.02), 6 (53.3, P = 0.02), 9 (62.0, P = 0.03), and 11 (60.5, P = 0.05). Among participants completing all 5 surveys, mean SIBDQ increased from 46.5 to 61.5 by week 11 (P = 0.03). By week 3, participants experienced significant improvements in bowel movement frequency (36%, P = 0.04), stress (28%, P = 0.01), and ability to perform leisure/sport activities (29%, P = 0.02). Effects were not significantly different between CD and UC participants.

CONCLUSIONS

Dietary modification can improve quality of life as early as week 3 in patients with active IBD. Larger randomized controlled trials are needed to examine dietary interventions in IBD.

Omega Fatty Acids and Inflammatory Bowel Diseases: An Overview

Inflammatory bowel diseases (IBD) are chronic, inflammatory processes that affect the gastrointestinal tract and are mainly represented by ulcerative colitis (UC) and Crohn’s disease (CD). Omega 3 (ω3) fatty acids (eicosapentanoic acid and docosahexaenoic acid) show an indispensable role in the inflammatory processes and, for these reasons, we aimed to review the effects of these acids on UC and CD. Databases such as PUMED and EMBASE were searched, and the final selection included fifteen studies that fulfilled the inclusion criteria. The results showed that ω3 fatty acids reduce intestinal inflammation, induce and maintain clinical remission in UC patients, and are related with the reduction of proinflammatory cytokines, decrease disease activity and increase the quality of life of CD patients. Furthermore, the consumption of these fatty acids may be related to a reduced risk of developing IBD. Many studies have shown the beneficial effects of ω3 as adjunctive in the treatment or prevention of UC or CD. Nevertheless, most were performed with a small number of patients and there are many variations in the mode of consumption, the type of food or the type of formulation used. All these factors substantially interfere with the results and do not allow reliable comparisons.

Changes in the diet composition of fatty acids and fiber affect the lower gastrointestinal motility but have no impact on cardiovascular parameters: In vivo and in vitro studies

BACKGROUND

Food and diet are central issues for proper functioning of the cardiovascular (CV) system and gastrointestinal (GI) tract. We hypothesize that different types of dietary FAs affect CV parameters as well as GI motor function and visceral sensitivity.

METHODS

Male Wistar rats were fed with control diet (CTRL), diet supplemented with 7% soybean oil (SOY), SOY + 3.5% virgin coconut oil (COCO), and SOY + 3.5% evening primrose oil (EP) for 4 weeks. The content of insoluble fiber in CTRL was higher than in SOY, COCO, or EP. Body weight gain and food/water intake were measured. At day 28, biometric, biochemical, CV parameters, GI motor function (X-ray and colon bead expulsion test), and visceral sensitivity were evaluated. Changes in propulsive colonic activity were determined in vitro. The colon and adipose tissue were histologically studied; the number of mast cells (MCs) in the colon was calculated.

RESULTS

SOY, COCO, and EP had increased body weight gain but decreased food intake vs CTRL. Water consumption, biometric, biochemical, and CV parameters were comparable between groups. SOY increased the sensitivity to colonic distention. All groups maintained regular propulsive neurogenic contractions; EP delayed colonic motility (P < 0.01). SOY, COCO, and EP displayed decreased size of the cecum, lower number and size of fecal pellets, and higher infiltration of MCs to the colon (P < 0.001).

CONCLUSIONS AND INFERENCES

Dietary FAs supplementation and lower intake of insoluble fiber can induce changes in the motility of the lower GI tract, in vivo and in vitro, but CV function and visceral sensitivity are not generally affected.

Nonpharmacological Modulation of Chronic Inflammation in Parkinson's Disease: Role of Diet Interventions

Neuroinflammation is increasingly recognized as an important pathophysiological feature of neurodegenerative diseases such as Parkinson's disease (PD). Recent evidence suggests that neuroinflammation in PD might originate in the intestine and the bidirectional communication between the central and enteric nervous system, the so-called "gut-brain axis," has received growing attention due to its contribution to the pathogenesis of neurological disorders. Diet targets mediators of inflammation with various mechanisms and combined with dopaminergic treatment can exert various beneficial effects in PD. Food-based therapies may favorably modulate gut microbiota composition and enhance the intestinal epithelial integrity or decrease the proinflammatory response by direct effects on immune cells. Diets rich in pre- and probiotics, polyunsaturated fatty acids, phenols including flavonoids, and vitamins, such as the Mediterranean diet or a plant-based diet, may attenuate chronic inflammation and positively influence PD symptoms and even progression of the disease. Dietary strategies should be encouraged in the context of a healthy lifestyle with physical activity, which also has neuroimmune-modifying properties. Thus, diet adaptation appears to be an effective additive, nonpharmacological therapeutic strategy that can attenuate the chronic inflammation implicated in PD, potentially slow down degeneration, and thereby modify the course of the disease. PD patients should be highly encouraged to adopt corresponding lifestyle modifications, in order to improve not only PD symptoms, but also general quality of life. Future research should focus on planning larger clinical trials with dietary interventions in PD in order to obtain hard evidence for the hypothesized beneficial effects.

A high-sugar diet rapidly enhances susceptibility to colitis via depletion of luminal short-chain fatty acids in mice

Western-style diets have been implicated in triggering inflammatory bowel disease activity. The aim of this study was to identify the effect of a short-term diet high in sugar on susceptibility to colitis. Adult wild-type mice were placed on chow or a high sugar diet (50% sucrose) ± acetate. After two days of diet, mice were treated with dextran sodium sulfate (DSS) to induce colitis. Disease severity was assessed daily. Colonic tissues were analyzed for cytokine expression using the MesoScale discovery platform. Intestinal dextran permeability and serum lipopolysaccharide levels (LPS) were measured. Gut microbiota were analyzed by 16s rRNA sequencing and short chain fatty acid (SCFA) concentrations by gas chromatography. Bone marrow-derived macrophages (BMDM) were incubated with LPS and cytokine secretion measured. Mice on a high sugar diet had increased gut permeability, decreased microbial diversity and reduced SCFA. BMDM derived from high sugar fed mice were highly responsive to LPS. High sugar fed mice had increased susceptibility to colitis and pro-inflammatory cytokine concentrations. Oral acetate significantly attenuated colitis in mice by restoring permeability. In conclusion, short term exposure to a high sugar diet increases susceptibility to colitis by reducing short-chain fatty acids and increasing gut permeability.

Polyphenols and IUGR Pregnancies: Effects of Maternal Hydroxytyrosol Supplementation on Hepatic Fat Accretion and Energy and Fatty Acids Profile of Fetal Tissues

Maternal supplementation with hydroxytyrosol, a polyphenol present in olive leaves and fruits, is a highly promising strategy to improve the oxidative and metabolic status of fetuses at risk of intrauterine growth restriction, which may diminish the appearance of low-birth-weight neonates. The present study aimed to determine whether hydroxytyrosol, by preventing lipid peroxidation, may influence the fat accretion and energy homeostasis in the liver, as well as the fatty acid composition in the liver and muscle. The results indicate that hydroxytyrosol treatment significantly decreased the energy content of the fetal liver, without affecting fat accretion, and caused significant changes in the availability of fatty acids. There were significant increases in the amount of total polyunsaturated fatty acids, omega-3 and omega-6, which are highly important for adequate fetal tissue development. However, there were increases in the omega-6/omega-3 ratio and the desaturation index, which make further studies necessary to determine possible effects on the pro/anti-inflammatory status of the fetuses.

Impact of Genes and the Environment on the Pathogenesis and Disease Course of Inflammatory Bowel Disease

Crohn's disease and ulcerative colitis constitute two major subgroups of inflammatory bowel diseases (IBD), a group of complex polygenic diseases characterized by chronic and progressive inflammation in the gastrointestinal tract. In recent years, methodological advances in genetic analysis have greatly expanded our understanding of the genetic background of IBD. So far, more than 240 genetic risk loci have been identified for IBD. However, these risk alleles explain less than 30% of the susceptibility to disease development, suggesting that environmental factors contribute considerably. The increasing occurrence of IBD in Eastern countries following their 'westernization', as well as the increased risk of disease among those who migrate to high-incidence regions, also suggest that the environment is key in the pathogenesis of IBD. In this review, we summarize the current evidence on the role of genetic and environmental factors in the susceptibility to, and disease course of, IBD, and we suggest how these findings might be applied to clinical practice.

Dietary Support in Elderly Patients with Inflammatory Bowel Disease

Ageing of the human population has become a big challenge for health care systems worldwide. On the other hand, the number of elderly patients with inflammatory bowel disease (IBD) is also increasing. Considering the unique clinical characteristics of this subpopulation, including many comorbidities and polypharmacy, the current therapeutic guidelines for the management of IBD should be individualized and applied with caution. This is why the role of non-pharmacological treatments is of special significance. Since both IBD and older age are independent risk factors of nutritional deficiencies, appropriate dietary support should be an important part of the therapeutic approach. In this review paper we discuss the interrelations between IBD, older age, and malnutrition. We also present the current knowledge on the utility of different diets in the management of IBD. Considering the limited data on how to support IBD therapy by nutritional intervention, we focus on the Mediterranean and Dietary Approaches to Stop Hypertension diets, which seem to be the most beneficial in this patient group. We also discuss some new findings on their hypothetical anti-inflammatory influence on the course of IBD.

Effects of Fish n-3 PUFAs on Intestinal Microbiota and Immune System

Studies over several decades have documented the beneficial actions of n-3 polyunsaturated fatty acids (PUFAs), which are plentiful in fish oil, in different disease states. Mechanisms responsible for the efficacy of n-3 PUFAs include: (1) Reduction of triglyceride levels; (2) anti-arrhythmic and antithrombotic effects, and (3) resolution of inflammatory processes. The human microbiota project and subsequent studies using next-generation sequencing technology have highlighted that thousands of different microbial species are present in the human gut, and that there has been a significant variability of taxa in the microbiota composition among people. Several factors (gestational age, mode of delivery, diet, sanitation and antibiotic treatment) influence the bacterial community in the human gastrointestinal tract, and among these diet habits play a crucial role. The disturbances in the gut microbiota composition, i.e., gut dysbiosis, have been associated with diseases ranging from localized gastrointestinal disorders to neurologic, respiratory, metabolic, ocular, and cardiovascular illnesses. Many studies have been published about the effects of probiotics and prebiotics on the gut microbiota/microbioma. On the contrary, PUFAs in the gut microbiota have been less well defined. However, experimental studies suggested that gut microbiota, n-3 PUFAs, and host immune cells work together to ensure the intestinal wall integrity. This review discussed current evidence concerning the links among gut microbiota, n-3 PUFAs intake, and human inflammatory disease.

Diet and inflammatory bowel disease: The Asian Working Group guidelines

INTRODUCTION

These Asian Working Group guidelines on diet in inflammatory bowel disease (IBD) present a multidisciplinary focus on clinical nutrition in IBD in Asian countries.

METHODOLOGY

The guidelines are based on evidence from existing published literature; however, if objective data were lacking or inconclusive, expert opinion was considered. The conclusions and 38 recommendations have been subject to full peer review and a Delphi process in which uniformly positive responses (agree or strongly agree) were required.

RESULTS

Diet has an important role in IBD pathogenesis, and an increase in the incidence of IBD in Asian countries has paralleled changes in the dietary patterns. The present consensus endeavors to address the following topics in relation to IBD: (i) role of diet in the pathogenesis; (ii) diet as a therapy; (iii) malnutrition and nutritional assessment of the patients; (iv) dietary recommendations; (v) nutritional rehabilitation; and (vi) nutrition in special situations like surgery, pregnancy, and lactation.

CONCLUSIONS

Available objective data to guide nutritional support and primary nutritional therapy in IBD are presented as 38 recommendations.

Urban-rural environmental exposure during childhood and subsequent risk of inflammatory bowel disease: a meta-analysis

BACKGROUND

The relationship between living conditions in urban and rural areas during childhood and subsequent inflammatory bowel disease (IBD) remains controversial.

AIM

To explore the association between environmental exposures early in life and the subsequent risk of IBD.

METHODS

Literature searches were conducted in the following databases: PubMed, EMBASE, and Conference Proceedings Citation Index. Studies were analyzed separately using rate ratios (RRs) or odds ratios (ORs) with 95% confidence intervals.

RESULTS

The search strategy identified 15 studies. Of these, 9 studies explored the association between urban exposure during childhood and ulcerative colitis (UC), and 12 and 4 studies explored this relationship with Crohn's disease (CD) and IBD, respectively. A meta-analysis showed that the pooled ORs estimated for the case-control studies of UC, CD, and IBD were 1.16 (0.83, 1.61), 1.45 (1.45, 1.85), and 1.34 (1.11, 1.62), respectively. The pooled RR estimated for the cohort studies of CD and IBD was 1.48 (1.17, 1.87). The stratified analysis and meta-regression showed significant relationships between CD and living conditions in case-control studies published during 2010-2017 and in non-European countries (P < 0.05).

CONCLUSIONS

Living conditions during childhood are positively associated with the subsequent development of IBD. Urban living environment is more common among those with CD than UC.

Metabolite-Sensing G Protein-Coupled Receptors Connect the Diet-Microbiota-Metabolites Axis to Inflammatory Bowel Disease

Increasing evidence has indicated that diet and metabolites, including bacteria- and host-derived metabolites, orchestrate host pathophysiology by regulating metabolism, immune system and inflammation. Indeed, autoimmune diseases such as inflammatory bowel disease (IBD) are associated with the modulation of host response to diets. One crucial mechanism by which the microbiota affects the host is signaling through G protein-coupled receptors (GPCRs) termed metabolite-sensing GPCRs. In the gut, both immune and nonimmune cells express GPCRs and their activation generally provide anti-inflammatory signals through regulation of both the immune system functions and the epithelial integrity. Members of GPCR family serve as a link between microbiota, immune system and intestinal epithelium by which all these components crucially participate to maintain the gut homeostasis. Conversely, impaired GPCR signaling is associated with IBD and other diseases, including hepatic steatosis, diabetes, cardiovascular disease, and asthma. In this review, we first outline the signaling, function, expression and the physiological role of several groups of metabolite-sensing GPCRs. We then discuss recent findings on their role in the regulation of the inflammation, their existing endogenous and synthetic ligands and innovative approaches to therapeutically target inflammatory bowel disease.

Implications of the Westernized Diet in the Onset and Progression of IBD

Inflammatory bowel diseases (IBD) are currently considered multifactorial pathologies in which various combined environmental factors act on a genetic background, giving rise to a chronic inflammation of the gastrointestinal tract. Among the various environmental factors, it now seems clear that the diet plays the major role in IBD onset and progression. Several clinical studies have attempted to understand the impact of diet in the development and progression of these diseases in order to establish useful guidelines for their management. However, the modest and sometimes contradictory results did not lead to the definition of shared dietary suggestions. On the other hand, food fads and recommendations based on anecdotal episodes are often followed by IBD patients to improve their diet. This review provides a critical overview of existing data on the role of diet as a risk factor for IBD. The methodology used was that of analyzing the results of clinical studies conducted on diet and IBD over the last 12 years through PubMed, as well as analyzing the most relevant studies on nutrients and their possible roles in IBD through the knowledge of the mechanisms by which they can modulate the microbiota or the intestinal physiology.

Contribution of Non-immune Cells to Activation and Modulation of the Intestinal Inflammation

The mucosal immune system constitutes a physical and dynamic barrier against foreign antigens and pathogens and exerts control mechanisms to maintain intestinal tolerance to the microbiota and food antigens. Chronic alterations of the intestinal homeostasis predispose to inflammatory diseases of the gastrointestinal tract, such as Inflammatory Bowel Diseases (IBD). There is growing evidence that the frequency and severity of these diseases are increasing worldwide, which may be probably due to changes in environmental factors. Several stromal and immune cells are involved in this delicate equilibrium that dictates homeostasis. In this review we aimed to summarize the role of epithelial cells and fibroblasts in the induction of mucosal inflammation in the context of IBD. It has been extensively described that environmental factors are key players in this process, and the microbiome of the gastrointestinal tract is currently being intensively investigated due to its profound impact the immune response. Recent findings have demonstrated the interplay between dietary and environmental components, the gut microbiome, and immune cells. "Western" dietary patterns, such as high caloric diets, and pollution can induce alterations in the gut microbiome that in turn affect the intestinal and systemic homeostasis. Here we summarize current knowledge on the influence of dietary components and air particulate matters on gut microbiome composition, and the impact on stromal and immune cells, with a particular focus on promoting local inflammation.

Impact of red meat, processed meat and fibre intake on risk of late-onset chronic inflammatory diseases: prospective cohort study on lifestyle factors using the Danish 'Diet, Cancer and Health' cohort (PROCID-DCH): protocol

INTRODUCTION

Chronic inflammatory diseases (CIDs) (Crohn's disease, ulcerative colitis, psoriasis, psoriatic arthritis, rheumatoid arthritis and multiple sclerosis) are diseases of the immune system that have some shared genetic and environmental predisposing factors, but still few studies have investigated the effects of lifestyle on disease risk of several CIDs. The primary aim of this prospective cohort study is to investigate the impact of fibre, red meat and processed meat on risk of late-onset CID, with the perspective that results of this study can contribute in supporting future diet recommendations for effective personalised prevention.

METHODS AND ANALYSIS

The study will use data from 57 053 persons from the prospective Danish cohort study 'Diet, Cancer and Health' together with National Health Registry data. The follow-up period is from December 1993 to December 2018. Questionnaire data on diet and lifestyle were collected at entry to the Diet, Cancer and Health study. The outcome CID is defined as having a diagnosis of one of the CIDs registered in the National Patient Registry or, for multiple sclerosis, in the Danish Multiple Sclerosis Registry during follow-up and being treated with a drug used for the specific disease. The major outcome of the analyses will be to detect variability in risk of late onset of any CID and, if power allows, disease risk of late onset of each CID diagnosis between persons with different fibre and red meat, and processed meat intake. The outcome will be adjusted for age, sex, body mass index, physical activity, energy, alcohol, fermented dairy products, education, smoking status, hormone replacement therapy and comorbidity.

ETHICS AND DISSEMINATION

The study is approved by the Danish Data Protection Agency (2012-58-0018). The core study is an open register-based cohort study. The study does not need approval from the Ethics committee or Institutional Review Board by Danish law. Study findings will be disseminated through peer-reviewed journals, patient associations and presentations at international conferences.

TRIAL REGISTRATION NUMBER

NCT03456206; Post-results.

Implementing Dietary Modifications and Assessing Nutritional Adequacy of Diets for Inflammatory Bowel Disease

Guidelines for dietary recommendations and nutritional therapy for patients with inflammatory bowel disease (IBD) are lacking, and patients are moving toward popular defined diets for relief of symptoms and inflammation. However, many proposed diets involve elimination of specific foods or food groups and may exacerbate or inadequately replete micronutrient deficiencies that are prevalent in patients with IBD at baseline. Further, limited data are available to guide clinicians on the use of dietary protocols for IBD. This article reviews dietary risk factors for IBD and common beliefs about diet among patients with IBD, and how these aspects may inform general dietary recommendations for this patient population. Additionally, this article reviews dietary interventions used in the management of active IBD, with a focus on whole food diet-based therapies rather than enteral or parenteral nutrition, as well as their nutritional adequacy. This article also highlights various dietary concepts and approaches among patients with IBD, along with the potential for nutritional inadequacy of popular defined diets for IBD. Partnerships with registered dietitians are needed to guide patients with IBD in nutrition and dietary intervention. Larger randomized studies are needed to support evidence-based dietary recommendations for IBD.

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.

Dietary interventions for induction and maintenance of remission in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD), comprised of Crohn's disease (CD) and ulcerative colitis (UC), is characterized by chronic mucosal inflammation, frequent hospitalizations, adverse health economics, and compromised quality of life. Diet has been hypothesised to influence IBD activity.

OBJECTIVES

To evaluate the efficacy and safety of dietary interventions on IBD outcomes.

SEARCH METHODS

We searched the Cochrane IBD Group Specialized Register, CENTRAL, MEDLINE, Embase, Web of Science, Clinicaltrials.gov and the WHO ICTRP from inception to 31 January 2019. We also scanned reference lists of included studies, relevant reviews and guidelines.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared the effects of dietary manipulations to other diets in participants with IBD. Studies that exclusively focused on enteral nutrition, oral nutrient supplementation, medical foods, probiotics, and parenteral nutrition were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, extracted data and assessed bias using the risk of bias tool. We conducted meta-analyses where possible using a random-effects model and calculated the risk ratio (RR) and corresponding 95% confidence interval (CI) for dichotomous outcomes. We assessed the certainty of evidence using GRADE.

MAIN RESULTS

The review included 18 RCTs with 1878 participants. The studies assessed different dietary interventions for active CD (six studies), inactive CD (seven studies), active UC (one study) and inactive UC (four studies). Dietary interventions involved either the consumption of low amounts or complete exclusion of one or more food groups known to trigger IBD symptoms. There was limited scope for data pooling as the interventions and control diets were diverse. The studies were mostly inadequately powered. Fourteen studies were rated as high risk of bias. The other studies were rated as unclear risk of bias.The effect of high fiber, low refined carbohydrates, low microparticle diet, low calcium diet, symptoms-guided diet and highly restricted organic diet on clinical remission in active CD is uncertain. At 4 weeks, remission was induced in: 100% (4/4) of participants in the low refined carbohydrates diet group compared to 0% (0/3) of participants in the control group (RR 7.20, 95% CI 0.53 to 97.83; 7 participants; 1 study; very low certainty evidence). At 16 weeks, 44% (23/52) of participants in the low microparticle diet achieved clinical remission compared to 25% (13/51) of control-group participants (RR 3.13, 95% CI 0.22 to 43.84; 103 participants; 2 studies; I² = 73%; very low certainty evidence). Fifty per cent (16/32) of participants in the symptoms-guided diet group achieved clinical remission compared to 0% (0/19) of control group participants (RR 20.00, 95% CI 1.27 to 315.40; 51 participants ; 1 study; very low certainty evidence) (follow-up unclear). At 24 weeks, 50% (4/8) of participants in the highly restricted organic diet achieved clinical remission compared to 50% (5/10) of participants in the control group (RR 1.00, 95% CI 0.39 to 2.53; 18 participants; 1 study; very low certainty evidence). At 16 weeks, 37% (16/43) participants following a low calcium diet achieved clinical remission compared to 30% (12/40) in the control group (RR 1.24, 95% CI 0.67 to 2.29; 83 participants; 1 study; very low certainty evidence).The effect of low refined carbohydrate diets, symptoms-guided diets and low red processed meat diets on relapse in inactive CD is uncertain. At 12 to 24 months, 67% (176/264) of participants in low refined carbohydrate diet relapsed compared to 64% (193/303) in the control group (RR 1.04, 95% CI 0.87 to 1.25; 567 participants; 3 studies; I² = 35%; low certainty evidence). At 6 to 24 months, 48% (24/50) of participants in the symptoms-guided diet group relapsed compared to 83% (40/48) participants in the control diet (RR 0.53, 95% CI 0.28 to 1.01; 98 participants ; 2 studies; I² = 54%; low certainty evidence). At 48 weeks, 66% (63/96) of participants in the low red and processed meat diet group relapsed compared to 63% (75/118) of the control group (RR 1.03, 95% CI 0.85 to 1.26; 214 participants; 1 study; low certainty evidence). At 12 months, 0% (0/16) of participants on an exclusion diet comprised of low disaccharides / grains / saturated fats / red and processed meat experienced clinical relapse compared to 26% (10/38) of participants on a control group (RR 0.11, 95% CI 0.01 to 1.76; 54 participants; 1 study; very low certainty evidence).The effect of a symptoms-guided diet on clinical remission in active UC is uncertain. At six weeks, 36% (4/11) of symptoms-guided diet participants achieved remission compared to 0% (0/10) of usual diet participants (RR 8.25, 95% CI 0.50 to 136.33; 21 participants; 1 study; very low certainty evidence).The effect of the Alberta-based anti-inflammatory diet, the Carrageenan-free diet or milk-free diet on relapse rates in inactive UC is uncertain. At 6 months, 36% (5/14) of participants in the Alberta-based anti-inflammatory diet group relapsed compared to 29% (4/14) of participants in the control group (RR 1.25, 95% CI 0.42 to 3.70; 28 participants; 1 study; very low certainty evidence). Thirty per cent (3/10) of participants following the carrageenan-free diet for 12 months relapsed compared to 60% (3/5) of the participants in the control group (RR 0.50, 95% CI 0.15 to 1.64; 15 participants; 1 study; very low certainty evidence). At 12 months, 59% (23/39) of milk free diet participants relapsed compared to 68% (26/38) of control diet participants (RR 0.83, 95% CI 0.60 to 1.15; 77 participants; 2 studies; I² = 0%; low certainty evidence).None of the included studies reported on diet-related adverse events.

AUTHORS' CONCLUSIONS

The effects of dietary interventions on CD and UC are uncertain. Thus no firm conclusions regarding the benefits and harms of dietary interventions in CD and UC can be drawn. There is need for consensus on the composition of dietary interventions in IBD and more RCTs are required to evaluate these interventions. Currently, there are at least five ongoing studies (estimated enrollment of 498 participants). This review will be updated when the results of these studies are available.

Dietary intake of fish, n-3 polyunsaturated fatty acids, and risk of inflammatory bowel disease: a systematic review and meta-analysis of observational studies

PURPOSE

Fish consumption and dietary intake of n-3 polyunsaturated acids (PUFAs) may be associated with inflammatory bowel disease (IBD). We aimed to conduct a systematic review and summarize published articles on the association between fish consumption and dietary intake of n-3 PUFAs with the risk of IBD.

METHODS

PubMed, Scopus, and Web of Science databases were used to conduct a comprehensive search and identify eligible literature published prior to January 2019. Fixed-effects model or random-effects models (DerSimonian-Laird method) were applied to pool the effect sizes. Cochrane Q test was used to trace the potential source of heterogeneity across studies.

RESULTS

12 studies (5 prospective and 7 case-control) were included in the systematic review, which ten of them were eligible for inclusion in the meta-analysis. Studies were included a total sample size of 282610 participants which 2002 of them were cases of IBD [1061 Crohn's disease (CD) and 937 ulcerative colitis (UC)]. A negative association was found between fish consumption and the incidence of CD (pooled effect size: 0.54, 95%CI: 0.31-0.96, P = 0.03). There was no relationship between total dietary n-3 PUFAs intake and IBD (pooled effect size: 1.17, 95%CI: 0.80-1.72, P = 0.41). A significant inverse association was observed between dietary long-chain n-3 PUFAs and the risk of UC (pooled effect size: 0.75, 95%CI: 0.57-0.98, P = 0.03). Moreover, no association was found between α-Linolenic acid (ALA) and IBD (pooled effect size: 1.17, 95%CI: 0.63-2.17, P = 0.62).

CONCLUSIONS

Findings showed a negative association between fish consumption and the risk of CD. Moreover, there was a significant inverse association between dietary long-chain n-3 PUFAs and the risk of UC.

Mechanisms of Disease: Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs), represented by Crohn disease and ulcerative colitis, are associated with major morbidity in Western countries and with increasing incidence in the developing world. Although analysis of the genome of patients with IBD, especially through genome-wide association studies, has unraveled multiple pathways involved in IBD pathogenesis, only part of IBD heritability has been explained by genetic studies. This finding has revealed that environmental factors also play a major role in promoting intestinal inflammation, mostly through their effects in the composition of the microbiome. However, in order for microbial dysbiosis to result in uncontrolled intestinal inflammation, the intestinal barrier formed by intestinal epithelial cells and the innate immune system should also be compromised. Finally, activation of the immune system depends on the working balance between effector and regulatory cells present in the intestinal mucosa, which have also been found to be dysregulated in this patient population. Therefore, IBD pathogenesis is a result of the interplay of genetic susceptibility and environmental impact on the microbiome that through a weakened intestinal barrier will lead to inappropriate intestinal immune activation. In this article, we will review the mechanisms proposed to cause IBD from the genetic, environmental, intestinal barrier, and immunologic perspectives.

The role of dietary factors in inflammatory bowel diseases: New perspectives

The current review aimed to elucidate the role of diet in every stage of inflammatory bowel diseases, from aspects of prevention, treatment and rehabilitation. Western diet, characterized by overconsumption of refined sugar and saturated fat and low consumption of dietary fiber, may partly be blamed for its pathogenesis. Some immune-modulated nutrients (fibers, monounsaturated fatty acids, n-3 polyunsaturated fatty acids and vitamin D) exert their potential beneficial effects on gut microbiota and immune function, resulting in clinical remission and/or preventing relapse. However, data is limited to conclude optimal micronutrient levels and therapeutic implications. Further, diet itself is complex; therefore, it is reasonable to evaluate diet as a whole rather than a single type of food. Some specific dietary patterns are generated for the management of inflammatory bowel diseases with controversial results. Only exclusive enteral nutrition has been widely recommended for pediatric patients with non-stricturing active Crohn's disease. Self-monitoring, avoidance of certain types of foods, limited intake of alcohol and smoking, supplementation of minerals and vitamins if deficiency is confirmed, and adherence to the diet enriched in vegetables and fruits and low in animal food and un-digested fiber during flares are the most common dietary recommendation. Further clinical trials with a high evidence rank are warranted.