Effects of enteral nutrition on Crohn's disease: clues to the impact of diet on disease pathogenesis

Inflammatory Diseases of the Gut

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic inflammatory disorders of the gastrointestinal tract whose prevalence has been dramatically increasing over the past decade. New studies have shown that IBD is the second most common chronic inflammatory disease worldwide after rheumatoid arthritis, affecting millions of people mainly in industrialized countries. Symptoms of IBD include frequent bloody diarrhea, abdominal cramping, anorexia, abdominal distension, and emesis. Although the exact etiology is unknown, it has been postulated that immunological, microbial, environmental, nutritional, and genetic factors contribute to the pathogenesis and severity of IBD. Today, no treatment has consistently been shown to be successful in treating IBD. This review summarizes current research on the epidemiology, etiology, pathophysiology, and existing treatment approaches, including pharmaceutical and nutritional options for IBD.

Enteral Nutrition in the Management of Crohn's Disease: Reviewing Mechanisms of Actions and Highlighting Potential Venues for Enhancing the Efficacy

Crohn's disease (CD) is a chronic condition that affects the gut and has adverse effects on growth and development. There is a global increase in the incidence and prevalence rates, and several factors are believed to contribute to this rise, including dietary habits. In contrast, the use of enteral nutrition (EN) as an exclusive source of nutrition is increasingly becoming the preferred induction treatment of pediatric CD patients in part to address the nutrition complications. However, EN therapy is considered less effective in adults with CD. A better understanding of the molecular mechanisms of enteral therapy will help improve the clinical management of CD. It is increasingly becoming evident that the therapeutic utility of EN is in part due to the reversal of the microbial changes and the direct immunomodulatory effects. Moreover, there is a potential tendency for enhancing the efficacy of EN therapy by improving the palatability of the given formulas and, more important, by magnifying the anti-inflammatory properties. Recent observations have shown that the immunomodulatory effects of EN are mediated at least in part by blocking nuclear factor-κB. Furthermore, it is likely that several ingredients of EN contribute to this activity, in particular glutamine and arginine amino acids. In addition, manipulating the composition of EN therapy by altering concentrations of the key ingredients is found to have the potential for more efficient therapy. In this review, the underlying mechanisms of EN actions will be discussed further with a focus on the potential methods for enhancing the efficacy.

Regulation of Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-κβ) in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD), encompassing both Crohn Disease (CD) and ulcerative colitis (UC) are globally prevalent diseases, impacting children of all ages. The hallmark of IBD is a perturbed immune system that leads to continuous inflammation in the gut and challenges optimal treatment. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κβ), a nuclear transcription factor, plays a major role in gut homeostasis and contributes significantly toward a balanced, homeostatic immune system. Dysregulation in the NF-κβ pathway and factors that regulate it lead to a state of uncontrolled inflammation and altered immunity, as typically observed in IBD. Levels of proinflammatory cytokines that are regulated through NF-κβ are increased in both CD and UC. Genes known to activate NF-κβ, such as, Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) and Interleukin 23 (IL-23), are associated with IBD. Factors involved in inhibition of NF-κβ, such as A20 and TOLLIP, are also affected in IBD, resulting in failed inflammation suppression/regulation. NOD-2 and A20 have specifically been found to be strongly associated with pediatric IBD. Gut commensals are known to exert anti-inflammatory activities toward NF-κβ and can have a potential role in attenuating inflammation that likely occurs due to microbial dysbiosis in IBD. Failure to terminate/downregulate NF-κβ signaling results in chronic inflammation in IBD. Well-regulated control of inflammation in children with IBD can help better control the disease and suppress immune responses. Better understanding of factors that control NF-κβ can potentially lead toward discovering targeted therapeutic interventions for IBD. Suppression of NF-κβ can be achieved through many modalities including anti-sense oligonucleotides (ASOs), siRNA (small interfering RNA), factors regulating NF-κβ, and microbes. This review focuses on the role of NF-κβ, especially in pediatric IBD, and potential therapeutic venues for attenuating NF-κβ-induced inflammation.

Research Gaps in Diet and Nutrition in Inflammatory Bowel Disease. A Topical Review by D-ECCO Working Group [Dietitians of ECCO]

Although the current doctrine of IBD pathogenesis proposes an interaction between environmental factors and gut microbiota in genetically susceptible individuals, dietary exposures have attracted recent interest and are, at least in part, likely to explain the rapid rise in disease incidence and prevalence. The D-ECCO working group along with other ECCO experts with expertise in nutrition, microbiology, physiology, and medicine reviewed the evidence investigating the role of diet and nutritional therapy in the onset, perpetuation, and management of IBD. A narrative topical review is presented where evidence pertinent to the topic is summarised collectively under three main thematic domains: i] the role of diet as an environmental factor in IBD aetiology; ii] the role of diet as induction and maintenance therapy in IBD; and iii] assessment of nutritional status and supportive nutritional therapy in IBD. A summary of research gaps for each of these thematic domains is proposed, which is anticipated to be agenda-setting for future research in the area of diet and nutrition in IBD.

Dietary Therapy With the Crohn's Disease Exclusion Diet is a Successful Strategy for Induction of Remission in Children and Adults Failing Biological Therapy

BACKGROUND

Loss of response [LoR] to biologics in Crohn's disease [CD] is a significant clinical problem. Dietary therapy as a treatment strategy in this setting has not been previously reported. We report the use of dietary strategies using enteral nutrition coupled with the Crohn's Disease Exclusion Diet [CDED] for LoR to infliximab or adalimumab as a single-centre experience.

METHODS

Patients with LoR to a biologic despite dose escalation or combination therapy were treated with partial enteral nutrition [PEN] by a polymeric formula and the CDED for 12 weeks. Paediatric patients with severe flares received 14 days of exclusive enteral nutrition followed by PEN + CDED as above. All patients were seen at weeks 6 and 12 for follow up. Current and prior treatment, Harvey Bradshaw Index [HBI], C-reactive protein [CRP] and albumin were recorded. Remission was defined as HBI <5 at week 6.

RESULTS

Twenty-one patients, mean age 22.1 ± 8.9 years [11 adults and ten children] met study criteria. Seventeen patients [81%] had used combination therapy, and 10/21 [47.6%] had failed a second biologic. Seven patients had a prior intestinal resection. Dose escalation had failed in 13/21 [62%] patients. Clinical remission by physician's global assessment and HBI after 6 weeks was obtained in 13/21 [61.9%]. Mean HBI decreased from 9.4 ± 4.2 to 2.6 ± 3.8 [p < 0.001], mean CRP decreased from 2.8 ± 3.4 to 0.7 ± 0.5 [p = 0.005] and mean albumin increased from 3.5 ± 0.6 to 3.8 ± 0.5 [p = 0.06].

CONCLUSION

Dietary treatment combining PEN with the CDED may be a useful salvage regimen for patients failing biological therapy despite dose escalation.

Exclusive Enteral Nutrition Therapy in Paediatric Crohn's Disease Results in Long-term Avoidance of Corticosteroids: Results of a Propensity-score Matched Cohort Analysis

BACKGROUND AND AIMS

Exclusive enteral nutrition [EEN] is recommended as a first-line induction therapy for paediatric Crohn's disease [CD] although corticosteroids [CS] are still used commonly. Our aim was to compare short- and long-term disease outcomes of paediatric CD patients initially managed with either EEN or CS.

METHODS

Medical records of newly diagnosed paediatric CD patients treated with EEN or CS as induction therapy were retrospectively reviewed. To minimise selection bias inherent in observational cohort studies, propensity analysis was carried out. Data on anthropometrics, medical history, and presenting phenotype were collected at time of diagnosis [baseline]; outcomes of interest, including medication use, hospitalisation, surgical procedures, and disease progression were assessed up to 6 years following diagnosis.

RESULTS

Of 127 patients reviewed, a total of 111 propensity-score matched CD patients receiving EEN [n = 76] or CS [n = 35] were analysed. By 4-12 weeks of induction therapy, 86.6% of EEN-treated patients achieved remission (Paediatric Crohn's Disease Activity Index [PCDAI] ≤ 7.5) compared with 58.1% of patients in the CS-treated group [p < 0.01]. Choice of EEN over CS for induction was associated with avoidance of corticosteroids over a 6-year follow-up period. Analysis of long-term linear growth, hospitalisation, need for biologic therapy, or surgical intervention did not reveal any significant differences.

CONCLUSIONS

These findings suggest that EEN induction therapy is more effective in achieving early remission and is associated with long-term steroid avoidance without increased use of biologics or need for surgery.

Efficacy of exclusive enteral nutrition in complicated Crohn's disease

AIM

To investigate the efficacy of exclusive enteral nutrition (EEN) in induction of remission in adult active Crohn's disease (CD) complicated with intestinal fistula/abdominal abscess or inflammatory intestinal stricture.

METHOD

Patients diagnosed with active CD with complications were recruited between July 2013 and July 2015. Patients were offered EEN for 12 weeks. Patients with abscess received antibiotic treatment with or without percutaneous drainage. Clinical variables were recorded (ClinicalTrials.gov Identifier: NCT02887287).

RESULTS

Forty-one patients with CD and with intestinal fistula/abdominal abscess or inflammatory intestinal stricture aged 18-60 years, were included. Ten patients were accompanied with stenosis and 33 with intestinal fistula/abscess. After 12 weeks of EEN, the Crohn's disease activity index significantly decreased (223.43 ± 65.5 vs. 106.77 ± 42.73, p ≤ .001), and 80.5% of patients achieved full clinical remission totally. Fistula closure after EEN was observed in 75% of patients with entero-cutaneous fistula. In patients with stenosis, 20% had no response to EEN and were transferred for surgery. Partial remission and full remission were observed in 20% and 60% of patients after 12 weeks of EEN, respectively. Intra-abdominal abscess resolved in 76% of patients. Seventeen patients who had mucosal ulcers underwent colonoscopy before and after EEN, 47% achieved mucosal healing after the treatment. The inflammatory index of patients significantly decreased (p ≤ .01), nutritional parameters increased (p ≤ .01) and the European Nutritional Risk Screening (2002) decreased (p ≤ .01).

CONCLUSION

EEN is effective in inducing early clinical remission, mucosal healing, promoting fistula closure and reducing the size of abscess in adult CD patients with complications.

Influence of Diet on the Course of Inflammatory Bowel Disease

BACKGROUND

While the importance of diet in the pathogenesis of inflammatory bowel disease (IBD) is generally recognized, influence of food on the course of IBD is little understood.

AIM

The purpose of this study was to assess the association between food intake and course of disease in patients with IBD.

METHODS

We performed a cross-sectional study on 103 adult patients (50 with active disease and 53 in remission, divided by their calprotectin level), who completed a food frequency questionnaire on their intake of several foods over 1 year. Diet, as assessed using a 146-item self-administered food frequency questionnaire, was correlated with objective evidence of disease based on fecal calprotectin levels.

RESULTS

Legumes and potato were inversely associated with disease relapse (p value for trend 0.023) with patients in the highest quartile for legume and potato consumption carrying a 79% lower risk of active disease (adjusted OR 0.21, 95% CI 0.57-0.81). A positive association emerged between meat intake and disease relapse, the highest quartile for meat consumption coinciding with a higher risk of active disease (OR 3.61, 95% CI 1.15-11.38), though this was not significant in the adjusted analysis. No statistically significant associations were found between disease relapse and the intake of vegetables, cereals, dairy products, or fish.

CONCLUSIONS

Our results suggest a potentially protective role of legumes and potato and a detrimental influence of meat in maintaining clinical remission in IBD patients. These findings have important public health implications, but further interventional studies will be needed to demonstrate these associations.

The Impact of Exclusive Enteral Nutrition (EEN) on the Gut Microbiome in Crohn's Disease: A Review

Crohn’s disease (CD), a form of inflammatory bowel disease (IBD), is thought to arise from a complex interaction of genetics, the gut microbiome, and environmental factors, such as diet. There is clear evidence that dietary intervention is successful in the treatment of CD—exclusive enteral nutrition (EEN) is able to induce remission in up to 80% of CD patients. While the mechanism of action of EEN is not clear, EEN is known to cause profound changes in the gut microbiome. Understanding how EEN modifies the gut microbiome to induce remission could provide insight into CD etiopathogenesis and aid the development of microbiome-targeted interventions to guide ongoing dietary therapy to sustain remission. This review includes current literature on changes in composition and function of the gut microbiome associated with EEN treatment in CD patients.

The Role of Carrageenan and Carboxymethylcellulose in the Development of Intestinal Inflammation

Although the exact pathophysiology remains unknown, the development of inflammatory bowel disease (IBD) is influenced by the interplay between genetics, the immune system, and environmental factors such as diet. The commonly used food additives, carrageenan and carboxymethylcellulose (CMC), are used to develop intestinal inflammation in animal models. These food additives are excluded from current dietary approaches to induce disease remission in Crohn's disease such as exclusive enteral nutrition (EEN) using a polymeric formula. By reviewing the existing scientific literature, this review aims to discuss the role that carrageenan and CMC may play in the development of IBD. Animal studies consistently report that carrageenan and CMC induce histopathological features that are typical of IBD while altering the microbiome, disrupting the intestinal epithelial barrier, inhibiting proteins that provide protection against microorganisms, and stimulating the elaboration of pro-inflammatory cytokines. Similar trials directly assessing the influence of carrageenan and CMC in humans are of course unethical to conduct, but recent studies of human epithelial cells and the human microbiome support the findings from animal studies. Carrageenan and CMC may trigger or magnify an inflammatory response in the human intestine but are unlikely to be identified as the sole environmental factor involved in the development of IBD or in disease recurrence after treatment. However, the widespread use of carrageenan and CMC in foods consumed by the pediatric population in a "Western" diet is on the rise alongside a corresponding increase in IBD incidence, and questions are being raised about the safety of frequent usage of these food additives. Therefore, further research is warranted to elucidate the role of carrageenan and CMC in intestinal inflammation, which may help identify novel nutritional strategies that hinder the development of the disease or prevent disease relapse post-EEN treatment.

Increased Epithelial Gap Density in the Noninflamed Duodenum of Children With Inflammatory Bowel Diseases

OBJECTIVES

Inflammatory bowel diseases (IBD) present commonly in childhood, with unknown etiology, but an important role for the epithelial lining is suggested. Epithelial cell extrusion, measured by counting gaps between epithelial cells, is higher in adult patients with Crohn disease (CD) than in controls. Our objectives were to compare epithelial gaps in the duodenum of IBD and non-IBD pediatric patients, to study the correlation between epithelial gaps, inflammation, and disease activity, and identify potential mechanisms.

METHODS

Epithelial gap density of the duodenum was evaluated using probe-based confocal laser endomicroscopy in 26 pediatric patients with IBD (16 CD, 10 ulcerative colitis [UC]) and 17 non-IBD controls during endoscopy. Epithelial gaps were correlated with serum inflammatory markers, disease activity indices, and intraepithelial lymphocytes. A panel of 10 inflammatory cytokines and expression of TNFAIP3 (A20; inhibits NF-κβ-induced inflammation) were analyzed in duodenal and ileal biopsies.

RESULTS

Confocal imaging showed significantly higher epithelial gap density in patients with IBD, including UC. Interleukin (IL)-2 and IL-8 were higher in duodenal but not ileal biopsies of patients with UC. No significant correlation was present between C-reactive protein, erythrocyte sedimentation rate, disease activity indices, and epithelial gaps in patients with UC. In patients with CD, C-reactive protein positively correlated with epithelial gaps. A20 expression in the duodenum was unchanged among non-IBD and IBD cases.

CONCLUSIONS

Duodenal epithelial gaps are increased in pediatric patients with IBD (including UC) but are unrelated to inflammation. This suggests that altered epithelial barrier is an important systemic feature of pediatric IBD and is not only secondary to inflammation.

Microbiota in Inflammatory Bowel Disease Pathogenesis and Therapy: Is It All About Diet?

Inflammatory bowel disease (IBD), including ulcerative colitis, Crohn's disease, and unclassified IBD, continues to cause significant morbidity. While its incidence is increasing, no clear etiology and no cure have yet been discovered. Recent findings suggest that IBD may have a multifactorial etiology, where complex interactions between genetics, epigenetics, environmental factors (including diet but also infections, antibiotics, and sanitation), and host immune system lead to abnormal immune responses and chronic inflammation. Over the past years, the role of altered gut microbiota (in both composition and function) in IBD pathogenesis has emerged as an outstanding area of interest. According to new findings, gut dysbiosis may appear as a key element in initiation of inflammation in IBD and its complications. Moreover, complex metagenomic studies provide possibilities to distinguish between IBD types and appreciate severity and prognosis of the disease, as well as response to therapy. This review provides an updated knowledge of recent findings linking altered bacterial composition and functions, viruses, and fungi to IBD pathogenesis. It also highlights the complex genetic, epigenetic, immune, and microbial interactions in relation to environmental factors (including diet). We overview the actual options to manipulate the altered microbiota, such as modified diet, probiotics, prebiotics, synbiotics, antibiotics, and fecal transplantation. Future possible therapies are also included. Targeting altered microbiota could be the next therapeutic personalized approach, but more research and well-designed comparative prospective studies are required to formulate adequate directions for prevention and therapy.

Toward enteral nutrition for the treatment of pediatric Crohn disease in Canada: a workshop to identify barriers and enablers

The treatment armamentarium in pediatric Crohn disease (CD) is very similar to adult-onset CD with the notable exception of the use of exclusive enteral nutrition (EEN [the administration of a liquid formula diet while excluding normal diet]), which is used more frequently by pediatric gastroenterologists to induce remission. In pediatric CD, EEN is now recommended by the pediatric committee of the European Crohn's and Colitis Organisation and the European Society for Paediatric Gastroenterology Hepatology and Nutrition as a first-choice agent to induce remission, with remission rates in pediatric studies consistently >75%. To chart and address enablers and barriers of use of EEN in Canada, a workshop was held in September 2014 in Toronto (Ontario), inviting pediatric gastroenterologists, nurses and dietitians from most Canadian pediatric IBD centres as well as international faculty from the United States and Europe with particular research and clinical expertise in the dietary management of pediatric CD. Workshop participants ranked the exclusivity of enteral nutrition; the health care resources; and cost implications as the top three barriers to its use. Conversely, key enablers mentioned included: standardization and sharing of protocols for use of enteral nutrition; ensuring sufficient dietetic resources; and reducing the cost of EEN to the family (including advocacy for reimbursement by provincial ministries of health and private insurance companies). Herein, the authors report on the discussions during this workshop and list strategies to enhance the use of EEN as a treatment option in the treatment of pediatric CD in Canada.

Nutritional therapy in inflammatory bowel disease

PURPOSE OF REVIEW

An increasing body of evidence has linked diet to inflammatory bowel diseases (IBD), both Crohn's disease and ulcerative colitis. Most of our current knowledge pertains to the link between diet and Crohn's disease. Exclusive enteral nutrition and partial enteral nutrition are the best known dietary intervention for the induction of remission and maintenance of remission in Crohn's disease both in children and in adults, but the mechanism whereby these interventions may cause or maintain remission and mucosal healing has remained elusive.

RECENT FINDINGS

Recent studies have shed light on the possible mechanisms of response to dietary intervention. Epidemiological and rodent model studies over the last year have supplied us with several dietary candidates for an effect of diet on inflammation and disease pathogenesis. Others have shed insight into the effect of diet on dysbiosis and the microbiota. An elimination diet based on some of these candidates has shown clinical efficacy, and bridged the knowledge obtained from rodent models to a human intervention.

SUMMARY

These studies may allow better understanding of the pathogenesis of IBD and provide new tools to treat these difficult diseases. Elimination diets based on the identification of deleterious dietary components may pave the way for an improved control of the disease in the future.

VIDEO ABSTRACT

http://links.lww.com/COG/A10.

The role of enteral nutrition in patients with inflammatory bowel disease: current aspects

Enteral nutrition (EN) is considered to be of great importance in patients with inflammatory bowel disease (IBD) and nutritional problems. This comprehensive review is aiming to provide the reader with an update on the role of EN in IBD patients. EN can reduce Crohn's disease (CD) activity and maintain remission in both adults and children. Nutritional support using liquid formulas should be considered for CD patients and in serious cases of ulcerative colitis (UC), especially for those who may require prolonged cycles of corticosteroids. Given that the ultimate goal in the treatment of CD is mucosal healing, this advantage of EN over corticosteroid treatment is valuable in therapeutic decision-making. EN is indicated in active CD, in cases of steroid intolerance, in patient's refusal of steroids, in combination with steroids in undernourished individuals, and in patients with an inflammatory stenosis of the small intestine. No differences between the efficiency of elemental diets and nonelemental formulas have been noticed. EN must be the first choice compared to TPN. EN has a restricted value in the treatment of patients with large bowel CD. In conclusion, it seems important not to underestimate the role of nutrition as supportive care in patients with IBD.

Treatment of IBD: where we are and where we are going

In assessing the best evidence for optimizing management of inflammatory bowel disease (IBD), the focus is typically on anti-inflammatory agents and therapies that modulate the immune system. The intestinal immune response remains the key focus of developing therapies as well. In the past decade, the concept of dysbiosis of the gut microbiome has emerged as a potential pathogenetic focus in IBD, and with this a burgeoning interest in manipulating the microbiome as a means of controlling the disease has emerged. In this review, anti-inflammatory, immune-modulating, and microbiome-modulating therapies will be covered in terms of what is known today, as well as treatments that may be part of the therapeutic armamentarium in the near future. Concurrent with the evolution of our understanding of the basic biology of IBD, there is an increasing appreciation for the disconnect between patients' symptoms and inflammatory disease. As clinical trials have simultaneously addressed both symptom scores and mucosal healing, investigators and clinicians have gained a greater appreciation for the fact that many symptoms may not be driven by active inflammation, and hence focusing only on immunomodulatory therapies would not serve patients' needs fully. Furthermore, there is an emerging recognition of the importance of stress and psychological health in symptom experience and treatment needs. In this review, approaches to managing patients' symptoms as well as other adjunctive approaches to improving well-being will also be discussed. Finally, throughout this review, important research questions regarding different aspects of treatment will be proposed.

Review article: the diagnosis and management of food allergy and food intolerances

BACKGROUND

Adverse reactions to food include immune mediated food allergies and non-immune mediated food intolerances. Food allergies and intolerances are often confused by health professionals, patients and the public.

AIM

To critically review the data relating to diagnosis and management of food allergy and food intolerance in adults and children.

METHODS

MEDLINE, EMBASE and the Cochrane Database were searched up until May 2014, using search terms related to food allergy and intolerance.

RESULTS

An estimated one-fifth of the population believe that they have adverse reactions to food. Estimates of true IgE-mediated food allergy vary, but in some countries it may be as prevalent as 4-7% of preschool children. The most common food allergens are cow's milk, egg, peanut, tree nuts, soy, shellfish and finned fish. Reactions vary from urticaria to anaphylaxis and death. Tolerance for many foods including milk and egg develops with age, but is far less likely with peanut allergy. Estimates of IgE-mediated food allergy in adults are closer to 1-2%. Non-IgE-mediated food allergies such as Food Protein-Induced Enterocolitis Syndrome are rarer and predominantly recognised in childhood. Eosinophilic gastrointestinal disorders including eosinophilic oesophagitis are mixed IgE- and non-IgE-mediated food allergic conditions, and are improved by dietary exclusions. By contrast food intolerances are nonspecific, and the resultant symptoms resemble other common medically unexplained complaints, often overlapping with symptoms found in functional disorders such as irritable bowel syndrome. Improved dietary treatments for the irritable bowel syndrome have recently been described.

CONCLUSIONS

Food allergies are more common in children, can be life-threatening and are distinct from food intolerances. Food intolerances may pose little risk but since functional disorders are so prevalent, greater efforts to understand adverse effects of foods in functional disorders are warranted.

Partial enteral nutrition with a Crohn's disease exclusion diet is effective for induction of remission in children and young adults with Crohn's disease

BACKGROUND

Exclusive enteral nutrition is effective for inducing remission in active pediatric Crohn's disease. Partial enteral nutrition (PEN) with free diet is ineffective for inducing remission, suggesting that the mechanism depends on exclusion of free diet. We developed an alternative diet based on PEN with exclusion of dietary components hypothesized to affect the microbiome or intestinal permeability.

METHODS

Children and young adults with active disease defined as a pediatric Crohn's disease activity index >7.5 or Harvey-Bradshaw index ≥4 received a 6-week structured Crohn's disease exclusion diet that allowed access to specific foods and restricted exposure to all other foods, and up to 50% of dietary calories from a polymeric formula. Remission, C-reactive protien, and erythrocyte sedimentation rate were reevaluated at 6 weeks. The primary endpoint was remission at 6 weeks defined as Harvey-Bradshaw index ≤3 for all patients and pediatric Crohn's disease activity index <7.5 in children.

RESULTS

We treated 47 patients (mean age, 16.1 ± 5.6 yr; 34 children). Response and remission were obtained in 37 (78.7%) and 33 (70.2%) patients, respectively. Mean pediatric Crohn's disease activity index decreased from 27.7 ± 9.4 to 5.4 ± 8 (P < 0.001), Harvey-Bradshaw index from 6.4 ± 2.7 to 1.8 ± 2.9 (P < 0.001). Remission was obtained in 70% of children and 69% of adults. Normalization of previously elevated CRP occurred in 21 of 30 (70%) patients in remission. Seven patients used the diet without PEN; 6 of 7 obtained remission.

CONCLUSIONS

Dietary therapy involving PEN with an exclusion diet seems to lead to high remission rates in early mild-to-moderate luminal Crohn's disease in children and young adults.

Dietary clues to the pathogenesis of Crohn's disease

Crohn's disease is a complex inherited disorder of unknown pathogenesis with environmental, genetic and microbial factors involved in the development of the disease. A remarkable feature of this disease in childhood is the effective response to exclusive enteral nutrition (EEN) therapy and the need for complete exclusion of normal diet required for success (principle of exclusivity). EEN or dietary interventions might act through removal of dietary components, which affect microbial composition, decrease a proinflammatory response and promote restitution of the epithelial barrier, likewise allowing termination of this vicious disease-forming cycle before a critical threshold is reached. Multiple traditional and nontraditional dietary components may affect the microbiome, mucous layer, intestinal permeability, or adherence and translocation of pathobionts. We review the epidemiological data, as well as data from animal models and cell lines, and propose a model for pathogenesis we have termed the 'bacterial penetration cycle', whereby dietary components such as animal fat, high sugar intake and gliadin, and consumption of emulsifiers, maltodextrin as well as low-fiber diets may be able to cause a localized acquired bacterial clearance defect, leading to bacterial adhesion and penetration, and subsequently inflammation in the gut.

Should we be treating the bugs instead of cytokines and T cells?

BACKGROUND/AIM

It is now clear that intestinal microbes are involved in many aspects of inflammatory bowel diseases (IBD) and that understanding how microbes lead to disease could present novel opportunities for diagnosis and treatment. Microbes are linked to most disease-associated genetic polymorphisms and are critical mediators of environmental effects (through food, hygiene, and infection). This paper reviews recent findings and future implications for targeting microbes in IBD.

METHODS

A comprehensive review of the literature is presented, with specific focus on how treating microbes could alter patient care in the future.

RESULTS

Human and animal-based research supports the central role of microbes in IBD pathogenesis at multiple levels. Antibiotics, probiotics, diet, and potentially fecal transplantation are all potential treatments for IBD. Animal models of IBD only develop in the presence of microbes and co-housing mice genetically susceptible to gut inflammation with normal mice can lead to the development of bowel injury. Key papers have used microbial sequencing and metagenomics to study the role of microbes in IBD and we are now on the cusp of expanding into clinically relevant fields, such as diagnosis and therapeutics. However, many challenges still remain in understanding how microbes can be manipulated to prevent or treat disease.

CONCLUSIONS

In the future, we may be able to predict risk of disease, define biological subtypes, establish tools for prevention, and even cure IBD using microbes or their products. A broad spectrum of therapeutic tools, spanning from fecal transplantation, probiotics, prebiotics, microbial products to microbe-tailored diets, may replace current IBD treatments.

Popular exclusionary diets for inflammatory bowel disease: the search for a dietary culprit

The evolving understanding of the role of the microbiome and environmental factors in the pathogenesis of inflammatory bowel disease makes diet an interesting and potentially powerful tool in the treatment of disease. However, at this time, evidence is limited but anecdotal reports of success abound. There is a bewildering array of new diets being tried by patients in an attempt to control diseases. This review attempts to summarize the most common diets for the treating physician.