Nutrition support in inflammatory bowel disease

Diet Recommendations for Hospitalized Patients With Inflammatory Bowel Disease: Better Options Than Nil Per Os

Hospitalizations are a time when providers often have uncertainty about what to feed patients with inflammatory bowel disease (IBD). While there are many trials evaluating the role of diet in the management of IBD, the role of diet for the hospitalized patient is less clear. The hospitalization may serve as an opportunity to educate patients about the role of diet, try different diets, and develop dietary recommendations for after discharge. Here, we review the literature for dietary considerations during hospitalizations and acute settings, as well as upon discharge. Patients with IBD benefit from screening and nutritional support for malnutrition and nutritional deficiencies. Enteral nutrition and exclusion diets are promising as induction and maintenance therapies, but no specific recommendations during hospitalization for adult patients are available currently. There are very few reasons to enforce bowel rest or clear liquids other than bowel obstruction, uncontrolled sepsis, or need for urgent or emergent surgery; most patients - including many with penetrating or stricturing disease - benefit from feeding in whichever capacity is tolerated, with enteral and parenteral nutrition used as needed to reach nutritional goals. Future studies are needed to define how the use of different diets can influence the outcomes of patients hospitalized for IBD.

Enteral nutrition for maintenance of remission in Crohn's disease

BACKGROUND

Prevention of relapse is a major issue in the management of quiescent Crohn's disease (CD). Current therapies (e.g. methotrexate, biologics, 6-mercaptopurine and azathioprine) may be effective for maintaining remission in CD, but these drugs may cause significant adverse events. Interventions that are effective and safe for maintenance of remission in CD are desirable.

OBJECTIVES

The primary objectives were to evaluate the efficacy and safety of enteral nutrition for the maintenance of remission in CD and to assess the impact of formula composition on effectiveness.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL, the Cochrane IBD Group Specialized Register and clinicaltrials.gov from inception to 27 July 2018. We also searched references of retrieved studies and reviews.

SELECTION CRITERIA

Randomised controlled trials (RCTs) including participants of any age with quiescent CD were considered for inclusion. Studies that compared enteral nutrition with no intervention, placebo or any other intervention were selected for review.

DATA COLLECTION AND ANALYSIS

Two authors independently screened studies for inclusion, extracted data and assessed methodological quality using the Cochrane risk of bias tool. The primary outcome was clinical or endoscopic relapse as defined by the primary studies. Secondary outcomes included anthropometric measures (i.e. height and weight), quality of life (QoL), adverse events, serious adverse events and withdrawal due to adverse events. We calculated the risk ratio and 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated the mean difference and 95% CI. A random-effects model was used for the statistical analysis. We used the GRADE criteria to assess the overall certainty of the evidence supporting the primary outcome and selected secondary outcomes.

MAIN RESULTS

Four RCTs (262 adult participants) met the inclusion criteria. One study (N = 33) compared an elemental diet to a non-elemental (polymeric) diet. One study (N = 51) compared a half elemental diet to a regular free diet. Another study (N = 95) compared an elemental diet to 6-mercaptopurine (6-MP) or a no treatment control group. One study (N= 83) compared a polymeric diet to mesalamine. Two studies were rated as high risk of bias due to lack of blinding or incomplete outcome data. The other two studies were judged to have an unclear risk of bias. The studies were not pooled due to differences in control interventions and the way outcomes were assessed.The effect of an elemental diet compared to a polymeric diet on remission rates or withdrawal due to adverse events is uncertain. Fifty-eight per cent (11/19) of participants in the elemental diet group relapsed at 12 months compared to 57% (8/14) of participants in the polymeric diet group (RR 1.01, 95% CI 0.56 to 1.84; very low certainty evidence). Thirty-two per cent (6/19) of participants in the elemental diet group were intolerant to the enteral nutritional formula because of taste or smell and were withdrawn from the study in the first 2 weeks compared to zero participants (0/14) in the polymeric diet group (RR 9.75, 95% CI 0.59 to 159.93; low certainty evidence). Anthropometric measures, QoL, adverse events and serious adverse events were not reported as outcomes.The effect of an elemental diet (half of total daily calorie requirements) compared to a normal free diet on relapse rates is uncertain. Thirty-five per cent (9/26) of participants in the elemental diet group relapsed at 12 months compared to 64% (16/25) of participants in the free diet group (RR 0.54, 95% CI 0.30 to 0.99; very low certainty evidence). No adverse events were reported. This study reported no differences in weight change between the two diet groups. Height and QoL were not reported as outcomes.The effect of an elemental diet compared to 6-MP on relapse rates or adverse events is uncertain. Thirty-eight per cent (12/32) of participants in the elemental diet group relapsed at 12 months compared to 23% (7/30) of participants in the 6-MP group (RR 1.61; 95% CI 0.73 to 3.53; very low certainty evidence). Three per cent (1/32) of participants in the elemental diet group had an adverse event compared to 13% (4/30) of participants in the 6-MP group (RR 0.23, 95% CI 0.03 to 1.98; low certainty evidence). Adverse events in the elemental diet group included surgery due to worsening CD. Adverse events in the 6-MP group included liver injury (n = 2), hair loss (n = 1) and surgery due to an abscess (n = 1). No serious adverse events or withdrawals due to adverse events were reported. Weight, height and QoL were not reported as outcomesThe effect of a polymeric diet compared to mesalamine on relapse rates and weight is uncertain. Forty-two per cent (18/43) of participants in the polymeric diet group relapsed at 6 months compared to 55% (22/40) of participants in the mesalamine group (RR 0.76; 95% CI 0.49 to 1.19; low certainty evidence). The mean difference in weight gain over the study period was 1.9 kg higher in the polymeric diet group compared to mesalamine (95% CI -4.62 to 8.42; low certainty evidence). Two participants in the polymeric diet group experienced nausea and four had diarrhoea. It is unclear if any participants in the mesalamine group had an adverse event. Height, QoL, serious adverse events and withdrawal due to adverse events were not reported as outcomes.

AUTHORS' CONCLUSIONS

The results for the outcomes assessed in this review are uncertain and no firm conclusions regarding the efficacy and safety of enteral nutrition in quiescent CD can be drawn. More research is needed to determine the efficacy and safety of using enteral nutrition as maintenance therapy in CD. Currently, there are four ongoing studies (estimated enrolment of 280 participants). This review will be updated when the results of these studies are available.

Partially hydrolysed guar gum ameliorates murine intestinal inflammation in association with modulating luminal microbiota and SCFA

Partially hydrolysed guar gum (PHGG), a water-soluble dietary fibre produced by the controlled partial enzymatic hydrolysis of guar gum beans, has various physiological roles. This study aimed to elucidate the beneficial effects of PHGG on colonic mucosal damage in a murine 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model. Acute colitis was induced in male C57BL/6 mice with TNBS after 2 weeks of pre-feeding with PHGG (5 %). The colonic mucosal inflammation was evaluated using macroscopic damage scores, and neutrophil infiltration was assessed by measuring tissue-associated myeloperoxidase (MPO) activity in the colonic mucosa. TNF-α expression in the colonic mucosa was measured by ELISA and real-time PCR. Moreover, the intestinal microbiota and production of SCFA were assessed by real-time PCR and HPLC, respectively. Colonic damage due to TNBS administration was significantly ameliorated by PHGG treatment. Furthermore, PHGG significantly inhibited increases in MPO activity and TNF-α protein and mRNA expression in the colonic mucosa in TNBS-induced colitis. On analysis of intestinal microbiota, we found that the concentration of the Clostridium coccoides group (Clostridium cluster XIVa), the Clostridium leptum subgroup (Clostridium cluster IV) and the Bacteroides fragilis group had significantly increased in PHGG-fed mice. On analysis of SCFA, we found that the caecal content of acetic acid, propionic acid and butyric acid had significantly increased in PHGG-fed mice. Together, these results suggest that chronic ingestion of PHGG prevents the development of TNBS-induced colitis in mice by modulating the intestinal microbiota and SCFA, which may be significant in the development of therapeutics for inflammatory bowel disease.

Long-term therapeutic effectiveness of maintenance enteral nutrition for Crohn's disease

BACKGROUND

Long-term effectiveness of enteral nutrition for maintaining remission in pediatric Crohn's disease (CD) is poorly documented. The aim of this study was therefore to examine the long-term effectiveness of enteral nutrition with aminosalicylates as maintenance therapy for those in whom remission was primarily induced by total parenteral nutrition or exclusive enteral nutrition with aminosalicylates.

METHODS

We retrospectively analyzed data for 58 pediatric patients with newly diagnosed CD during a median follow-up period of 50 months (range, 12-216 months). Data for remission-induced patients in whom enteral nutrition with aminosalicylates was used as maintenance therapy were analyzed with particular reference to time to first relapse and time to first intestinal surgery.

RESULTS

Twenty-five (43.1%) of the patients relapsed with a median duration of remission of 32.4 months (range, 6-73.2 months). The cumulative rates of continuous remission were 0.88 (95%CI: 0.79-0.96) at 1 year, 0.73 (95%CI: 0.61-0.85) at 2 years, and 0.52 (95%CI: 0.35-0.68) at 5 years. None of the patients received corticosteroids, immunomodulators or anti-tumor necrosis factor agents until relapse. Disease location had no impact on timing of relapse, but with regard to disease behavior there was a trend towards earlier relapse in patients with penetrating type. Only six of the 58 patients (10.3%) needed intestinal surgery. There was a trend towards need for surgery in patients with ileal disease and with stricturing type.

CONCLUSIONS

Enteral nutrition therapy with aminosalicylates is effective for maintaining remission and decreasing the rate of intestinal surgery in pediatric CD.

Dietary patterns and self-reported associations of diet with symptoms of inflammatory bowel disease

BACKGROUND

There are insufficient data to make firm dietary recommendations for patients with inflammatory bowel disease (IBD). Yet patients frequently report that specific food items influence their symptoms. In this study, we describe patients' perceptions about the benefits and harms of selected foods and patients' dietary patterns.

METHODS

CCFA Partners is an ongoing internet-based cohort study of patients with IBD. We used a semi-quantitative food frequency questionnaire to measure dietary consumption patterns and open-ended questions to elicit responses from patients about food items they believe ameliorate or exacerbate IBD. We categorized patients into four mutually exclusive disease categories: CD without an ostomy or pouch (CD), UC without an ostomy or pouch (UC), CD with an ostomy (CD-ostomy), and UC with a pouch (UC-pouch).

RESULTS

Yogurt, rice, and bananas were more frequently reported to improve symptoms whereas non-leafy vegetables, spicy foods, fruit, nuts, leafy vegetables, fried foods, milk, red meat, soda, popcorn, dairy, alcohol, high-fiber foods, corn, fatty foods, seeds, coffee, and beans were more frequently reported to worsen symptoms. Compared to CD patients, CD-ostomy patients reported significantly greater consumption of cheese (odds ratio [OR] 1.56, 95 % CI 1.03-2.36), sweetened beverages (OR 2.14, 95 % CI 1.02-1.03), milk (OR 1.84, 95 % CI 1.35-2.52), pizza (OR 1.57, 95 % CI 1.12-2.20), and processed meats (OR 1.40; 95 % CI 1.04-1.89).

CONCLUSIONS

Patients identified foods that they believe worsen symptoms and restricted their diet. Patients with ostomies ate a more liberal diet. Prospective studies are needed to determine whether diet influences disease course.

Impacts of long-term enteral nutrition on clinical and endoscopic disease activities and mucosal cytokines during remission in patients with Crohn's disease: a prospective study

BACKGROUND

Long-term enteral nutrition may maintain clinical and endoscopic remission in patients with Crohn's disease (CD). The aim of this prospective study was to investigate the impacts of long-term enteral nutrition on clinical and endoscopic disease activities and mucosal tissue cytokines in patients with quiescent CD.

METHODS

Forty patients with CD who achieved clinical remission were included. Of these, 20 received continuous elemental diet (Elental) infusion during the nighttime and a low-fat diet during the daytime (EN group) and 20 received neither nutritional therapy nor food restriction (non-EN group). With these regimens, all 40 patients were monitored for 1 year. Further, ileocolonoscopy was performed at entry, at 6 and 12 months, and mucosal biopsies were taken for cytokine assays.

RESULTS

On an intention-to-treat basis, 5 patients (25%) in the EN group and 13 (65%) in the non-EN group had a clinical relapse during the 1-year observation (P = 0.03). The mean endoscopic inflammation (EI) scores were not significantly different between the groups at both entry and 6 months, but at 12 months EI scores were significantly higher in the non-EN group than in the EN group (P = 0.04). Additionally, the mucosal tissue interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha levels significantly increased with time in the non-EN group (entry versus 12 months, IL-1beta, P = 0.02; IL-6, P = 0.002; TNF-alpha, P = 0.001). In the EN group these cytokines did not show a significant increase.

CONCLUSIONS

Long-term enteral nutrition in patients with quiescent CD has a clear suppressive effect on clinical and endoscopic disease activities and the mucosal inflammatory cytokine levels.

Enteral nutrition for maintenance of remission in Crohn's disease

BACKGROUND

Prevention of relapse is a major issue in the management of Crohn's disease. Corticosteroids and 5-ASA preparations are not effective for the maintenance of remission. Methotrexate, infliximab, 6-mercaptopurine and its prodrug, azathioprine may be effective in maintaining remission, but these drugs may cause significant adverse events.

OBJECTIVES

To conduct a systematic review to evaluate the efficacy of enteral nutrition for the maintenance of remission in Crohn's disease.

SEARCH STRATEGY

MEDLINE (1966 to January 2007), EMBASE (1984 to January 2007) the Cochrane Central Register of Controlled Trials from the Cochrane Library (Issue 4, 2006) and the IBD/FBD Review Group Specialized Trials Register were searched. The articles cited in each publication were hand searched.

SELECTION CRITERIA

Randomised controlled trials which compared enteral nutrition with no intervention, placebo or with any other intervention were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of methodological quality of included studies were independently performed by two authors. The main outcome measure was the occurrence of clinical or endoscopic relapse as defined by the primary studies. Odds ratios and 95% confidence intervals were calculated for dichotomous outcomes.

MAIN RESULTS

Two studies were identified that met the inclusion criteria and were included in the review. Statistical pooling of the results of these studies was not possible because the control interventions, and the way outcomes were assessed differed greatly between the two studies. In one study (Takagi 2006), patients who received half of their total daily calorie requirements as elemental diet and the remaining half by normal diet had a significantly lower relapse rate compared to patients who received unrestricted normal diet (9 of 26 versus 16 of 25; OR 0.3, 95% CI 0.09 to 0.94). In the other study (Verma 2001), elemental and polymeric feeds (providing between 35 and 50% of patients' pretrial calorie intake in addition to unrestricted normal food) were equally effective for maintenance of remission and allowing withdrawal of steroid therapy (8 of 19 versus 6 of 14; OR 0.97, 95% CI 0.24 to 3.92).

AUTHORS' CONCLUSIONS

The available evidence suggests that supplementary enteral nutritional may be effective for maintenance of remission in Crohn's disease. Whilst larger studies are needed to confirm these findings, enteral nutritional supplementation could be considered as an alternative or as an adjunct to maintenance drug therapy in Crohn's disease.

Moderate Dietary Temperance Effectively Prevents Relapse of Crohn Disease

The authors examined the influence of diet (dietary fat intake and dietary temperance) on relapse of patients with Crohn disease. A 1-year prospective study of 76 patients with Crohn disease was conducted. The criterion for eligibility was a Crohn Disease Activity Index score of 150 or lower for at least 1 month. The primary end point was defined as the relapse-free interval from the baseline until the first relapse. Fat intake was assessed using a validated diet history questionnaire. The degree of dietary temperance was assessed using a single-item nominal scale. The Cox proportional hazards model was used to evaluate the influence of diet. Crohn disease relapse was seen in 25 patients (33%), and 47 patients (62%) remained in continuous remission. A decreased ratio of n-6 polyunsaturated fatty acid (PUFA) to n-3PUFA (odds ratio = .38; p = .005) was associated with a poor prognosis. Dietary temperance also was significantly associated with prognosis (p = .014). More moderate dietary temperance decreased the risk of relapse (odds ratio = .22; p = .006). Effective prevention of relapse for Crohn disease patients might be achieved through moderate dietary temperance, particularly when the disease condition is unstable.

Nutritional modulation of the inflammatory response in inflammatory bowel disease- From the molecular to the integrative to the clinical

Nutrient deficiencies are common in patients with inflammatory bowel disease (IBD). Both total parenteral and enteral nutrition provide important supportive therapy for IBD patients, but in adults these are not useful for primary therapy. Dietary intervention with omega-3 polyunsaturated fatty acids contained in fish oil may be useful for the care of IBD patients, and recent studies have stressed the role of PPAR on NFκB activity on the potential beneficial effect of dietary lipids on intestinal function.

Inflammatory bowel disease and the eye

Inflammatory bowel disease includes Crohn's disease and ulcerative colitis, and is characterized by chronic inflammation of the intestines. The advances in understanding of the inflammatory process have resulted in improved treatment of inflammatory bowel disease. The systemic complications of inflammatory bowel disease involve many organs, eyes included. The ophthalmic complications are usually of inflammatory origin. Some of these complications, like scleritis, may reflect overall disease activity. Treatment of intestinal inflammation-either medical or surgical-usually helps resolution of ophthalmic complications. This review describes recent developments in the diagnosis and management of the inflammatory bowel disease and its ophthalmic complications.

Inflammatory bowel diseases: principles of nutritional therapy

Inflammatory Bowel Diseases - ulcerative colitis and Crohn's disease- are chronic gastrointestinal inflammatory diseases of unknown etiology. Decreased oral intake, malabsorption, accelerated nutrient losses, increased requirements, and drug-nutrient interactions cause nutritional and functional deficiencies that require proper correction by nutritional therapy. The goals of the different forms of nutritional therapy are to correct nutritional disturbances and to modulate inflammatory response, thus influencing disease activity. Total parenteral nutrition has been used to correct and to prevent nutritional disturbances and to promote bowel rest during active disease, mainly in cases of digestive fistulae with high output. Its use should be reserved for patients who cannot tolerate enteral nutrition. Enteral nutrition is effective in inducing clinical remission in adults and promoting growth in children. Due to its low complication rate and lower costs, enteral nutrition should be preferred over total parenteral nutrition whenever possible. Both present equal effectiveness in primary therapy for remission of active Crohn's disease. Nutritional intervention may improve outcome in certain individuals; however, because of the costs and complications of such therapy, careful selection is warranted, especially in patients presumed to need total parenteral nutrition. Recent research has focused on the use of nutrients as primary treatment agents. Immunonutrition is an important therapeutic alternative in the management of inflammatory bowel diseases, modulating the inflammation and changing the eicosanoid synthesis profile. However, beneficial reported effects have yet to be translated into the clinical practice. The real efficacy of these and other nutrients (glutamine, short-chain fatty acids, antioxidants) still need further evaluation through prospective and randomized trials.

Fiber-rich diets alter rat intestinal leukocytes metabolism

This study addressed the following question: What is the effect of fermentable and nonfermentable fiber-rich diets on intestinal immune cells' function and metabolism? For this purpose, weaning rats received, for 8 weeks, two types of fiber-enriched (30%) diets with different fermentable/nonfermentable fiber ratios, that is, oat bran (0.3) and wheat bran (0.14). The results of these two experimental groups were compared with those of the low-fiber control group having a 0.22 fermentable/nonfermentable fiber ratio. The total number and proportion of leukocytes in plasma, total number of cells in the lymphoid organs, lymphocyte proliferative activity and capacity of phagocytosis, hydrogen peroxide production, and adherence of macrophages were investigated. The activities of key enzymes of glycolysis and glutaminolysis, and of the Krebs cycle of lymphocytes from the mesenteric lymph nodes and macrophages from the intraperitoneal cavity were determined. The metabolic response of lymphocytes and macrophages from rats fed the three diets to Bacillus Calmette-Guérin-stimulus was also investigated. The number of lymphocytes in the mesenteric lymph nodes was lower in both fiber-rich diets than in the control but did not have any difference in the remaining lymphoid organs. Wheat bran caused a significant reduction in the phagocytosis capacity and adherence index of macrophages, whereas oat bran did not have a significant effect. The response of glucose and glutamine metabolism to Bacillus Calmette-Guérin-stimulus was not altered by the diets in lymphocytes, whereas in macrophages, the increase in glutaminase and hexokinase activities was abolished.

Medical options for treating Crohn's disease in adults: focus on antitumor necrosis factor-alpha chimeric monoclonal antibody

Crohn's disease is a chronic inflammatory disorder that can present with symptoms throughout the gastrointestinal system. Though the etiology of Crohn's disease is unknown, genetic and environmental factors seem to play a role. An imbalance of proinflammatory versus antiinflammatory cytokines is responsible for many of the symptoms. Tumor necrosis factor alpha, a potent proinflammatory cytokine, plays a particularly important role. Several treatment modalities for Crohn's disease exist, recently including antitumor necrosis factor chimeric monoclonal antibody (cA2). Treatment for Crohn's disease, including data on the safety and efficacy of cA2, will be reviewed.

Medical therapy for inflammatory bowel disease

CD and UC represent a spectrum of chronic IBD that present in protean ways and are accompanied by a variety of systemic sequelae. Sulfasalazine and the newer 5-aminosalicylates are important in the management of mild-to-moderate disease, whereas corticosteroids remain the primary therapy for most patients with moderate-to-severe disease (Tables 2-5). The toxicities associated with long-term steroid therapy, combined with their ineffectiveness as maintenance medications, have led to increased use of immunomodulators, such as azathioprine and 6-MP, for the treatment of steroid-dependent and steroid-resistant IBD. Infliximab is a novel therapeutic adjunct for chronically active and fistulizing CD that will herald a new era of biologic therapy for IBD. Meanwhile, CSA remains an alternative to urgent colectomy in severe UC unresponsive to corticosteroids and also for CD patients with severe disease or refractory fistulas. Finally, continued insights into the etiopathogenic pathways in IBD will provide evolving and innovative approaches until the eventual causes and cures are elucidated. In the meantime, clinicians should remain optimistic regarding current ability to reduce the morbidity and maintain the quality of life for patients suffering with these frustrating diseases.

Gastrointestinal pH profiles in patients with inflammatory bowel disease

BACKGROUND

5-Amino salicylic acid preparations are used in therapy for patients with inflammatory bowel diseases. The bioavailability of these drugs depends on their coating.

AIM

To determine whether intraluminal pH is decreased by the presence of inflammation, thereby altering the release of 5-amino salicylic acid in the intestinal lumen.

METHODS

Intraluminal gastrointestinal pH was measured by means of a radiotelemetry capsule in 12 healthy controls, in 12 patients with Crohn's disease (five with active disease), and in 11 patients with ulcerative colitis (seven with active disease).

RESULTS

The median gastric pH values in the patient groups (Crohn's disease 2.4, range 1.5-4.1; ulcerative colitis 1.95, range 1.55-4.4) were significantly higher than those observed in the controls (1.55, range 0.95-2.6). In the small bowel and colonic segments, all the pH values of Crohn's disease patients were comparable to those of the controls, as were the pH values in the proximal small intestine and in the left colon in patients with ulcerative colitis. However, the latter group had higher pH values in the terminal ileum, the caecum and the right colon. Patients with active disease had comparable median gastrointestinal pH values to patients in remission.

CONCLUSIONS

The luminal release of 5-amino salicylic acid might not be inhibited by low pH in patients with active inflammatory bowel diseases. This supports a safe disintegration of the slow release mesalazine preparations even in the presence of severe disease.

Appropriate nutritional support in acute and complicated Crohn's disease

Crohn's disease is frequently complicated by protein-calorie malnutrition. Four common clinical presentations of Crohn's disease include acute exacerbations or flares of disease, intestinal obstruction, fistulizing disease, and perianal disease. In this review, we examine the role of nutritional support in these clinical scenarios. Nutritional support is important for maintaining functional status and preventing loss of lean tissue. Determinants of lean-tissue loss include severity of underlying injury, baseline nutritional status, and duration of inadequate nutrition. One of the clinically useful measures of nutritional status is the nutritional risk index (NRI) defined on the basis of the serum albumin and weight loss. Nutritional support is important in severely malnourished patients (NRI < 83). Enteral nutrition is the route of choice, provided there are no contraindications to using the gastrointestinal tract. In acute exacerbations of Crohn's disease, enteral nutrition also has a role in the primary management of disease although it is not as effective as corticosteroids in inducing remission. The mechanisms are poorly understood and the most effective enteral formulation needs to be determined. Total parenteral nutrition is justified in severely malnourished Crohn's disease patients who are unable to tolerate enteral feeding or in whom enteral feeding is contraindicated. More clinical studies are needed on the assessment of malnutrition in Crohn's disease, the effects of nutritional management on functional status, and the timing of nutritional intervention.

Review article: the dietary management of Crohn's disease

Enteral feeding has been shown to be as effective as primary therapy for Crohn's disease, but it requires high patient motivation, may be unpalatable and is expensive. However, in adolescents with growth failure and when corticosteroid therapy is contra-indicated or has failed, it may become the treatment of choice. Furthermore, dietary therapy allows circumvention of the adverse side-effects of repeated courses of steroids. A number of different hypotheses have been proposed to explain the effect of enteral feeds but none has reached universal acceptance. Prospective trials suggest that the exclusion of whole protein is not necessary. Comparison of feeds with differing composition suggests that a low fat content increases efficacy and various explanations have been offered. The reduction of colonic bacterial load may also be important. Because symptoms of Crohn's disease may be provoked by eating, there is a risk of falsely attributing symptoms to specific foodstuffs. However, in many individuals foods can be identified which affect disease activity, and their exclusion leads to prolongation of disease remission. Dietetic supervision during food testing is important to avoid detrimental effects on nutrient and micronutrient intake.