What dietary recommendations should be given to an adult with inflammatory bowel disease (Crohn’s disease or ulcerative colitis) without comorbidities for both maintenance of remission and management of active flares?

Dietary Management of IBD

Core Dietary Principle

All adults with IBD should follow a varied, balanced diet based on healthy eating guidelines that includes a wide variety of fruits, vegetables, cereals, grains, nuts, seeds, and protein-rich foods, while moderating high-fat foods (particularly animal fat), high sugar items, and processed meats—non-evidence-based self-directed exclusion diets must be actively discouraged as they lead to nutritional deficiencies without clinical benefit. 1

General Dietary Framework for All IBD Patients

Base Diet Pattern

• Adopt a Mediterranean-style dietary pattern emphasizing fresh fruits and vegetables, whole grains, monounsaturated fats (especially olive oil), and lean proteins such as fish, poultry, and legumes 2
• Include dietary fiber as part of the varied diet, as no single dietary component can be attributed to causing relapses or ongoing symptoms 1
• Limit ultraprocessed foods, added sugars, salt, and red/processed meats 2
• Reduce red and processed meat consumption specifically, as this modification may lower the risk of flares, particularly in ulcerative colitis 2

Critical Caveat on "IBD Diets"

There is no single "IBD diet" that can be generally recommended to promote remission in patients with active disease. 1 Despite interest in specific carbohydrate diets, paleolithic diets, gluten-free diets, low-FODMAP diets, or omega-3 enriched diets, pooled RCT data show uncertain results or are lacking entirely 1. A recent Cochrane review including 18 RCTs found no firm conclusion could be drawn regarding benefits of any dietary intervention in UC or CD due to high heterogeneity 1.

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Disease-Specific Modifications

For Crohn's Disease with Strictures

• Limit dietary fiber and fibrous foods to prevent mechanical obstruction 1
• Consider texture-adapted diets or distal (post-stenosis) enteral nutrition 1
• Supplementation with enteral or parenteral nutrition may be required to meet energy and nutritional requirements 1
• Recommend thorough chewing of food and caution with fruit/vegetable skins, sweetcorn, celery, and nuts (smooth nut butters are acceptable) 1

For Active Crohn's Disease (Mild to Moderate)

• Crohn's Disease Exclusion Diet (CDED) plus partial enteral nutrition should be considered as an alternative to exclusive enteral nutrition in pediatric patients (Grade B recommendation) 1
• In adult patients, CDED can be considered with or without enteral nutrition, though evidence is less robust (Grade 0 recommendation) 1
• This approach combines specific whole foods with partial enteral nutrition and has shown effectiveness comparable to exclusive enteral nutrition in 12-week prospective RCTs with better tolerability 1

For Ulcerative Colitis (Mild to Moderate Active Disease)

• Probiotic therapy using Lactobacillus reuteri or VSL#3 (the specific formulation used in cited literature) can be considered for induction of remission 1, 2
• Probiotics should NOT be used for treatment of active Crohn's disease 1

For Functional Bowel Symptoms in Remission or Mildly Active Disease

• Consider dietary advice as for irritable bowel syndrome, such as a low-FODMAP diet 1
• This addresses concurrent functional symptoms (bloating, pain, flatulence) but does not reduce intestinal inflammation 2
• Low-FODMAP diets may negatively affect beneficial gut bacteria and should not be used as primary therapy for UC 2

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Nutritional Monitoring and Supplementation

Micronutrient Surveillance

• Vitamin D deficiency is extremely prevalent: 66% in Crohn's disease and 69% in UC, with severe deficiency in 27% and 36% respectively 1
• Monitor and supplement vitamin D in patients with active disease and those on steroids to prevent low bone mineral density 1
• Calcium supplementation should be considered alongside vitamin D, as up to one-third of IBD patients fail to meet recommended dietary calcium intake 1

Iron Management

• Intravenous iron should be considered first-line in patients with clinically active IBD, previous intolerance to oral iron, hemoglobin below 100 g/L, or those needing erythropoiesis-stimulating agents 1
• Follow existing ECCO guidelines for monitoring and management of iron, vitamin B12, and folate deficiency 1

Other Micronutrients

• Magnesium deficiency occurs in 13-88% of IBD patients due to increased gastrointestinal losses 1
• Symptoms include abdominal cramps, impaired healing, fatigue, and bone pain 1
• Oral magnesium supplementation can worsen diarrhea; intravenous administration may be preferred 1
• Monitor and supplement plasma potassium as required 1

Interpretation of Micronutrient Levels

• Serum micronutrient levels are influenced by disease activity and should be interpreted with CRP levels 1
• Reliable interpretation requires CRP <20 mg/L for plasma zinc, <10 mg/L for selenium/vitamin A/vitamin D, or <5 mg/L for vitamin B6/vitamin C 1

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Special Situations

Patients with Ileostomy

• Small, frequent, nutrient-dense meals/snacks with oral nutritional supplements where necessary 1
• Sodium: Add 0.5-1 teaspoon extra salt per day to prevent dehydration 1
• Potassium: Increase intake if serum levels are low (bananas, potatoes, potato crisps, spinach, fish, poultry, lean red meat, sweet potato, avocado) 1
• Fiber: High fiber intake increases loose stools, flatulence, and bloating 1
• Thickening output: Bananas, pasta, rice, white bread, mashed potato, marshmallows, or jelly 1
• Fluids: 2-2.5 liters per day, more during hot weather or exercise 1
• Avoid hypotonic drinks (tea, water) and hypertonic drinks (fruit juice) in excess as these increase stoma output and dehydration 1
• Encourage isotonic drinks (oral rehydration solutions, sports drinks) 1
• If ileostomy output exceeds one liter per day, recommend oral rehydration solution: 1 liter tap water with 6 level teaspoons glucose, 1 level teaspoon salt, half teaspoon sodium bicarbonate or sodium citrate 1
• Consider loperamide 1-2 tablets (2-4 mg) half hour before meals 1
• Monitor vitamin B12 1

Patients with Severe Diarrhea or High-Output Stoma

• Monitor fluid output and urine sodium 1
• Decrease hypotonic fluid and increase saline solutions 1
• Consider food intolerances that may enhance fluid output 1
• Parenteral infusions (fluid and electrolytes) may be needed for ongoing high-output stomas 1

Patients with Fat Malabsorption

• CD patients treated with bile acid sequestrants (colestyramine) have minimal additional risk of fat malabsorption and do not need different nutrition therapy 1
• IBD patients with hyperoxaluria often have concurrent fat malabsorption and should receive counseling 1

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Critical Implementation Pitfalls to Avoid

Avoid Inappropriate Restrictions

• Non-evidence-based self-directed exclusion diets must be actively discouraged as they lead to limited diet quality and nutrient deficiency 1
• Gluten avoidance is not indicated unless the patient has confirmed celiac disease or documented gluten sensitivity 2
• Routine fasting or NPO status is unnecessary for mild disease 2
• Fiber-rich foods should not be avoided in the absence of strictures 2

Ensure Professional Guidance

• All IBD patients should have access to a registered dietitian for individualized nutritional approach as part of multidisciplinary care 1, 2, 3
• Dietitians help differentiate necessary from unnecessary dietary restrictions, ensure adequate nutrient intake, and incorporate cultural food preferences 2
• Self-directed elimination diets without dietitian guidance lead to poor outcomes 1

Recognize When Diet Alone Is Insufficient

• Dietary modifications address symptoms and nutritional status but do not replace medical therapy for active inflammation 1
• If dietary measures fail to control symptoms after appropriate trial, escalate medical management rather than imposing further dietary restrictions 2