What foods should be avoided before a colonoscopy?

Foods to Avoid Before a Colonoscopy

For optimal bowel preparation before a colonoscopy, patients should follow a low-residue/low-fiber diet on the day before the procedure, avoiding high-fiber foods such as cereals, beans, peas, nuts, seeds, and raw or dried fruits and vegetables. 1

Dietary Recommendations Timeline

One Day Before Colonoscopy (Most Important)

• Limit dietary modifications to the day before colonoscopy for patients at low risk for inadequate bowel preparation 1
• Follow a low-residue/low-fiber diet for early and midday meals 1
• Avoid the following specific foods:
  • Red meat and poultry 2
  • Vegetables 2
  • High-fiber foods (cereals, beans, peas, nuts, seeds) 1
  • Raw or dried fruits and vegetables 1
• Recommended foods to consume:
  • Gelatin (has been positively associated with better bowel preparation quality) 2
  • Clear liquids (especially later in the day) 3

Iron Supplementation

• Discontinue iron supplements at least 7 days before colonoscopy 4
• Iron can cause dark, sticky stool that adheres to colonic mucosa, making visualization difficult 4
• Iron residue can obscure detection of polyps and lesions, potentially compromising diagnostic accuracy 4

Special Considerations

Risk Factors for Inadequate Bowel Preparation

• Medical conditions that increase risk of poor preparation include:
  • Cirrhosis (OR 3.4) 1
  • Parkinson disease (OR 3.2) 1
  • Dementia (OR 3.0) 1
  • Diabetes (OR 1.8) 1
  • Constipation (OR 1.3) 1

Evidence on Dietary Restrictions

• Additional days of dietary restrictions beyond one day before colonoscopy confer no benefit in bowel preparation adequacy 1
• Patients find 1-day diet restriction more tolerable and easier to comply with compared to longer durations 1
• Recent studies show that a normocaloric low-fiber diet the day before colonoscopy achieves better results than a clear-liquid diet in terms of adequate colon preparation 3

Common Pitfalls to Avoid

• Unnecessarily restricting diet for more than one day before colonoscopy, which can reduce compliance without improving outcomes 1
• Failing to discontinue iron supplements at least 7 days before the procedure 4
• Not providing clear instructions about specific foods to avoid (red meat, poultry, vegetables) on the day before colonoscopy 2
• Overlooking the positive impact of gelatin consumption on the day before the procedure 2

Practical Approach

• Focus dietary restrictions on the day before colonoscopy only 1
• Early/midday meals: low-residue/low-fiber foods 1
• Evening before: clear liquids only 3
• Ensure patients understand to avoid red meat, poultry, and vegetables specifically on the day before the procedure 2
• Encourage consumption of gelatin to improve bowel preparation quality 2