How long before a colonoscopy should tomatoes be stopped?

Tomatoes Should Be Stopped 2-3 Days Before Colonoscopy

Patients should restrict the intake of tomatoes and other vegetables for 2 to 3 days before colonoscopy to optimize bowel preparation quality. 1

Understanding Dietary Restrictions for Colonoscopy

The quality of bowel preparation is critical for a successful colonoscopy, as inadequate preparation can lead to:

• Missed lesions, including adenomas and advanced adenomas
• Need for repeat procedures
• Increased procedure time
• Reduced detection rates for colorectal cancer

Timing of Dietary Restrictions

The US Multi-Society Task Force on Colorectal Cancer provides clear guidance on dietary restrictions before colonoscopy:

• 2-3 days before colonoscopy: Restrict intake of vegetables (including tomatoes) and legumes 1
• Day before colonoscopy: Follow either low-residue diet or clear liquids, depending on risk factors 1
• Day of colonoscopy: Nothing except the bowel preparation solution and clear liquids up to 2 hours before the procedure 1

Why Tomatoes Should Be Restricted

Tomatoes should be restricted because:

1. They contain seeds and skins that are difficult to digest
2. They are considered vegetables in dietary context (botanically they're fruits)
3. They contribute to residue in the colon that can interfere with visualization

Research has shown that vegetables consumed 2-3 days before colonoscopy can negatively impact bowel preparation quality 1, 2. A prospective study using food diaries confirmed that foods consumed 2-3 days before colonoscopy can affect bowel preparation quality, with vegetables being specifically identified as problematic when consumed the day before colonoscopy 2.

Complete Dietary Protocol for Optimal Colonoscopy Preparation

For best results, follow this evidence-based protocol:

2-3 Days Before Colonoscopy:

• Restrict: Tomatoes, other vegetables, legumes, nuts, seeds, and high-fiber foods 1
• Allowed: Low-residue foods (white bread, white rice, lean proteins, etc.)

Day Before Colonoscopy:

• Avoid: Red meat, poultry, vegetables (including tomatoes) 2
• Recommended: Clear liquids, gelatin (which is positively associated with better preparation) 2
• Follow: Split-dose bowel preparation regimen as prescribed 1

Day of Colonoscopy:

• Continue: Clear liquids up to 2 hours before procedure 1
• Complete: Second portion of split-dose preparation 4-6 hours before colonoscopy, finishing at least 2 hours before the procedure 1

Common Pitfalls to Avoid

1. Inadequate restriction of vegetables: Many patients don't realize that tomatoes count as vegetables for dietary restriction purposes
2. Poor compliance with dietary instructions: Only 17% of patients fully comply with diet restrictions 2 days before colonoscopy 2
3. Focusing only on the day before: The 2-3 day period before colonoscopy is equally important for preparation quality

Special Considerations

For patients with a history of poor bowel preparation, even stricter dietary measures may be necessary:

• Extended clear liquid diet (entire day before procedure)
• More aggressive restriction of vegetables and high-fiber foods
• Additional bowel preparation medications 1

The goal is to achieve a bowel preparation adequacy rate of 90%, which is the recommended benchmark by the US Multi-Society Task Force 1. Following these dietary guidelines, including stopping tomatoes 2-3 days before colonoscopy, will help achieve this goal and ensure optimal visualization during the procedure.