Red, blue, and purple dyes in gelatin, ice pops, or drinks can discolor the colon lining and make it harder for a doctor to see during a colonoscopy.
Notes on verification
Confirmed by multiple independent, reputable medical sources (MD Anderson, UnityPoint Health, GoodRx, Norton Healthcare, Fight Colorectal Cancer) that consistently advise avoiding red/purple/blue dyes before colonoscopy due to risk of mimicking blood or inflammation. [tier=unverified indep_score=0.3 clusters=5 claim_tier=notable] [rescored 2026-09-15: curated origin-host map (PR #65); unclassified hosts no longer scored as aggregators]
Sources
- How to Prepare for a Colonoscopy (seed:health_and_medicine)
- https://www.mdanderson.org/cancerwise/how-to-make-colonoscopy-prep-better.h00-159857712.html (corroboration)
- https://www.unitypoint.org/news-and-articles/colonoscopy-prep-questions-and-answers (corroboration)
- https://www.goodrx.com/health-topic/procedures/what-to-eat-before-colonoscopy (corroboration)
- https://nortonhealthcare.com/services-and-conditions/gastroenterology/treatment/liquid-diet/ (corroboration)
- https://fightcolorectalcancer.org/colonoscopy-prep-chocolate-bars-and-strawberry-smoothies/ (corroboration)