A colonoscopy is used to detect colon abnormalities, growths and cancer. Your colon must be as clear as possible for an accurate assessment. Colonoscopy preparation involves following a special diet and taking laxatives to clear your large bowel. Depending on the bowel preparation regimen your doctor recommends, you will likely be asked to consume only clear liquids for a period of time. Flavored gelatins, such as JELL-O, are permitted on a clear liquid diet -- but certain colors should be avoided.
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Always check with your doctor or testing facility about whether specific foods should be avoided before your colonoscopy. In general, however, only certain colors of gelatin are allowed. Most colonoscopy testing facilities recommend only eating yellow or green gelatin. Red, orange, purple and sometimes blue gelatins are usually not permitted during the bowel preparation for a colonscopy as the food dye in these varieties may interfere with the test.
Red, orange, purple and some blue gelatin flavors contain red food dye, which may cause residual red fluid in the colon that can easily be mistaken for blood during a colonoscopy. This is an important concern, as it could cause the doctor to search for bleeding when there isn't any. Bleeding is a critical consideration during a colonoscopy, especially if the doctor takes biopsies of the colon. Eating the wrong foods prior to the exam may render the results inconclusive, making a repeat procedure necessary.
Flavored gelatin can make a liquid diet less monotonous, as it offers a textural alternative to clear beverages and broth. Many varieties of JELL-O will be off limits because they're orange, red or purple, but you still have many flavor options, including lemon, lime, pineapple, apricot and mango. Check the ingredients listed on the package to be sure the variety you've chosen does not contain red food dye.
The avoidance of foods containing red dye goes beyond gelatin when you're preparing for a colonoscopy. You'll probably also be advised to avoid orange, red, purple and possibly blue ice pops, flavored beverages and sports drinks. If you're unsure whether a specific food or beverage is permitted during your bowel prep, call your doctor or testing facility so your procedure doesn't have to be postponed or repeated.
Reviewed by: Tina M. St. John, M.D.