What to Eat Before a Colonoscopy for the Best Clean Out
Key takeaways:
A good colonoscopy prep (or bowel clean out) is critical for an accurate colonoscopy.
What you eat in the days before your colonoscopy can impact how thorough your bowel clean out is.
The best foods to eat before a colonoscopy include low-fiber foods, low-residue foods, and clear liquids.
Foods to avoid before a colonoscopy include seeds and foods or drinks with red or purple dye.
The U.S. Preventive Task Force recommends adults with an average risk of colorectal cancer to get screened for colon cancer starting at age 45. That’s because colon cancer is the third most common cancer in the U.S.
A colonoscopy is a screening for colon cancer. During a colonoscopy, a gastroenterologist looks at your colon using a camera. The camera is inserted into your colon through a tube that enters through the anus.
What is colonoscopy prep?
Before your colonoscopy, you’ll have to do a colonoscopy prep — sometimes called a bowel clean out. The prep can make or break a colonoscopy. It will greatly help the specialist doing the procedure, usually a gastroenterologist. The better the clean out, the better they’ll be able to see your colon. And this allows you to get the best and most accurate results.
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If you don’t follow the prep thoroughly, the specialist may not be able to see your colon. This means you won’t get any results, and you might have to get a repeat colonoscopy.
Colonoscopy prep involves taking medications to remove stool from your bowels. The medications speed up how quickly stool moves through your bowel. But just taking your medication isn’t enough. You also have to adjust your diet in the days leading up to your colonoscopy.
Before your colonoscopy, you’ll follow specific instructions from your care team. But read on for some general guidelines for what foods you should and shouldn’t eat before your colonoscopy.
What to eat before a colonoscopy
Some foods are better to eat than others in the days leading up to your colonoscopy. These foods can impact how thorough your bowel clean out is.
Low-fiber foods
Fiber provides many health benefits, and high-fiber foods are great to include in your regular diet. But it’s important to avoid high-fiber foods in the days before a colonoscopy. This is because they’re likely to leave undigested material behind in your colon. This will make your colonoscopy prep less effective.
It’s best to opt for low-fiber foods, like:
Dairy products
Lean meats
Fish
Tofu
Creamy peanut butter
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Low-residue foods
“Residue foods” are foods that leave behind material in the colon after digestion. Fiber is one type of residue. But there are other foods that can leave behind residue. For example, dairy products don't contain fiber, but they can contribute to residue.
A low-residue diet can help clear the colon before your procedure. In the long term, eating low-residue foods can lead to constipation. But, in the short term, it can help you achieve a better clean out before your colonoscopy.
It’s best to incorporate low-residue foods into your diet for 3 to 5 days before your colonoscopy. Examples of low-residue foods include:
Eggs
White rice
Refined grain products (like white bread)
Fruits without seeds or skin (like bananas or peeled apples)
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Clear liquids
Some healthcare professionals will ask you to follow a clear liquid diet for 24 hours before your colonoscopy. Clear fluids allow you to stay hydrated while your diet is restricted. So, make sure to drink or eat plenty of clear liquids the day before your colonoscopy.
Choose clear liquids like:
Clear broth
Plain Jell-O (without red or purple food dye — more on this below)
Popsicles (avoid red or purple versions)
Gatorade (not red or purple)
Pulp-free fruit juice, like apple or white grape juice
What not to eat before a colonoscopy
Certain foods make your bowel clean out easier, but others make it more difficult. Avoid the following foods, which can impact your colonoscopy prep and affect your results.
Red and purple food dyes
Red or purple foods or dyes can leave behind a reddish color in your colon. This can be mistaken for blood, which will prompt the healthcare professional to take tissue samples. So avoid any foods or drinks that contain red or purple dye for 48 hours before your colonoscopy.
Popcorn, nuts, and seeds
Stop eating popcorn, seeds, and nuts at least a week before your colonoscopy. The hull (outer part) of popcorn, nuts, or seeds can stay in your colon for several days. These items can make it difficult for the specialist to see the lining of the colon. These foods can also block the opening of the colonoscope. This can break the colonoscope. And that means you — and everyone else scheduled that day — won’t be able to get a colonoscopy.
Make sure to avoid not only whole nuts but crushed nuts as well, including chunky nut butters.
Fruits or vegetables with skin
The skins of vegetables and fruits are very high in fiber. And high-fiber foods are a no-go in the days leading up to a colonoscopy. It can be tricky to spot fruits and vegetables that have skins. Some are obvious, like pears and kiwis. But others may surprise you.
Here are some fruits and vegetables to avoid:
Berries
Raisins and other dried fruits
Corn
Tomatoes
Green peas
Cabbage
Brussels sprouts
High-fiber foods
For 3 to 5 days before your colonoscopy, it’s best to avoid foods high in fiber, including:
Nuts and seeds
Whole fruit
Frequently asked questions
Many people are instructed to follow a clear liquid diet beginning the day before their colonoscopy. Giving up solid food for 24 to 36 hours isn't easy. But it helps to remember that it’s only temporary.
The best way to curb hunger during a clear liquid diet is to be prepared. This means having a variety of allowable liquids on hand, including:
Clear juices (like apple) and light-colored popsicles and gelatins (like Jell-o), which provide hydration and sugar
Clear broth, like chicken broth and beef broth, which are helpful savory options
Gummy bears, which can keep the mouth busy. Just be sure to avoid red and purple ones.
Black coffee or tea (without milk or cream) are very helpful if you’re used to having these beverages as part of your daily routine.
You’ll know your colon has been cleared out thoroughly once your stool comes out clear or yellowish, like urine. If you see particles or murky liquid in your stool, it’s possible your colon isn’t completely emptied out. If it’s time for your appointment and you think your colon may not be thoroughly cleared out, it’s a good idea to check in with your healthcare team.
The bottom line
What you eat before a colonoscopy can impact your results. For the best colonoscopy prep, stick with low-fiber and low-residue foods for 3 to 5 days before your colonoscopy. Eggs, dairy, white bread, and lean meats are a few examples of low-fiber, low-residue foods. Avoid nuts, seeds, and foods/drinks with red or purple dyes. These foods might interfere with the accuracy of your procedure.
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References
American Cancer Society. (2025). Key statistics for colorectal cancer.
D’Ambrosio, A. (2013). Low residue diet. Gastrointestinal Society.
Kaiser Permanente. (n.d.). Clear-liquid diet for colonoscopy preparation.
Kaiser Permanente. (n.d.). Low-fiber diet for colonoscopy preparation.
Saltzman, J. R., et al. (2015). Bowl preparation before colonoscopy. Gastrointestinal Endoscopy.
Shah, N. D., et al. (2015). Low residue vs. low fiber diets in inflammatory bowel disease: Evidence to support vs. habit? Practical Gastroenterology.
U.S. Preventive Services Task Force. (2021). Colorectal cancer: Screening.
Vanhauwaert, E., et al. (2015). Low-residue and low-fiber diets in gastrointestinal disease management. Advances in Nutrition.
Zainab, M., et al. (2013). Red color colonoscopy prep does not affect endoscopic visualization: A pilot study. The American Journal of Gastroenterology.
