Low-Fiber Diet Before a Colonoscopy: What to Eat and Avoid

01Why

Why diet matters before a colonoscopy

During a colonoscopy, the doctor examines the lining of the large bowel to look for polyps, inflammation, bleeding and cancer. Stool, seeds and food residue can hide lesions, so poor bowel preparation increases the risk of a missed polyp and may require the procedure to be repeated. A low-fibre diet reduces the amount of residue that the bowel preparation must clear. See also high-fibre foods.

02Timeline

Typical timeline

• 5–7 days before: some clinics ask you to stop iron tablets, fibre supplements and certain medicines; check with your clinic.
• 1–3 days before: low-fibre (low-residue) diet; avoid seeds, nuts, popcorn, whole grains, raw vegetables and fruit skins.
• The day before: clear liquids only (some clinics allow a light low-fibre breakfast), then the bowel preparation drink in one or two doses.
• The morning of the procedure: the second dose of preparation (usually several hours before) and nothing by mouth for the time stated by your clinic.
• Timing differs between clinics and preparations: use your own instructions.

03Eat

Foods you can eat on a low-fibre diet

• Grains: white bread, white rice, plain pasta, refined cereals such as cornflakes or rice cereal, plain crackers.
• Protein: eggs, tender chicken, turkey, fish, lean tender meat, tofu, smooth peanut butter (small amounts).
• Dairy: milk, plain yoghurt without seeds or fruit pieces, cheese.
• Vegetables: well-cooked, peeled, seedless: carrots, potatoes without skin, courgette, pumpkin; vegetable juice without pulp.
• Fruit: bananas, melon, canned or cooked peeled fruit without seeds, apple sauce, fruit juice without pulp.
• Fats and others: butter, oils, mayonnaise, clear soups, broth, gelatin, honey, plain biscuits.

04Avoid

Foods to avoid

• Whole grains: whole wheat bread, brown rice, oats, bran, multigrain products.
• Nuts, seeds (including in bread and fruits such as strawberries, tomatoes and kiwi), popcorn and chunky nut butters.
• Raw vegetables and salads; corn, peas, broccoli, cabbage, onions, peppers and skins.
• Dried fruit, berries and fruit with skin or seeds, and juice with pulp.
• Legumes: beans, lentils, chickpeas.
• Tough, fatty or processed meats; fried food.
• Red and purple liquids or foods (they can resemble blood during the exam), if your clinic asks for it.
• Alcohol.

05Clear liquids

The clear-liquid day

Clear liquids are liquids you can see through. Choices include water, clear broth or bouillon, apple or white grape juice without pulp, clear soda, sports drinks, tea or black coffee without milk, plain gelatin and ice pops (without fruit pieces or cream). Avoid red or purple colours and anything with milk, pulp or solid pieces. Drink plenty, because the preparation causes fluid loss. Follow your clinic’s guidance on the allowed time to stop drinking before the procedure.

06Menu

Sample low-fibre menu

• Breakfast: scrambled eggs, white toast with butter, a banana, milk or tea.
• Lunch: chicken or fish with white rice and peeled boiled carrots; canned peaches.
• Snack: plain yoghurt, white crackers and smooth cheese.
• Dinner: plain pasta with a mild tomato-free sauce and tender turkey; applesauce.
• Adjust to your clinic’s list and any medical diet.

07Medicines

Medicines and special situations

• Diabetes: medicine doses may need adjusting during the preparation and fasting; talk to your doctor.
• Blood thinners and antiplatelets: your clinic will advise whether and when to stop them.
• Iron tablets and fibre supplements: often stopped several days beforehand.
• Heart, kidney or electrolyte problems: certain preparations are not suitable; ask for an appropriate one.
• Constipation: may need an extended preparation.
• Pregnancy and older adults: require individual advice.
• Never stop essential medicines (such as for blood pressure or epilepsy) unless instructed.

08Tips

Tips for a successful preparation

• Read the instructions as soon as you receive them and plan ahead.
• Chill the preparation solution and drink it through a straw to make it easier.
• Stay close to a toilet and use barrier cream to prevent skin irritation.
• Keep hydrated, and have a clear liquid after each dose if allowed.
• Suck on lemon or boiled sweets between doses if the taste is unpleasant (without red dye).
• Do not eat solid food after starting the clear-liquid phase.
• Arrange transport and time off as the procedure is usually done under sedation.

09Doctor

When to call the clinic

• Unable to complete the preparation or vomiting repeatedly.
• Severe abdominal pain, bloating or dizziness.
• Signs of dehydration: dark urine, extreme thirst, fainting.
• You are unsure about medicines or diabetes management.
• You have eaten something not allowed shortly before the exam: the procedure may need to be rescheduled.

10Cases

Three common situations

A person with constipation: may need extra laxatives or a longer preparation; ask the clinic.

A person with diabetes: plan insulin or tablets with the clinic to avoid hypoglycaemia during fasting.

A person who ate seeds the day before: tell the clinic; they may advise continuing, or rescheduling if the bowel is not clean.

11Summary

Key points to remember

A low-fibre diet followed by clear liquids and a full bowel preparation gives the clearest view during colonoscopy. Follow your clinic’s instructions to the letter, ask about medicines and call if problems arise. Our nutrition team can help you plan the diet.

This guide is for general information and does not replace an assessment by your own doctor, speech-language pathologist or dietitian.