Foods to Avoid With Ulcerative Colitis: Flare and Remission

01Role

What diet can and cannot do in ulcerative colitis

UC is an inflammatory bowel disease in which the immune system attacks the lining of the colon. Food does not cause it and diet cannot replace medical treatment, but certain foods can irritate an inflamed bowel and trigger cramps, urgency and diarrhoea. Triggers differ between people and between flares and remission, so personalised advice is best. See gut healthy foods and bland diet foods.

02Avoid

Foods that commonly worsen symptoms during a flare

• High-fibre foods and rough textures: raw vegetables and salads, whole-grain bread, bran, brown rice, popcorn, nuts and seeds, fruit skins and seeds, dried fruit, corn.
• Legumes: beans, lentils, chickpeas, which can cause gas and cramps.
• Fatty and fried foods: fast food, fatty meats, creamy sauces, which speed up the gut.
• Spicy foods: chilli, hot sauces, curry.
• Caffeine, alcohol and carbonated drinks.
• Sugar alcohols and artificial sweeteners (sorbitol, mannitol, xylitol) in sugar-free products.
• Very sugary foods and drinks, including fruit juices in large amounts.
• Dairy if you are lactose intolerant; milk and ice cream can worsen diarrhoea.
• High-sulphur foods (some people report issues with processed meat, red meat, eggs and cruciferous vegetables).
• Ultra-processed foods, additives and emulsifiers, which some research links to inflammation.

03Eat

Foods that are usually better tolerated in a flare

• Refined grains: white rice, plain pasta, white bread, cornflakes, oatmeal (if tolerated).
• Cooked, peeled vegetables: carrots, courgette, squash, potatoes without skin.
• Peeled or cooked fruit: bananas, applesauce, canned peaches or pears, melon.
• Lean protein: eggs, fish, skinless poultry, tofu.
• Smooth nut butter in moderation.
• Low-fat yoghurt and lactose-free dairy, if tolerated.
• Soups, broths and well-cooked stews with soft ingredients.
• Oral nutritional supplements if appetite is poor.
• Eat small, frequent meals and drink plenty of fluids.

04Remission

Diet in remission

When symptoms settle, gradually reintroduce foods one at a time to avoid unnecessary restriction. Most people can eat a wide range of foods in remission, and a Mediterranean-style diet rich in vegetables, fruit, whole grains, legumes, olive oil and fish is generally recommended. Fibre from soft, cooked or soluble sources (oats, bananas, peeled apples) is usually tolerated first. Avoid long-term elimination of whole food groups without a dietitian, because it risks deficiencies.

05Nutri

Nutritional risks to watch

• Iron-deficiency anaemia from blood loss.
• Vitamin D and calcium deficiency, particularly with steroids.
• Vitamin B12 and folate deficiency in some cases.
• Weight loss and low protein during flares.
• Dehydration and electrolyte loss with diarrhoea.
• Blood tests and supplements guided by your doctor or dietitian help.
• Do not start large doses of supplements without advice.

06Diary

Using a food and symptom diary

• Record what you eat and drink, symptoms, bowel movements, stress and medication for 2–4 weeks.
• Look for patterns with specific foods, timing and portion size.
• Remove one suspected food at a time and reintroduce it later to confirm.
• Do not eliminate many foods at once.
• Share the diary with your dietitian or gastroenterologist.
• Remember that triggers can change over time.

07Others

Special diets and what the evidence says

• Low-residue (low-fibre) diet: short-term for flares or strictures.
• Low-FODMAP diet: may reduce IBS-like symptoms in quiescent IBD but does not treat inflammation.
• Specific carbohydrate diet (SCD) and Crohn’s disease exclusion diet: some evidence, mostly for Crohn’s; restrictive.
• Anti-inflammatory and Mediterranean diets: support overall health; evidence for UC is encouraging.
• Gluten-free and dairy-free diets: only helpful if you have coeliac disease or lactose intolerance.
• Probiotics: some strains may help maintain remission in UC (such as VSL#3-type mixtures); discuss with your specialist.
• Always keep taking your prescribed treatment.

09Cases

Three common situations

Someone in a flare with cramps after salad and nuts: switch to low-fibre, well-cooked foods, and keep a diary.

A person in remission avoiding many foods out of fear: reintroduce gradually with a dietitian.

A person with UC and iron deficiency anaemia: blood tests and iron treatment, with dietary support.

10Summary

Key points to remember

During a UC flare, avoid raw, high-fibre, fatty, spicy and very sugary foods, caffeine and alcohol, and choose gentle, cooked, low-fibre options. In remission, widen your diet with a dietitian’s help. Triggers are personal, so keep a diary. Our nutrition team can build a plan around your treatment.

This guide is for general information and does not replace an assessment by your own doctor or dietitian.