Diet after treatment

After your cancer treatment you may find you can’t eat the same foods as you did before. These changes may be temporary or longer-lasting. This page has information about eating a balanced diet, eating when you have a stoma and how diet can help with problems like weight change, diarrhoea and constipation.

Always speak to your healthcare team or a dietitian before making any big changes to your diet

A balanced diet

It’s important to follow a healthy, balanced diet to help you feel physically and emotionally well.

Your balanced diet will be individual to you. It'll depend on your age, weight, gender and how active you are.

The NHS website has an Eatwell Guide, which shows how much of each food type to include in your diet. The foods you can eat may vary during and after your cancer treatment and you may find you can’t eat the same foods as you did before your bowel cancer diagnosis.

Tips for following a balanced diet

• Eat at least five portions of vegetables and fruit each day
• Eat more wholegrain variety carbohydrates, such as bread, pasta and rice, unless your healthcare team has advised you to follow a low-fibre diet
• Eat some lean protein, such as skinless chicken, fish or pulses each day
• Include some lower-fat dairy or non-dairy alternatives in your diet
• Cut down on saturated fats and sugar
• Drink six to eight glasses of fluid each day – water is best but if you struggle to drink enough, you could try drinking sugar-free squash, tea or coffee instead
• You could also try eating food that contains water, such as soup or melon

Remember: Always speak to your healthcare team or a dietitian before making any big changes to your diet.

You can find more information and tips on following a balanced diet in our booklet Eating Well.

Fibre

Dietary fibre is the part of plants that the body can’t digest easily, so some of it passes into the bowel without being absorbed. A diet rich in fibre is important for bowel health, as it helps move food more quickly through the bowel and supports the growth of good gut bacteria. Fibre also keeps you feeling full for longer, so can help you control your weight and appetite.

How much fibre?

Healthy adults should eat at least 30g of fibre a day. Your healthcare team will explain how much fibre you need to include in your diet, depending on which treatment you’ve had. They can also help if you find that you can’t cope with high-fibre foods.

Low-fibre diets

Your healthcare team may advise you to follow a low-fibre diet, for example before and after treatment. Ask your healthcare team how long you should follow this diet. You may be able to gradually start eating more fibre after a few weeks.

You may be worried about how you can eat enough vegetables and fruit if you're following a low-fibre diet. Your healthcare team will give you advice. You could try foods containing soluble fibre, which is easier to digest, such as:

• fleshy parts of vegetables, such as cucumber, peppers and tomatoes, with the skin and seeds removed
• well-cooked vegetables that are lower in fibre, such as courgettes, squash, carrots, parsnips, swede and sweet potatoes
• lower-fibre fruits such as bananas, melon, seedless grapes, and peeled fruits such as apples, pears and peaches
• tinned fruit in juice (rather than syrup) with no skin, pith or seeds
• frozen berries that have been defrosted and sieved
• fruit juices – only have one serving each day, as fruit juice is high in sugar

Adding fibre to your diet

Increase fibre gradually to avoid wind, bloating and stomach cramps. For example, you could add an extra portion of vegetables to your diet every few days. Fibre attracts water so it’s important to drink plenty of fluids like water, low-fat milk or herbal teas to help prevent constipation. Avoid sugary or fizzy drinks as these can lead to weight gain.

After treatment, you may find it hard to digest high-fibre foods such as bran, nuts or seeds. Over time, you can try to gradually increase the amount of fibre you eat. To start with, you can make fibre easier to digest by cooking vegetables and fruit well and removing their skins.

Should I take supplements?

You should be able to get all the vitamins and minerals you need from a healthy, balanced diet. You may need some extra help if, for example, there are some foods you can’t eat, you follow a vegan or other restricted diet, or you have a poor appetite. Many vegan foods have nutrients added so it’s worth checking the label.

Don’t take high doses of supplements as they can be harmful. It’s especially important not to take any vitamins or food supplements during your cancer treatment unless they’ve been recommended by your doctor, dietitian or other qualified healthcare professional.

Eating with a colostomy

Many people with a colostomy can eat a healthy, balanced diet. If you had constipation or diarrhoea before having a colostomy, you may find that you continue to have these symptoms.

You may find that some types of food give you bowel symptoms such as wind or loose poo. Cutting back on these types of food can help.

To help prevent constipation, drink six to eight glasses of fluids a day. Water is best but you can also have tea, coffee or sugar-free squash. Limit fruit juice to one glass a day.

Make sure you’re eating enough fibre and have at least five portions of vegetables and fruit each day. For the first few days after surgery, make sure vegetables are well cooked. You may cope better with fruit that’s cooked, rather than raw.

Daily gentle physical activity such as walking is also important.

If you have constipation, make sure you’re eating regular meals to keep your stoma working. Food that is spicy or high in fibre can help to relieve constipation. If you want to eat more fibre, introduce it to your diet gradually and make sure you’re drinking enough fluids. Contact your stoma care specialist nurse or call 111 if there are any signs that your colostomy isn’t working properly, such as:

• watery poo or not passing many poos
• stomach cramps and bloating
• feeling or being sick (nausea or vomiting)
• a swollen stoma

If you have diarrhoea, speak to your stoma care specialist nurse. They may give you medicine to slow the movement of food through your bowel and thicken the output. Foods that may thicken your poo include very ripe bananas, boiled rice, porridge, smooth peanut butter, white bread or pasta.

Eating with an ileostomy

When you first have an ileostomy, you may find that some types of food are harder to digest.

Your healthcare team may advise you to follow a low-fibre diet to start with.

Avoid fruit straight after surgery, except for bananas which thicken the output from your ileostomy. Gradually introduce cooked fruit, like stewed apple. After six to eight weeks, you should be able to start eating more types of food.

You can eat vegetables and fruit as part of a healthy, balanced diet, but chew them well to reduce the risk of blockages. If you have problems eating these foods, you could try taking off the skin and removing the seeds or eating tinned vegetables and fruit in natural juice or water.

Eating lots of small, hard foods like raisins, nuts and sweetcorn can sometimes block the ileostomy. You can help prevent this by eating small amounts of these foods and chewing them well. You could try crushing nuts or creaming sweetcorn.

You may sometimes get an increased output of poo from your ileostomy. This may be caused by stomach infections, stress, antibiotics, spicy food, beer or lager. Here are some things you can do to help:

• Keep drinking water to stay hydrated – aim for six to eight glasses a day
• If you’re able to, eat salty foods or add a little salt to your meals to replace the salts lost in loose poo. If you have high blood pressure, heart or kidney problems, check with your stoma care specialist nurse first
• Cut back on foods that increase the amount of poo you pass, such as fruit, vegetables, fried foods, fruit juice, caffeine and alcohol
• Thicken the output by eating bread, rice, potatoes, pasta, oats, smooth nut butter, bananas and crackers

Tell your stoma care specialist nurse if you have increased output over a long period of time, feel thirsty or faint, or have dark yellow urine. These can be signs of a high-output stoma, which can cause dehydration. If your ileostomy stops working, you may have a blockage. This can cause pain in your stomach area (abdomen) and you may feel sick. Contact your stoma care specialist nurse for advice. They may suggest that you:

• keep drinking fluids
• stop eating solid food
• don’t use laxatives
• make the opening of your stoma appliance slightly larger if your stoma swells
• massage your stomach area (abdomen) and around the stoma
• try a warm bath to ease pain in your stomach area
• go to the hospital emergency department if you haven’t passed any poo or wind from your ileostomy for more than six hours

Get medical help from your hospital emergency department straight away if your stomach area is very painful and bloated and you start being sick (vomiting). Your bowel may be blocked, and you may need treatment quickly.

Eating with a low appetite

Bowel cancer and its treatment can affect how much you’re able to eat and drink.

Speak to your GP, specialist nurse or dietitian if you're having problems with eating enough. They can give you emotional support and practical help to eat a balanced diet. They may prescribe medicines, for example if you have sickness or a sore mouth.

If you're a family member or carer and you’re worried about someone who has lost their appetite, you can speak to a healthcare professional on their behalf.

Tips for boosting appetite

• Try to make mealtimes enjoyable, for example by eating in a relaxed environment or with friends and having the foods you enjoy
• Eat at similar times each day. Your appetite will start to adjust to these planned mealtimes, which can help you look forward to meals
• Fresh air and physical activity before meals can help you feel hungry. Even a short, gentle walk can make a difference
• If food smells make you feel sick, try to stay away from the kitchen and ask friends or family to cook. Eating foods that don’t need cooking may also help, such as cheese and crackers or breadsticks with dip
• Use herbs, spices, pickles and sauces, flavoured olive oils, lemon and lime juice to add flavour to food
• Pre-prepared foods that can be chilled or frozen can be useful if you don’t have time to cook or if you aren’t able to cook for yourself. Make sure they’re reheated properly before eating
• Make large meals that you can eat in smaller portions, such as soup, dhal or lasagne. This allows you to go back for more if you want to
• If you find that you get full quickly, don’t drink anything for half an hour before a meal. Only have small sips during your meal, unless you need fluids to help you swallow. Drink more between meals
• If you don’t feel like eating, you could try energy-rich drinks, like smoothies

You may also find these tips helpful if you’re struggling to gain weight.

Gaining weight safely 

What causes weight loss?

Bowel cancer may cause weight loss in some people. There may be several possible reasons for your weight loss, such as the cancer itself or the side effects of treatment.

If you’re eating normally but still losing weight, the cancer may be affecting how your body absorbs and uses the nutrients in your food.

Side effects of treatment such as constipation and diarrhoea can affect your appetite. Extreme tiredness (fatigue), a change in your senses of taste and smell, feeling and being sick, and emotional stress can lead to problems with eating. Getting medical advice and treatment for these symptoms may help you to eat more and put on weight.

Speak to your GP or healthcare team if you’ve lost a lot of weight or if you’re losing weight quickly. It’s important to find out what’s causing your weight loss and you may need treatment.

If you’re finding it hard to put on weight, ask your GP or healthcare team to refer you to a dietitian.

How can I put on weight?

To gain weight safely, you need to eat more calories and keep active. Eating several small meals each day can help you eat more calories and digest your food more easily. Try to include energy-rich foods such as peanut butter or Greek yoghurt to your meals and snacks. Make sure you have the food and drinks that you enjoy.

You could also try high-calorie or ‘build-up’ drinks with added vitamins and minerals. You can buy these over the counter from pharmacies or your dietitian may give you a prescription for them.

If you feel well enough, try to do some regular gentle physical activity. This can help build up your muscle strength and may help improve your wellbeing. Ask your GP or healthcare team to be referred to a physiotherapist, who can help you find activities that are safe to do during and after cancer treatment.

Losing weight safely

If you’re overweight, it’s important to speak to your healthcare team before trying to lose weight. They can give you information on which types of food you should eat, depending on the treatment you’ve had and any side effects you’re having.

Following a healthy, balanced diet and doing regular physical activity can help you lose weight. If possible, aim for at least 30 minutes, five days a week. Build up your physical activity gradually. You can try going for gentle walks and avoid sitting for long periods of time.

Ask for help from your GP or healthcare team if you need support.

Tips to lose weight safely:

• Start the day with a healthy breakfast, such as porridge, wholegrain cereals or bread, boiled or poached eggs, lower-fat milk and a portion of fruit
• Choose lower-fat options where available but remember that many low or non-fat foods contain more sugar
• Replace refined starchy foods such as white bread, white rice and white pasta with wholegrain varieties
• Think about your portion sizes. Even healthy food, such as olive oil and nuts, can make you put on weight if you eat too much
• Try to avoid sugary snacks and choose healthier options, such as a small portion of nuts and seeds or some carrot sticks with cottage cheese or low-fat hummus
• Swap creamy, fatty or sugary food and drinks for fruit, vegetables and water
• Keep active and eat healthily most days, including weekends and holidays
• When you’re exercising, drink water instead of sugary drinks,sports drinks or fruit juice
• Remember that alcohol contains calories. Drink as little as possible and no more than 14 units a week. A glass of wine or a pint of low-strength lager is 2 units

Some people find it helpful to keep a record of their progress. You could weigh yourself once a week or note down how much you eat and drink, and how much physical activity you do. You could also ask friends or family to support you. Being active and eating healthily together can help you both keep on track.

Can diet help to prevent bowel cancer coming back?

We don’t yet know how to stop bowel cancer coming back after treatment. There’s some suggestion that the following things may help reduce your risk of cancer coming back, but we need more research and evidence to fully understand this.

Making healthy lifestyle choices is good for your overall health and can prevent or reduce other health problems, such as diabetes and heart disease.

Here are some tips for leading a healthy lifestyle:

• Stay a healthy weight. Measuring your body mass index (BMI) is one way of finding out if you’re a healthy weight for your height. Visit the NHS website for information on BMI
• If you’re able to, be physically active for at least 30 minutes a day and spend less time sitting down
• Avoid high-calorie food and sugary drinks
• Eat more wholegrains, vegetables, fruit and beans
• Limit red meat and avoid processed meat
• Avoid alcohol if possible. If you do drink alcohol, drink no more than 14 units a week and spread it out over the week, with at least two alcohol-free days a week

More support

Speak to your GP or healthcare team if you have any worries about your diet or your ability to keep physically active. They may refer you to another health professional, such as a dietitian or physiotherapist.

More information

Find out more about eating and drinking with diarrhoea and constipation after treatment.

There’s more information on diet after bowel cancer in our booklet, Eating Well.

Updated February 2024