Diet and late bowel effects

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Many bowel late effects can be managed with some adjustments to what you eat.

Changes to your diet can help to manage diarrhoea, constipation and wind. Your doctor may refer you to a dietitian for expert advice on managing your diet.

Fibre is important in regulating the way the bowel works. Insoluble fibre helps manage constipation, soluble fibre helps bulk up and slow down bowel movements. Foods such as wholegrain bread and cereals are full of insoluble fibres. Soluble fibre is found in foods like bananas, oats and beans.

Sometimes radiotherapy to the pelvis can make you intolerant to certain foods. You may become lactose, fructose or gluten intolerant, which means you may feel bloated or have more wind after eating dairy, fruit or foods with wheat in them.

Knowing how different foods affect your body can make it easier to change your diet to improve the late effects you have.


What you eat affects your bowel. For example, fatty or spicy foods, or too much or too little fibre, can stimulate the bowel. This makes it harder to control. Caffeine, alcohol and artificial sweeteners can also cause problems.

Your doctor can refer you to a dietitian for expert advice on managing your diet. If you’re losing weight because of bowel problems, it’s especially important to see a dietitian.

Foods affect people differently, so you may need to try a few things before you work out what’s best for you. Try to find out which foods cause constipation or make your bowel motions loose. You may be able to eat less of these foods without cutting them out altogether. See our food guide below for information about foods that can cause or improve bowel problems.


Fibre is important in regulating the way your bowel works.

There are two types of fibre:

  • Insoluble fibre helps with managing constipation, and it can also help with other bowel problems. You can get insoluble fibre from bran and seeds. It’s also in multigrain, wholemeal and wholegrain foods, such as bread and cereals.
  • Soluble fibre helps bulk up and slow down bowel movements, so it may help improve diarrhoea or soft stools. You can get soluble fibre from oats, porridge, bananas, and from apples and pears with their skins removed. It’s important to remove the skins, because they contain insoluble fibre. Pulses, such as baked beans and lentils, are also high in soluble fibre. But pulses stimulate the bowel, so they aren’t recommended for people with diarrhoea or soft stools.

Your specialist nurse, continence adviser or gastroenterologist will advise you on the type of fibre you need and how much you should have.

If you’re adding fibre to your diet, do it slowly. This gives your body time to adjust. Start with small amounts and slowly increase the amount when you’re ready. Make sure you drink more water while you’re having more fibre.

Adding more fibre won’t be right for everyone. After pelvic radiotherapy, you may not be able to cope with as much fibre in your diet as before. So it may not be appropriate to follow the ‘five a day’ plan for fruit and vegetables. Some high-fibre foods make the bowel produce a lot of gas (wind). If wind is a problem for you, you may need to avoid these foods.

Fibre supplements

People who have frequent bowel motions or incontinence can often be prescribed soluble fibre supplements, such as Normacol® or Fybogel (soluble fibre). These supplements are also used to prevent constipation. They work by absorbing water and expanding to fill the bowel. This makes the stools bulkier and easier to push out.

Some people find that Fybogel can make the bowel produce a lot of gas (wind).

You can buy some fibre supplements at the chemist, or your doctor can prescribe them. When you’re taking fibre supplements, always make sure you drink plenty of fluids – at least two litres every day.

Food intolerance

Sometimes radiotherapy can affect how well your bowel copes with certain food types, such as:

  • lactose, which is found in dairy products
  • fructose, which is a fruit sugar sweetener often found in products labelled ‘no added sugar’
  • gluten, which is a wheat-based protein found in breads, cakes, biscuits and pasta.

Symptoms of food intolerance may include tummy cramps, feeling bloated, and having more wind after eating a particular food. If you think you may have a food intolerance, ask your GP to refer you to a gastroenterologist.

I have cut out nearly all caffeine. I eat root veggies, but no green veg. No spicy foods. No fizzy drinks and not much alcohol. It has made a huge difference.


Food guide

Below we list the foods that may cause or help bowel problems. This is only a guide, as foods can affect people in different ways.

Foods that may cause wind

If you have wind, the foods you should avoid include:

  • vegetables such as sprouts, broccoli, cabbage, cauliflower, cucumber, onions, radishes, spinach and sweetcorn
  • baked beans, kidney beans, lentils, chickpeas and other pulses
  • nuts
  • dairy products
  • drinks such as beer and fizzy drinks
  • chewing gum
  • sorbitol (a type of sugar found in some artificial sweeteners, in some sugar-free foods and in apples, pears and peaches).

Foods that may help make your stools firmer

If you have problems with diarrhoea, loose stools or frequent bowel movements, these foods may be helpful.

These foods include:

  • apples and pears with their skins removed
  • bananas and potatoes
  • yoghurt
  • white bread (not a high-fibre variety), white rice (boiled) and pasta (not a wholemeal variety)
  • chicken and fish.

Foods that stimulate the bowel, and make stools softer or more frequent

If you have problems with diarrhoea, loose stools or frequent bowel movements, you should limit these foods. If you have constipation, these foods should help. 

These foods include:

  • some types of fresh, tinned or dried fruit – grapes, fruits with stones (such as apricots, plums, peaches and prunes), and most berries (except blueberries)
  • fruit juices, such as prune, orange, apple and grape juices
  • vegetables such as broccoli, sprouts, cabbage, garlic, onions, peas, peppers, spinach and sweetcorn
  • beans, especially baked beans, kidney beans and chickpeas
  • bran and foods high in insoluble fibre
  • greasy foods and fried foods
  • spices such as chilli, curry and ginger
  • caffeine in coffee, tea, chocolate drinks, cola drinks and energy drinks
  • nuts, linseed and popcorn
  • sugar-free foods containing sorbitol, mannitol or xylitol (such as sugar-free chewing gum, some mints, sweeteners and ‘diet’ drinks and foods)
  • chocolate
  • alcohol – especially beer and red wine
  • some supplements, such as the mineral selenium, which the body only needs in small amounts.

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