Eating after surgery

Surgery should not make a major difference to what you eat - but there are some points to bear in mind, depending on the type of surgery involved.


The ileum is the last part of the small intestine, before it joins the colon. Some people with Crohn’s may have all or part of their ileum removed. The last part of the ileum is responsible for absorbing vitamin B12 - so you may not be absorbing enough. Vitamin B12 deficiency can be harmful, and may result in anaemia. Your doctor can check this with a simple blood test, and may suggest that you receive a vitamin B12 supplement by injection. The ileum also absorbs bile salts. These salts (which come from your liver) are used to transport and absorb fat. If you do not have enough ileum left to absorb the bile salts, they may spill over into your colon and cause watery diarrhoea. Your doctor may prescribe medication for this. For more details, see our information sheet Diarrhoea and Constipation.


The length of a normal adult small intestine is approximately 600 cm. Anyone with less than 200 cm of small intestine as a consequence of surgery is said to have a short bowel. This means that there is a reduced area available to absorb nutrients and you may have to go on a specialist diet in order to maintain a healthy weight. A few people have an extremely short bowel and in these circumstances, long-term parenteral nutrition (nutrients passed directly into the blood stream through an intravenous drip) may be recommended. For more information, see the section on Nutritional treatment.


Having an ileostomy (where the colon has been removed and the small intestine ends in an artificial opening through the abdominal wall) should not mean you have to make drastic changes to your diet. This may seem unlikely in the weeks following your operation, but things should settle down over time. You may find that it takes you a little while to get used to your ileostomy, and that it helps to add foods to your diet one at a time in order to judge their effect on your digestive system. More salt and water will be lost through an ileostomy than in someone with a functioning colon, because the colon absorbs water and minerals. This means that you may need extra fluid and salt to avoid dehydration, especially in hot weather. On the other hand, if you have a high-output ileostomy you may actually need to restrict your fluid intake to avoid dehydration. Your IBD team will tell you if you have a high-output ileostomy, and can also help you manage your general diet and fluid intake.

Although there is generally no need to follow a special diet unless you are advised to by your doctor, there are certain foods which you may find helpful to avoid. For example:

  • Nuts, fruit skins and some vegetables which may cause blockages
  • Fizzy drinks and ‘windy’ vegetables such as cabbages and beans which may cause gas
  • Beer, chocolate and some fruit which may cause diarrhea
  • Eggs and some types of fish as these can cause strong odors

Your stoma nurse or IBD dietitian should be able to help you with dietary advice.


People with UC may have surgery to form an internal pouch (also known as an ileal-anal pouch) if they have had their colon removed. In general, you should be able to eat a normal diet, but it may be worth bearing in mind the following:

  •  Anal irritation can be caused by coconut, spicy foods, some fruit and food with pips. They may also cause colicky pain (abdominal cramps), which is usually only temporary
  • Alcohol may also cause dehydration (if taken in excess) and you may find that beer and red wine increase pouch output