IBD Surgery and Diet

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.

• Removal of the ileum

If you have Crohn’s and have had all or most of your ileum removed, you may not be absorbing all the nutrients, such as vitamin B12, which your body needs. Vitamin B12 deficiency can be harmful, and may result in anaemia. Your doctor should be checking whether you are deficient, 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 them, they may spill over into your colon and cause watery diarrhoea. Your doctor can prescribe medication for this. For more information, see our information sheet Managing Diarrhoea.

• Short bowel syndrome
Anyone with less than 200cm of small intestine as a consequence of surgery is said to have a short bowel. On average, the length of a normal adult small intestine is approximately 600cm. 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.

Some people with a short bowel are at an increased risk of kidney stones and may need to go on a low oxalate diet. Your doctor or dietitian will be able to advise you about this. A few people will have an extremely short bowel and in these circumstances, long term parenteral nutrition (nutrients passed intravenously into the bloodstream) may be recommended. It may be possible to have this done at home, and people can remain well on this treatment for a long time.


• Ileostomy and internal pouch
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 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 is lost via an ileostomy than in someone with a colon, because the colon absorbs water and minerals. This may mean that you will need extra fluid and salt to avoid dehydration, especially in hot weather. 

With an ileostomy, there is generally no need for a special diet unless advised by a doctor. However, there are certain foods that 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 diarrhoea.
• Eggs and some types of fish as these can cause strong odours.


People with an internal pouch (known as an ileo-anal pouch), may also find it helpful to avoid the foods listed above. It may also be worth bearing in mind the following: 

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

The stoma nurse or a dietitian can provide dietary advice if you have a pouch or an ileostomy.