Last updated:29th September 2017

AS and the gut

Understanding the gut

The gut is the long tube that starts at the mouth and ends at the back passage (anus).

Food passes down the oesophagus into the stomach and then into the small intestine. The small intestine is where food is digested and absorbed into the bloodstream.

The gut then changes to become the colon and rectum. The colon absorbs water and contains food that has not been digested, such as fibre. This is passed into the last part of the large intestine where it is stored as stools (faeces).

Around one in twelve people with AS also have inflammatory bowel disease

There are two types of inflammatory bowel disease: Crohn's disease and ulcerative colitis.

Crohn's disease

Crohn's disease is a long term condition that causes inflammation of the digestive system. Inflammation is the body's reaction to injury or irritation, and can cause redness, swelling and pain.

Crohn's Disease is named after Dr Crohn, who reported a number of cases in the 1930's.

The inflammation can affect any part of the digestive system, from the mouth to the back passage, but most commonly occurs in the last section of the small intestine (ileum) or the large intestine (colon).

Symptoms vary depending on which part of the digestive system is inflamed but common symptoms include:

  • recurring diarrhoea
  • abdominal pain and cramping, which is usually worse after eating
  • extreme tiredness (fatigue)
  • unintended weight loss
  • blood and mucus in your faeces (stools)

There may be long periods that last for weeks or months where you have very mild or no symptoms (known as remission), followed by periods where the symptoms are particularly troublesome (known as flare-ups or relapses).

There is currently no cure for Crohn's disease. However, medication is available that can be used to treat the symptoms and prevent them from returning.

 Crohn's and Colitis UK have produced a very good guide to Crohn`s Disease.

Ulcerative colitis

Ulcerative colitis is a long term condition affecting the colon.

Ulcerative colitis causes the colon to become inflamed. In more severe cases, painful sores (ulcers) may form on the lining of the colon. These ulcers can bleed and produce mucus and pus.

Symptoms of ulcerative colitis include:

  • diarrhoea which may be mixed with mucus, pus or blood
  • abdominal pain
  • pain when passing stools
  • a frequent need to go to the toilet
  • weight loss

Symptoms of ulcerative colitis can range from mild to severe. The condition is very unpredictable. Symptoms can flare up and then disappear for months or even years.

 Crohn's and Colitis UK have produced a very good guide to ulcerative colitis.





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