Diverticulitis Causes

Diverticulitis is a common digestive condition caused by infection and inflammation of the intestinal lining.

The intestine is made up of a flexible inner layer that is covered by a large muscular outer layer. After food has been broken down and digested in the small intestine, it enters the large intestine where the remaining nutrients and water are absorbed. This leaves undigested waste that is pushed through the rectum and out of the anus in the form of a stool.

As a person ages, the intestinal wall becomes weaker and small bulges or diverticula may form on the outer lining of the intestine due to the pressure exerted by stools as they pass through the colon. A lack of fibre in the diet is thought to be the main cause of this condition, which is more common among older individuals.

Most people do not develop any symptoms but people who do are said to have diverticular disease. In some cases, one or more of the diverticula become infected and inflamed which can cause more serious complications such as abscesses, fistula and obstruction. This infection and inflammation of the diverticula is referred to as diverticulitis.

Diet and diverticulitis

Fibre in the diet helps to soften stool which prevents constipation and allows the stool to be passed easily through the large intestine and rectum. When the diet is rich in fibre, less pressure is required by the walls of the large intestine to squeeze and move the stool towards the rectum.

On the other hand, a diet low in fibre causes small, hard stools to form, which leads to straining of the intestinal wall to push them out. This causes weak spots in the muscular layer of the intestinal wall. The inner layer then pushes through these weak spots, which gives rise to the formation of diverticula.

Age and diverticulitis

As a person ages, the walls of the colon become progressively weaker and the passing of hard stools increases the likelihood of diverticula forming. Almost half of people develop diverticula by the time they are 50 and about 70% of people have them by the age of 80.

Other causes of diverticulitis

Only around a quarter of people who have diverticula go on to develop symptoms of the condition. However, certain risk factors for developing diverticular disease have been developed and these include:

  • Being overweight
  • Smoking
  • A history of constipation
  • Lack of physical activity
  • The use of non-steroidal anti-inflammatory drugs (NSAIDs)

Further Reading

Last Updated: Jun 10, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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