Diverticular disease (pūtautau i te whēkau) is the name given to this long-term condition which causes small pockets or out-pouchings to occur in your bowel (diverticulosis).
These pouches or pockets (diverticula) can remain trouble-free or they can become inflamed, causing pain and constipation. They become inflamed when undigested food becomes trapped within them, at which point we call it diverticulitis.
Having diverticula is very common, occurring in about half of all people over 60 years of age. Most people do not get any symptoms. Doctors believe the main cause is a low-fibre diet. Diverticula are caused by a weakness in the wall of the bowel. This weakness is thought to be caused by genetic factors or a diet which is low in fibre. 
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Symptoms
Diverticulosis
Most people with diverticulosis don't have symptoms. Sometimes it causes mild cramps, bloating or constipation. Diverticulosis is often found through tests ordered for something else. For example, it is often found during a colonoscopy to screen for cancer. A high-fibre diet and mild pain reliever will often relieve symptoms.
If the pouches become inflamed or infected, you have a condition called diverticulitis.
Diverticulitis
The most common symptom of diverticulitis is abdominal pain, usually on the left side. You may also have fever, nausea, vomiting, chills, cramping, and constipation. In serious cases, diverticulitis can lead to bleeding, tears, or blockages.
If you have pain, fever and chills, this can be serious and you should seek medical treatment immediately.
Diagnosis
To diagnose diverticular disease it is necessary to examine the inside of your bowel. This is usually done in two ways. Insertion of a tube up your back passage, through which the doctor can see inside your bowel and examine the bowel wall (colonoscopy).
A barium enema can also be performed. Barium is fed into the bowel through the back passage and a series of x-rays are taken which show the outline of the inside of the bowel wall.
Treatment
Diverticulosis
People with bowel pouches, which have not become inflamed, generally only require a change in diet to improve their condition. The diet must include good quantities of roughage. At least five servings of fruit and vegetables a day should be eaten (a serving is roughly the size of your cupped hand). Fibrous fruits such as apples and pears are best, along with fresh fruits, vegetables and whole grain cereals.
Increasing the fibre in your diet may cause wind and abdominal pain for a few weeks. This is caused by the bowel adjusting to the change in eating habits. Increase the fibre gradually to minimise this problem.
It can be helpful to visit a dietitian after being diagnosed with diverticular disease to go through what foods are best for you.
Diverticulitis
When the bowel pouches have become inflamed (diverticulitis), treatment is aimed at resting the bowel, relieving pain and fighting infection. At this stage, a low-fibre, or fluid only diet, is recommended to rest the bowel.
- On a low-fibre diet, it is important to prevent constipation and laxatives are prescribed to do this.
- Bowel spasms can be painful when the pouches are inflamed – painkillers or anti-spasmodic tablets are prescribed to help.
- In many cases, uncomplicated diverticulitis is caused by inflammation rather than infection. Therefore antibiotics are not usually needed. They may be considered if your symptoms continue or get worse despite changes to your diet and taking painkillers.
Occasionally, surgery needs to be performed to remove affected parts of the bowel.
Probiotics
Although more research is needed, research suggests probiotics may help treat the symptoms of diverticulosis, prevent the onset of diverticulitis, and reduce the chance of recurrent symptoms. Probiotics are live bacteria, like those normally found in the GI tract. Probiotics can be found in dietary supplements – in capsules, tablets, and powders – and in some foods, such as yoghurt.
Learn more
Diverticular disease National Institute of Diabetes and Digestive and Kidney Diseases, US, 2013
Diverticular disease and diverticulitis NHS Choices, UK
Diverticulosis, diverticular disease, diverticulitis Patient Info, UK, 2020
Reference
Antibiotics – choices for common infections BPAC, NZ, 2017