By the time we’re aged 45, about a third of us will have developed small bulges or pockets in our lower bowel or colon.

These are called diverticula.

By the time we’re 70, two out of three of us (66 per cent) will have these pockets, which are said to occur in weak spots along the bowel.

When you develop these pockets, you’re said to have a condition called diverticulosis, which tends to be asymptomatic.

How has this happened?

It may be that constipation, and attendant straining, has put pressure on the weak spots.

Given that ageing clearly is a factor, it may be that these weak spots develop over time, through wear and tear.

But there can be other reasons why these pockets develop.

Some people have a genetic predisposition. Research suggests these pouches might occur in people with immune problems … which in turn suggests chronic inflammation.

Certain medicines that cause constipation (such as opioids) might cause the pockets to develop.

Otherwise, a low-fibre diet, eating too much red meat, lack of physical activity, obesity, dehydration or connective tissue problems in the colon could all play a part.

There is no single cause set in stone.

Diverticular disease

The more of these pouches you develop, the greater the risk of your bowel acting up.

When you develop symptoms because of these pouches, you have a condition called diverticular disease.

Even then, it’s largely a mild condition. Your symptoms might suggest you’re just a bit out of whack.

These symptoms could include:

• Mild abdominal pain and bloating
• Constipation and diarrhea
• Flatulence
• Bleeding. Your complacency can be jolted by blood in your faeces. This is usually minor, but can be heavy when there’s inflammation. Any bleeding should be quickly investigated by your doctor
• Anaemia can occur when the bleeding is persistent.

Once blood enters the picture, you might convince yourself that you’ve got cancer, which is rarer.

Ask your doctor to investigate.

For most cases, treatment involves short-term use of laxatives to ease the constipation, and a gradual shift to a diet higher in soluble fibre. For more information about treatments, see here.

Diverticulitis

While diverticular disease (having pouches with mild symptoms) is common, diverticulitis – when one or more of the pockets is inflamed or injured – is an uncommon complication.

In the rarest of cases it can tip into a medical emergency.

It affects about 4 per cent of people with diverticulosis. Once you’ve had it, there’s a 20 per cent chance of getting it again.

Symptoms of diverticulitis include:

• Sharp pain, often located at a specific point, In people of European descent, diverticulitis pain is felt in the lower left quadrant of their abdomen. In people of Asian descent, this pain is more common in the upper abdomen
• Fever
• Distension (bloating) of the abdomen
• Nausea and vomiting.

Most cases can be treated with fasting, rest and antibiotics, and painkillers such as paracetamol (not aspirin, which can cause bleeding, and not opiates because they cause constipation).

The complications can be dire

Complications of diverticulitis can be dire – and often require surgery, with unhealthy sections of the bowel being removed – but are mercifully very rare.

Possible complications include:

• Abscess – a ball of pus
• Bowel obstruction
• Fistula. This is an abnormal pathway created between two organs. Sometimes, after a severe diverticulitis flare up, a fistula forms between the large intestine and nearby organs. Surgery required
• Perforation – a weakened pocket of bowel wall may rupture. This is a medical emergency
• Peritonitis – a potentially life-threatening complication where perforation has caused an infection of the membranes that line the abdominal cavity and abdominal organs
• Haemorrhage.

At its worst, it may not be immediately possible rejoin the healthy sections of bowel.

In this case, a colostomy bag needs to be fitted. The bag is usually temporary. The bowel is repaired and rejoined after six to 12 months.

Last word: Get more fibre in your diet, drink more water and do some exercise. These may stop you developing those damn pouches in the first place.

See here for more information.