Updated 10 August 2017

The real reason for IBS

New research shows that serotonin, a neurotransmitter generally believed to be involved in mood, is also at the root of irritable bowel syndrome (spastic colon). DietDoc comments.

Irritable bowel syndrome, or IBS (also called spastic colon), is becoming increasingly common. In fact, many of the DietDoc forum users ask for help in this regard.

Until recently, my standard reply on the question "What causes IBS?" has always been, "Researchers don't know yet." But, according to Dr Mauricio Iturralde, a leading gastroenterologist, scientists have at last found out what's at the root of this condition.

Dr Iturralde recently spoke at a talk arranged by Novartis, a pharmaceutical company that produces one of the medications that can be used to alleviate the symptoms of IBS.

Background information
IBS ('prikkelbare derm' in Afrikaans) is a group of symptoms also called a 'syndrome', which includes chronic or recurring pain or bloating or discomfort associated with changes in bowel habits (diarrhoea or serious constipation).

Up to 20% of western populations tend to develop IBS and it occurs in both men and women, but tends to be more common in women. The ratio of IBS in women to men is 3 to 1.

Three types of IBS are recognised:

  • IBS mainly characterised by constipation (C-IBS)
  • IBS mainly characterised by diarrhoea (D-IBS)
  • IBS characterised by alternating constipation and diarrhoea (A-IBS)

Dr Iturralde outlined the following symptoms which are associated with IBS:

  • Visible abdominal distension or bloating (readers often complain that their abdomen expands to such an extent that they 'look pregnant').
  • Relief of symptoms when a bowel movement has occurred.
  • An increased frequency of bowel movements (some patients complain that they have to spend half the day in the toilet), but in general more than 3 bowel movements per day. Conversely, patients with C-IBS may only have 1 or 2 bowel movements per week and suffer from chronic constipation.
  • Passing of mucous with bowel movements.
  • Feelings of incomplete evacuation after a bowel movement.
  • Feelings of urgency to have a bowel movement.
  • Pain varying from mild to severe.

Serotonin and IBS
Patients are often unsure whether IBS can be considered a real medical condition. The answer to this question is "Yes!" IBS is a real medical condition. And thanks to recent research, we now know what causes it.

Scientists have long known that the digestive system is a powerful organ that is capable of producing hormones and neurotransmitters (chemical messenger compounds). Now they have discovered that the gut produces the neurotransmitter called serotonin.

You may have heard that serotonin is a neurotransmitter that influences brain activity and plays a role in appetite control and cravings. This new research has discovered that the same neurotransmitter is also produced in the digestive tract in much larger quantities than in the brain. In fact, 95% of the serotonin in the human body is found in the gut and here it exerts a vital influence on how the digestive tract functions.

Serotonin in the digestive tract is responsible for gut motility (the movement of the gastrointestinal tract) and sensations. Serotonin is involved in feelings of nausea, vomiting, and pain, and gut secretions, and movement. In IBS, the amount of serotonin produced by the gut is either too high (D-IBS) and causes diarrhoea, or too low (C-IBS) and causes constipation.

Because there are so-called 'serotonin receptors' in the gut, which react to the amount of serotonin that is produced and cause the above-mentioned symptoms, researchers have been seeking gut serotonin receptor medications that are able to influence how much serotonin the gut produces and thus alleviate the symptoms of IBS.

The serotonin receptor medications do not influence the amount of serotonin produced in the brain or the effects of brain serotonin.

IBS triggers
Over- or underproduction of serotonin in the gut can be triggered by stress and stressful life events (death of a loved one, divorce, retrenchment, exams etc.). The following factors can worsen the condition:

  • Infections of the digestive tract (gastroenteritis). Up to 32% of patients with IBS develop their condition after having an attack of gastroenteritis.
  • Use of antibiotics
  • Abdominal surgery
  • Dietary factors
    Common trigger foods:
    • Lactose found in milk products
    • Sugar substitutes like sorbitol or mannitol (used in chewing gum and diabetic products)
    • Saturated fat (fat derived from animals or as found in cakes, pies, pastries etc.)
    • Coffee
      • Alcohol
        • Gas-producing foods (legumes or dry beans, peas, lentils, soya and raw onions, cabbage etc.)

      Solutions to IBS
      According to Dr Iturralde, only 25% of patients who suffer from IBS seek medical assistance. Most patients either put up with their symptoms or use home remedies or non-scientific advice to treat their symptoms.

      If you suffer from IBS, then the first step is to have a medical examination by a gastroenterologist (ask your GP to refer you to this type of medical specialist). The gastroenterologist will do certain tests to exclude other conditions that could be responsible for your symptoms, such as coeliac disease (gluten allergy), lactose intolerance and infections.

      The gastroenterologist will then prescribe the necessary medication to help your digestive tract function normally again. He or she will also refer you to a dietician to assist you with the correct diet to ensure that you cut out foods that trigger IBS and include sufficient fibre in your diet (so that C-IBS patients can become more regular).

      If you are highly stressed and need assistance in dealing with controlling this stress, the doctor will also refer you to a clinical psychologist.

      The discovery that IBS is caused by an over- or underproduction of serotonin in the gut is a great breakthrough and all patients who suffer from this painful and disruptive condition can now get the correct help.

      (Dr I.V. van Heerden, DietDoc, updated October 2009)

      (Living with IBS. 2007. Brochure published by Novartis.)

      Read more:
      Bowel blues: myths dispelled
      Anxiety tied to bowel blues


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