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The science of nutrition and healthy eating
The science of nutrition and healthy eating

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4 Irritable bowel syndrome (IBS)

The cause of IBS is unknown but it may develop after a gut infection, a course of antibiotics or a traumatic or an upsetting event. Symptoms often increase because of stress and anxiety. IBS is a collection of unexplained symptoms where there is a disturbance in the bowels. This includes abdominal pain, bloating, constipation and diarrhoea. Many of these symptoms are similar to food intolerance because there is sensitivity to certain foods.

An image of someone holding their stomach, with red colouring centred on their stomach.
Figure 7 Irritable bowel syndrome

The IBS Network website states: ‘At any one time, IBS affects around 10–20% of people living in the UK.’

Women tend to have IBS more than men (in a ratio of 3 to 2) and it tends to start in their teenage or twenties. The symptoms of IBS can be lifelong and alter in intensity according to several factors related to food and stress. IBS does tend to occur in families but there is not necessarily a genetic factor because the environment is a strong contributing factor. The food eaten by the family tends to be the same and hence affects their colonic bacteria.

With IBS, the gut immune system is stimulated, inducing mild inflammation, and colonic bacteria are depleted. This all leads to a sensitive gut.

If a person suspects they have IBS, it cannot be diagnosed. But there is a process of elimination of other conditions such as coeliac disease or inflammatory bowel disease.