Irritable bowel syndrome (IBS) is a chronic condition of the digestive system. This condition causes abdominal pain and altered bowel habits1. The main complaints are either frequent, watery bowel movements (diarrhoea) or not frequent enough bowel movements (constipation). In some patients these symptoms may switch between diarrhoea and constipation1. IBS is the most commonly diagnosed gastrointestinal condition 2 and is second only to the common cold as a cause of absence from work 3. An estimated 10–20% 1 of people in the general population experience symptoms of IBS, although only about 15% of affected people actually seek medical help 4. Although the condition cannot be cured, treatments are available to alleviate symptoms.