Some carbohydrates, particularly fructose, the sugar found in fruit and bread may cause bloating, pain and erratic bowel habits (diarrhoea and constipation) particularly in patients suffering from the irritable bowel syndrome (IBS). This may be because they are not well absorbed in the small intestine and cause water to be trapped in the bowel causing distension. Studies have shown that reducing the amount of these sugars in the diet can relieve these symptoms. There is some evidence that combining fructose and glucose can reduce the symptoms caused by fructose but just why is unclear. In this study, the investigators will use a non invasive medical imaging technique called "magnetic resonance imaging" (or MRI) to look at the behaviour of drinks containing these sugars in the bowels of healthy human volunteers.