After written consent is obtained, patients will be asked to fast from 12.00am on day one. At 08.00am patients will be asked to pass urine and to empty their stoma bag. After this they will be asked to drink 200ml of the ONS which they have been randomised to test on day one over a 30 minute period. Urine and intestinal output will be collected into two separate containers over the next 6 hours. During this time the patient will not be permitted to eat or drink other fluids. After 6 hours the patient will be able to eat and drink normally. The urine and intestinal output will be weighed and then an aliquot will be stored in a -20oC freezer before being sent for analysis. Day two is a washout day when the patient will be able to eat and drink normally. Day three will be the same as day one but the patient will have the other ONS that they did not have on day one. No changes will be made to the patient's usual anti diarrhoeal and/or anti motility agents or parenteral support during the study.