At Ersta hospital we have for many years done research studies on the metabolic response in connection with surgery. Patients undergoing surgery for cancer in the rectum often are prepared with energy drinks in order to receive a higher energy level before the operation. As a result of this the patients often avoid nausea and have a better intestinal function after surgery. We think that this treatment has worked well on the patients but no scientific studies have been done on these patients. As a complementary result of the treatment with nutritional drinks we have found that the colon is empty already after a short time of treatment. We have also prepared some patient for colonoscopy, that due to their primary disease not are able to use traditional purgatives, with nutritional drinks for five days combined with a local purgative on the day of the examination. The colonoscopy examination on these patients were performed without any problems. We have found no studies describing this preparation before colonoscopy.