A number of nutritionally related changes in bowel function may cause acute intestinal problems during radiotherapy. These include: Bile-acid & pancreatic enzyme potentiated damage to mucosa causing loss of epithelial integrity and in turn increased permeability to antigens and luminal bacteria; Bile-acid malabsorption, decreasing the gut's ability to digest fat; Reduced disaccharidase activity due to loss of the intestinal brush border, causing malabsorption of sugars leading to osmotic diarrhoea; Statis/ dysmotility in the small intestine prompting bacterial overgrowth.