A small group of patients requiring nutritional support experience severe malabsorption and maldigestion of nutrients (particularly protein and fat), resulting in them having an inadequate energy and nutrient supply. This may be due to inadequate functioning of the gastro-intestinal tract due to inflammation, reduced concentration of digestive enzymes and/or reduced surface area for nutrient absorption associated with some diseases and treatments. These may include patients with pancreatic enzyme deficiency (pancreatitis, pancreatic cancer, cystic fibrosis), inflammatory bowel disease, radiation enteritis and chemotherapy, short bowel syndrome, HIV-related gastrointestinal disorders, enteric fistulae or intolerance/allergy of unknown cause. Some of these patients will not be able to tolerate a standard feed containing whole protein and fat. In these cases oral nutritional supplements and enteral tube feeds known as 'extensively hydrolysed', 'semi-elemental' or 'peptide-based' with extensively digested protein (containing peptides and small proteins) and containing more easily absorbed types of fat (medium chain triglycerides (MCTs)), can help improve digestion and absorption.