Nutritional support, including oral nutritional supplements, enteral tube feeding and parenteral nutrition, can be an important part of the management of any patient. Malnutrition is common and costly, clinically and financially, if left untreated. In patients with, or at risk of, malnutrition, the appropriate use of nutritional support can prevent complications arising, produce other clinical, functional and financial benefits, and can be life saving in some situations. This article discusses the evidence from systematic reviews and meta-analyses of the effectiveness of nutritional support.