The major function of the digestive system is the absorption of virtually all energy and nutrients from the diet. Any condition that interferes with this process is referred to as ‘malabsorption’. Carbohydrate malabsorption is most often encountered in intestinal diseases. The clinical sequelae of malabsorption, the failure to utilize ingested nutrients, can be identical to malnutrition which is the failure to ingest required nutrients. Enteric infections result in intestinal dysfunction yielding malabsorption. In children, the most apparent presentation for malabsorption is failure to thrive and if malabsorption continues long enough, short stature. If the insult is more severe, there could be a transient decrease in the level of sucrase–isomaltase also, which leads to malabsorption of additional dietary sources of carbohydrate. Human immunodeficiency virus infection frequently results in malabsorption, but in addition to this mechanism, there may be repeated infectious insults and additional undefined problems that interfere with villi reg.