Which of the following enzymes becomes deficient following an episode of severe infectious gastroenteritis:

Ans. A. LactaseLactose intolerance is an inability to digest lactose, the main sugar in milk, which gives rise to gastrointestinal symptoms. Lactose intolerance is caused by a deficiency of the intestinal enzyme lactase that splits lactose into two smaller sugars, glucose and galactose, and allows lactose to be absorbed from the intestine. Lactase deficiency can be either congenital or acquired. Congenital lactase deficiency due to complete lack of the enzyme is a rare condition that presents with severe symptoms in newborns. In addition, lactase malabsorption may be secondary to acquired conditions including small bowel bacterial overgrowth, infectious enteritis (i.e. giardiasis), or mucosal damage due to coeliac disease, inflammatory bowel disease, drugs, gastrointestinal surgery, short bowel syndrome, or radiation enteritis, conditions that lead to either reduction of absorptive capacity or downregulation of lactase expression in the small intestine. Typical gastrointestinal complaints resulting due to lactose intolerance are diarrhoea, nausea, bloating, borborygmi, and abdominal pain.