Lactose intolerance
Deficiency in the enzyme lactase, responsible for digesting the lactose found in dairy products, is common worldwide. While almost all infants are able to digest milk and other dairy products, many children lose their lactase enzyme by the ages of three to seven.
Symptoms range from minor abdominal discomfort and bloating to severe diarrhoea in response to even small amounts of lactose. The deficiency can be diagnosed with a lactose challenge test or Food intolerance test.