Lactase Deficiency (lactose intolerance)

Lactase deficiency results in the inability to digest lactose. Lactose is a type of sugar found in milk and other dairy products.

Lactose intolerance occurs when the small intestine does not make enough of the enzyme lactase.  As a result there is maldigestion of milk and dairy products.

Lactase deficiency is more common in people with Asian, Middle Eastern or Mediterranean ancestry.  It is rare for Caucasians to develop it.

Many people with lactase deficiency can usually tolerate some lactose with minimal symptoms.  Symptoms can mimic symptoms of irritable bowel syndrome (IBS) and can include:

  • Abdominal pain
  • Abdominal swelling
  • Flatulence
  • Diarrhoea.


Symptoms usually go away when you remove milk products or other lactose containing products from the diet.

For further information see the Gastroenterological Society of Australia website.