Milk and other dairy products contain a sugar or carbohydrate called lactose. Normally, the body breaks
down lactose into its simpler components with the help of the enzyme lactase. Most mammals stop
producing lactase when they are weaned; humans, however, continue to produce it throughout life. Without
enough lactase, a person can have digestive problems like abdominal pain and diarrhoea. This is known
as lactose intolerance or lactase deficiency.
Symptoms of lactose intolerance include:
- Abdominal pain
- Abdominal swelling
Symptoms of lactose intolerance are often confused with symptoms of irritable bowel syndrome (IBS).
People with IBS are not lactose intolerant, but tend to have difficulty tolerating fat.
Causes of lactose intolerance
- Lactose intolerance is largely genetically determined. Some causes include:
- Congenital – this is the main cause so you can blame your genes if you have less lactase than usual.
- Gastroenteritis – this can strip the intestines of lactase for a few weeks.
- Parasitic infection – this can temporarily reduce lactase levels.
- Iron deficiency – lack of iron in the diet can interfere with lactose digestion and absorption.
Various methods may be used to diagnose lactose intolerance, including:
- Hydrogen breath test – this tests the amount of hydrogen that is breathed out. When lactose is fermented by bacteria in the bowel, instead of being converted by lactase, more hydrogen is produced.
- Elimination diet – this involves removing foods that contain lactose to see if the symptoms improve. If the symptoms reappear once the foods are reintroduced, then lactose intolerance is most likely the cause.