What is lactose intolerance

Lactose intolerance is a condition that occurs when the body is unable to produce enough of the lactase enzyme to digest lactose, the predominant sugar found in milk.

Produced by the cells that line the small intestine, lactase breaks down milk sugars into a simpler form so that they can be easily absorbed into the bloodstream. When the body cannot produce enough lactase some or all of the lactose passes through into the large intestines where bacteria will attempt to break it down. This process, called fermentation, generates lactic and other organic acids, short-chain fatty acids, carbon dioxide, hydrogen gas and methane, which together cause the symptoms of lactose intolerance.

Lactose intolerance can occur in newborns and young babies, but is more likely to develop in later life.