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What is lactose? What are the causes of lactose intolerance?
Lactose is a disaccharide sugar derived from galactose and glucose that is found in milk. Lactose makes up around 0-8% of milk (by weight), although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from lac or lactis, the Latin word for milk, plus the -ose ending used to name sugars. It has a formula of C12H22O11.

  • Lactose is a type of sugar found in milk. Lactase is a protein, an enzyme that is produced in the small intestine - it breaks down lactose. Individuals with lactose intolerance do not produce enough lactase.

  • People with adequate amounts of lactase can break down lactose into glucose and galactose (a type of sugar) which are then absorbed into the bloodstream.

  • In people with low levels of lactase, the lactose is not broken down and does not absorb into the bloodstream, instead it moves into the large intestine (colon). Bacteria in the colon react to the lactose, triggering symptoms.


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