A condition in which there is a lack of lactoe, a enzyme that breaks down lactose (milk sugar), in the cells of the small intestine. Lactose deficiency lessens ability to digest lactose. This is called lactose intolerance and often appears in adulthood or adolescence; hardly ever it is present from birth (particularly in premature babies). Lactose deficiency can also arise temporarily after gastroenteritis or treatment with antibiotics especially in small children.
The undigested lactose ferments in the intestines, causing symptoms like abdominal cramps, flatulence, bloating, and diarrhoea.
The condition can be established by testing faeces for the presence of lactose. Alternatively, an exclusion diet can be used, in which consumption of dairy products is ceased for a few days, then resumed to see if this creates any changes in the symptoms.
Treatment is with a lactose free diet. Certain people are able to tolerate little amounts of dairy products but others must completely avoid dairy products, including milk, cheese, butter, cream, and yoghurt. It is possible to obtain milk products that in which the lactose has already been broken down, and enzyme supplements holding lactose, which can be added to milk or taken with food.