Lactose intolerance

Frequency and causes

Lactose intolerance is relatively common, affecting an estimated 15–25% of people in Europe.

Lactose intolerance is caused by a deficiency of the intestinal enzyme lactase, which splits indigestible lactose (milk sugar) into glucose and galactose. Only these two types of sugar can be absorbed from the intestine and into the body. In very rare cases, people may be born with insufficient levels of lactase – this is known as congenital lactase deficiency. More commonly, however, lactose intolerance or lactase deficiency does not develop until later in life, with genetic factors believed to be one of the causes of this. Various diseases in the gastrointestinal tract and other external influences can also disrupt lactase production, leading to lactase deficiency. If lactose is not fully digested or not digested at all, this can trigger a variety of symptoms.

Symptoms of lactose intolerance

Symptoms, which typically occur in cases of lactose intolerance, include bloating, increased flatulence, abdominal pain/cramps and diarrhoea. The intensity of these symptoms can vary significantly from person to person, depending on the nature of the lactase deficiency.

While even a small amount of lactose can trigger quite severe symptoms in some people, others can tolerate much larger quantities without experiencing any significant complaints. The severity of the symptoms is also influenced by the amount of lactose ingested.

Diagnosing lactose intolerance

There are various ways of diagnosing lactose intolerance.

A diet that completely cuts out food containing lactose can make the symptoms disappear (elimination diet), thus confirming a suspected case of lactose intolerance.

If the symptoms recur when the patient starts ingesting lactose again, lactose intolerance is also a very likely diagnosis (exposure test).

Another relatively reliable method for diagnosing lactose intolerance is the hydrogen breath test. If lactose digestion is disrupted, more hydrogen is emitted through exhalation after ingesting lactose, which is detected by measuring the level of hydrogen in the patient’s breath.

If the diagnosis is unclear, genetic analyses or tests on tissue samples from the intestine can also indicate whether a patient is lactose intolerant or not.

Of course, other diseases and disorders can also cause symptoms similar to those which occur as a result of lactose intolerance. This must be taken into consideration when carrying out diagnostic investigations.

Treatment options

Treatment for lactose intolerance generally involves avoiding foods and other substances containing lactose based on the patient’s symptoms. There is a wide range of special food products available which do not contain lactose and which are labelled accordingly. However, it is important to ensure that the patient’s diet still includes all the important nutritional elements. It is therefore a good idea to seek advice from a nutritionist.

In cases where it is not possible or feasible to avoid foods containing lactose, other medicines can be used which contain an enzyme that can digest lactose. If these are taken immediately before eating a meal containing lactose, they take over the function normally performed by lactase and help to reduce the symptoms of lactose intolerance.