Lactose intolerance is also known as milk sugar intolerance. It is a food intolerance to milk sugar (lactose) that is caused by a disorder in the enzyme balance. There is a deficiency in the body's own enzyme lactase. As a result, it is unable to digest the lactose that occurs naturally in milk and dairy products.
As a result, people with lactose intolerance experience symptoms after consuming milk and dairy products such as
- milk powder,
- cheese,
- yoghurt,
- curd cheese,
- cream,
- ice cream or
- chocolate
Complaints such as
- flatulence,
- nausea,
- abdominal pain and
- diarrhea
and diarrhea.
Milk sugar (lactose) is a disaccharide. It is normally broken down by lactase into its two components glucose and galactose. It can then pass through the intestinal wall into the blood.
Lactase is formed in the mucous membrane of the small intestine. If the small intestine produces too little lactase or none at all, this breakdown of lactose does not take place or only to a limited extent.
However, the small intestine cannot absorb unsplit lactose. The lactose therefore remains in the small intestine, where it binds water and causes diarrhea.
On the other hand, it continues into the large intestine, where bacteria convert it into
- lactic acid,
- acetic acid,
- carbon dioxide and
- hydrogen
which leads to the flatulence typical of lactose intolerance.
The incidence of lactose intolerance varies from region to region. In Germany, it is estimated that around 15 percent of people suffer from a more or less pronounced lactose intolerance. Lactose intolerance is also common in other European countries and in America.
Lactose intolerance is particularly widespread in Asian countries and in sub-Saharan Africa. Here, around 90 percent of people have a deficiency of the enzyme lactase, which is needed to digest lactose.
Lactose intolerance is always caused by a deficiency of the enzyme lactase in the mucous membrane of the small intestine.
A distinction is made between two forms:
- primary lactase deficiency is genetically determined
- Secondary lactase deficiency is acquired in the course of life
In the primary form of lactose intolerance, the lactase deficiency is either present from birth - although this is very rare. It is far more common for it to increase over the course of a person's life.
Secondary lactose intolerance develops
- as a result of diseases of the gastrointestinal tract such as chronic inflammatory bowel disease or
- as a consequence of treatment, for example after operations on the gastrointestinal tract or after prolonged use of medication such as antibiotics or cytostatics.
The symptoms of lactose intolerance usually occur within a few hours of consuming milk and dairy products.
Typically, lactose intolerance then causes symptoms such as
- cramp-like abdominal pain,
- flatulence,
- loud intestinal noises,
- a feeling of fullness,
- diarrhea,
- constipation,
- strong urge to defecate,
- nausea and
- vomiting.
Nausea and intestinal discomfort are common symptoms after consuming dairy products with lactose intolerance © bit24 | AdobeStock
However, atypical symptoms that are not related to the digestive tract can also occur with lactose intolerance. These include, among others
- Headaches,
- dizziness,
- tiredness,
- fatigue,
- aching limbs or
- skin problems such as acne.
The severity of the symptoms depends on
- whether the affected person suffers from mild or severe lactose intolerance and
- the amount of lactose-containing foods they have consumed.
Some sufferers can tolerate at least small amounts of lactose without developing symptoms. Others are only symptom-free if they completely avoid lactose.
To diagnose lactose intolerance, the following tests are available
- the self-test,
- the H2 breath test and
- the lactose load test
various tests are available.
In the self-test, the affected person first abstains from consuming dairy products for a few days and then drinks a glass of milk. If typical symptoms such as abdominal pain or diarrhea occur immediately afterwards, lactose intolerance is suspected. If the symptoms disappear after three to four weeks without consuming dairy products, the diagnosis is as good as confirmed.
The most widely used test for diagnosing lactose intolerance is the H2 breath test (H2 = hydrogen). During the decomposition of lactose, gases are produced, including colorless and odorless hydrogen. Its content in the breath is measured before and after ingestion of a lactose solution at various intervals. It is also observed whether the patient develops diarrhea or signs of flatulence.
Another method that can be used to diagnose lactose intolerance is the lactose load test. In this test, the patient is also given a lactose solution. A blood analysis is then carried out to measure how much glucose (broken down lactose) is contained in the blood. If the amount is too low, it can be assumed that the patient is lactose intolerant.
Lactose intolerance is usually treated by changing to a low-lactose or lactose-free diet. Those affected should therefore largely or completely avoid the consumption of milk or dairy products.
Instead, they should opt for lactose-free or lactose-reduced foods. These include soy products or lactose-free dairy products. With the latter, there is no difference in taste apart from the slightly sweet taste. The sweet taste is caused by the industrial breakdown of lactase.
Lactose intolerant people should largely avoid dairy products © bit24 | AdobeStock
Those who completely avoid dairy products should take calcium supplements if necessary to prevent possible deficiency symptoms.
If you are lactose intolerant, taking lactose in the form of a dietary supplement can also be helpful. The missing enzyme is available in liquid form or in tablet form. It can be taken before a meal containing milk or added to milk.
If it is a secondary lactose intolerance, it is important to treat the underlying disease.
Lactose intolerance is often chronic and cannot usually be cured. However, it is not life-threatening. Life expectancy is not limited by lactose intolerance.
However, those affected should adapt to a lifelong low-lactose or lactose-free diet. If this diet is followed consistently, most sufferers can lead a symptom-free life.
