Lactose intolerance  >> back to the newsletter overview

Roughly one in five Germans is suffering from lactose intolerance and cannot take any milk sugar naturally contained in milk and dairy products. This even applies to more than 80% of the world population. The affected ones are either lacking or have an insufficient level of the enzyme responsible for decomposing milk sugar in the bowels. The consequences of milk sugar consumption are then often very unpleasant and range from nausea and vomiting to fatigue, diarrhea and abdominal cramps.

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What are the factors responsible for lactose intolerance?

Lactose is Latin for milk sugar. Lactose intolerance is the organism’s inability to correctly digest milk sugar. It is usually broken down by an enzyme (lactase) into two monosaccharides – galactose and glucose (dextrose) – inside the small intestine. A protein then transports these monosaccharides into the body through the mucous membrane of the bowels. If the enzyme is lacking or only insufficiently available, milk sugar cannot be split, or at least not completely, and reaches the colon where bacteria process the milk sugar and form gases leading to the typical symptoms of lactose intolerance.

What forms of lactose intolerance are there?

Congenital lactose intolerance

This is a genetically determined form of complete lactose intolerance: it is caused by a genetic defect strongly limiting or totally inhibiting the formation of lactase. It is a very rare autosomal recessive disorder that already affects newborn children and cannot be cured.

Primary lactose intolerance

This is the most common form of lactose intolerance. It is also genetically determined and can increasingly be found in regions with a high insolation. Under this condition, the ability to digest lactose diminishes with age. 70% of all Europeans are affected already at the age of 60. The reason for the reduced enzyme production in adults is an autosomal recessive gene mutation that cannot be cured.

Secondary lactose intolerance

This form of lactose intolerance is not genetically determined; it is a disorder of the mucous membrane of the bowels. As mentioned before, the lactase enzyme is released through the mucous membrane of the small intestine. If this layer of the bowel is damaged by other diseases or medication (such as a harmful bacterial colonization in the gut flora, taking antibiotics during a longer period of time, forms of intolerance like fructose malabsorption, Crohn’s disease, coeliac disease, alcoholism), it is no longer able to release lactase. Usually, secondary lactose intolerance is a temporary condition. It is curable and passes with eliminating the cause of the bowel damage.

Which symptoms can be detected and how do they develop?

If the enzyme does not split the lactose, it immediately reaches the colon where bacteria comes into play. Lactic acid, short-chain fatty acids (acetic acid, butyric acid, …) and gases such as hydrogen, carbon dioxide or methane figure among the waste products of the bacterial decomposition. As these substances are formed in larger amounts, they can lead to abdominal pain, flatulence, nausea and diarrhea.

Not to be confused with milk allergy!

It is essential to differentiate between lactose intolerance and milk allergies (casein, lactalbumin, cow’s milk allergy). The latter refer to allergic reactions to certain ingredients of milk. Even the smallest amounts (traces) can cause symptoms. Lactose intolerance differs from allergies in this respect as small amounts are usually harmless.

What can you do to identify a potential lactose intolerance?

If you suspect suffering from lactose intolerance, we recommend writing a symptoms journal. Write down when and what you are consuming, and when and which symptoms appear consequently. This will make it easier for the physician to narrow down the symptoms pattern.

What can we do for you?

If you think you may suffer from lactose intolerance, you should get in contact with an internal medicine specialist (gastroenterologist). Making a diagnosis in cases of lactose intolerance is a complex issue as symptoms are not always clear. There may as well be other causes of gastrointestinal disorders. We will first do some basic tests (blood count, inflammatory parameters, ultrasound diagnostics) to try and exclude other potential causes of the symptoms. If these substantiate an initially suspected lactose intolerance, a breath test is advisable measuring the hydrogen concentration in the exhaled air after the patient had to drink up a lactose solution. In case of lactose intolerance, this concentration is usually elevated. If this confirms lactose intolerance, a change in the patient’s nutrition habits will become necessary. We then recommend seeing a nutritionist to jointly set up a nutrition plan in accordance with your individual needs.

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