Lactose intolerance • Symptoms, test & tablets

If your stomach hurts or feels bloated after a few sips of milk or yogurt, this may be due to lactose intolerance. Those affected have difficulty digesting milk sugar (lactose). Find out how it comes about, what signs point to it and which test can be used to detect food intolerance.

An estimated 15 to 20 percent of people in Germany cannot tolerate lactose. But that doesn’t mean that all dairy products are taboo for them. Small amounts are often tolerated.

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Lactose intolerance: Unexpected foods with lactose

What is lactose intolerance?

Lactose intolerance (also known as milk sugar intolerance or lactose malabsorption) is a food intolerance in which those affected cannot tolerate any or only small amounts of lactose-containing foods. Lactose is a milk sugar that is naturally only found in milk and the products made from it. People with lactose intolerance develop digestive problems such as flatulence or abdominal pain immediately after consumption up to a few hours later.

Lactose intolerance must be distinguished from a food allergy. In the case of a cow’s milk allergy, the body does not react to the lactose, but to the smallest amounts of proteins.

cause of lactose intolerance

The cause of lactose intolerance is a lack of lactase. Normally, the enzyme breaks down the double sugar lactose into the two simple sugars galactose and glucose in the small intestine. However, due to a reduced or missing activity of the enzyme, the lactose reaches the large intestine uncleaved. Here the sugar is broken down by bacteria into lactic acid and gases. These fermentation products are responsible for complaints such as flatulence.

forms of lactose intolerance

Depending on the trigger of lactose intolerance, three forms are distinguished:

  • Primary lactase deficiency: The most common form is a genetically determined decrease in lactase over the course of life. During breastfeeding, nature ensures that infants tolerate breast milk well. In the course of life, the activity of lactase decreases continuously in most people, so that an intolerance to lactose occurs in adulthood. In Germany, about 15 to 20 percent of adults do not tolerate lactose well, in Asian countries it is even 80 to 100 percent.

  • Secondary lactase deficiency: The intolerance is caused by other diseases such as Crohn’s disease, ulcerative colitis or celiac disease. Stomach and intestinal surgery can also lead to lactose intolerance.

  • Congenital lactase deficiency: In rare cases, newborns are completely missing the gene responsible for lactase production. Then it is particularly important for those affected to follow a lactose-free diet.

These symptoms may indicate lactose intolerance

The typical symptoms of lactose intolerance occur as a result of the lactose remaining in the intestine and the resulting increased formation of gases:

These symptoms can appear immediately after consuming milk and milk products such as yoghurt, butter, cheese and cream, or a few hours later. Depending on the amount of lactose ingested and the severity of the lactase deficiency, these symptoms vary in severity. Some people with lactose intolerance also show non-specific symptoms such as exhaustion or dizziness. Other sufferers feel unconcentrated and tired after drinking milk.

Skin symptoms such as hives, breathing problems or a sudden drop in blood pressure are more likely to indicate a cow’s milk allergy.

Tests to diagnose lactose intolerance

If there is a suspicion of lactose intolerance, various examination methods are available.

Exit and provocation test

In this self-test, those affected completely abstain from milk and milk products for at least two to four weeks. If symptoms improve during this time and worsen when lactose is reintroduced into the diet, this is a clear indication of lactose intolerance.

H2-Breath test to diagnose lactose intolerance

The breath test is based on the fact that in the case of lactose intolerance, the milk sugar in the intestine is broken down into lactic acid and gases such as hydrogen (H2) is converted. The hydrogen is absorbed into the bloodstream via the intestinal mucosa and exhaled via the lungs. Before the test, patients are given an amount of lactose that depends on their body weight on an empty stomach. Then they have to blow into a breath test device for about half an hour. If the amount of hydrogen in the breathing air exceeds a certain value, this is considered a reliable diagnosis of lactose intolerance.

blood glucose history test

A blood test can be carried out as an alternative or in addition to the breath test. Here, too, patients must drink previously dissolved lactose on an empty stomach. Before the test and one and two hours after, blood is drawn to measure the sugar level in the blood. If the content does not increase or only slightly, this indicates that the lactose could not be processed in the intestine and that there is therefore a lactose intolerance.

Genetic Test

In the genetic test for lactose intolerance, the doctor tests a sample of the oral mucosa or a small amount of blood. In this way it can be determined whether there is a genetic defect in lactase. This enzyme is responsible for breaking down milk sugar.

Treatment and tips for lactose intolerance

If the lactose intolerance is due to another disease, for example chronic inflammatory bowel disease, this should be treated specifically. In some cases, secondary lactose intolerance can be cured or alleviated in this way. In the case of primary lactose intolerance, a change in diet and the intake of lactase enzyme preparations can be useful.

Lactose-free and low-lactose diet

The diagnostic tests can be used to determine whether there is lactose intolerance, but not how much lactose is actually tolerated. Many sufferers do not have to give up dairy products entirely. Some types of cheese, such as Parmesan, also contain hardly any lactose due to the way they are processed. To find out which products are tolerated, nutritional advice can be useful.

Furthermore, the following procedure can help to find out which and how many dairy products can be eaten:

  1. grace period: First of all, products containing lactose should be avoided completely for two to four weeks. Instead of milk, you can drink plant-based milk substitutes such as rice, almond, soy or oat milk. Products that contain less than 0.1 grams of lactose per 100 grams are considered “lactose-free”. Some types of cheese such as goat’s and sheep’s cheese do not exceed this lactose value and are considered lactose-free.

  2. Test phase: Gradually, foods containing lactose can be introduced into the daily diet. Food and complaints should be documented in detail.

  3. Long-term nutrition: The amount of lactose determined in the test phase can be used as a guideline for long-term nutrition. However, most of those affected have to pay attention to a low-lactose diet on a permanent basis and should avoid foods with a high lactose content (more than five grams per 100 grams) if possible. These include processed cheese, condensed milk, or white chocolate. Butter, feta cheese or hard cheese, on the other hand, have a low lactose content and can usually be consumed without any problems.

Tablets for lactose intolerance

Lactase enzyme preparations are not suitable as a substitute for a low-lactose diet. However, they can improve the tolerability of foods containing lactose. The enzyme lactase is always taken before meals containing milk. The tablets are available in pharmacies and drugstores without a prescription.

However, the dosage of the tablets varies greatly depending on the severity of the lactose intolerance and is therefore difficult. Every person affected has to find out for themselves how many lactase tablets they need before which meal. In the course of lactose intolerance, the dosage may also need to be adjusted if the symptoms worsen. In addition, the tablets from different manufacturers contain different amounts of lactase.

Course of lactose intolerance

Lactose intolerance cannot be cured. However, those affected by the most common primary intolerance can live a completely normal life if they avoid foods containing lactose after the diagnosis or take the missing enzyme lactase via tablets. Alternatives include products made from soya or special lactose-free products. The course of the secondary form depends on the underlying disease. If this can be treated, the symptoms of lactose intolerance usually also improve.

In both the primary and secondary forms, the restricted diet can lead to a lack of calcium and vitamin D. The calcium and vitamin D status should therefore be checked regularly so that the nutrients can be taken in tablet form if necessary.

However, the congenital form of lactose intolerance can be life-threatening for newborns if not diagnosed quickly. The sick infants are endangered by even the smallest amounts of lactose. Breast milk cannot be processed in these cases either. There is a risk of dehydration in the baby and serious brain damage if diagnosis and appropriate treatment are initiated too late.

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Source: Lifeline | Das Gesundheitsportal by

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