Why should you test for lactose intolerance?
Lactose intolerance usually manifests itself in flatulence, abdominal pain, nausea and diarrhoea if those affected have consumed too much milk sugar (lactose). The connection between lactose intake and the onset of symptoms is not always clear.
However, it is important to know whether an intolerance to lactose is actually the cause of the symptoms. If this is the case, those affected can organize their diet in such a way that they have no or hardly any symptoms in future – by (largely) avoiding foods containing lactose such as milk and dairy products.
However, eating a lactose-free diet on mere suspicion is not a good idea: on the one hand, avoiding milk and dairy products also affects the supply of calcium – a mineral that is important for strong bones, among other things. Secondly, buying “lactose-free” specialty products (such as lactose-free yogurt, etc.) would put an unnecessary strain on your wallet.
So if you suspect that you cannot tolerate lactose, you should go to the doctor and find out for sure – with a test that can detect lactose intolerance with a high degree of probability.
How do you test for lactose intolerance?
- Hydrogen breath test (H2 breath test)
- Lactose tolerance test (blood sugar test)
- Genetic test
- Small intestine biopsy
Finally, there is also the option of testing for lactose intolerance on your own (lactose intolerance self-test).
A positive test result alone (e.g. in a breath test) is not sufficient for a reliable diagnosis. Lactose intolerance is only present by definition if the person concerned also develops symptoms as a result of ingesting lactose.
Hydrogen breath test
The most commonly used lactose intolerance test is the hydrogen breath test, also known as the H2 breath test. In this test, the hydrogen content in the exhaled air is measured before and after drinking a lactose solution. You can find out why the result allows conclusions to be drawn about lactose intolerance and which other intolerances can be detected using this method in the article H2 breath test.
Lactose tolerance test
You can also test for lactose intolerance using blood glucose levels. This method is an alternative if the hydrogen breath test does not help, but can also be used in conjunction with it.
How the lactose tolerance test works
In contrast, this test is negative in people with lactose intolerance – there is little or no increase in blood glucose levels because the lactose cannot be broken down and absorbed in the intestine.
How the lactose tolerance test is carried out
Before the test begins As with the hydrogen breath test, the patient ingests a defined lactose solution. Before and at certain intervals for up to three hours afterwards, their blood sugar level is measured. Normally, this rises by more than 20 mg/dl as a result of the lactose intake. If this increase does not occur or is less, the patient is lactose intolerant.
Another indication of lactose intolerance is if the test person develops typical symptoms (abdominal pain, flatulence, diarrhea, etc.) after drinking the lactose solution.
Problems with the lactose tolerance test
This lactose intolerance test can be an alternative to the hydrogen breath test, but is less accurate and therefore not the method of choice. In addition, the measured values can be falsified in diabetics.
Genetic test
Small intestine biopsy
In principle, it is also possible to take a tissue sample from the small intestine in order to measure the activity of the lactase present. However, this is generally only done as part of scientific studies.
Lactose intolerance self-test
Some people who suspect that they cannot tolerate lactose carry out a diet/exposure test on their own initiative: They avoid foods and drinks containing lactose for some time to see if this improves their symptoms. If this is the case, it indicates lactose intolerance. The next step is to drink a glass of lactose dissolved in water (available in drugstores and pharmacies) – in other words, to expose yourself to lactose. If lactose intolerance is actually present, the typical symptoms will return after a short time.
If carried out correctly and consistently, the lactose intolerance self-test provides a thoroughly reliable result. However, mistakes are often made because the diet is not followed strictly enough. This is why a lactose intolerance test by a doctor is still the most reliable proof.
