Digestive Disorders > Intolerances > Fructose Intolerance

Fructose intolerance test – at home and at the doctor's (including online self-test)

Dr. med. Andre Sommer

Dr. med. Andre Sommer

About a third of Germans suffer from fructose intolerance. There are a variety of different tests that indicate the presence of this condition. In the text you will learn which fructose intolerance tests are available and how you can carry out an intolerance test yourself at home.

What tests are there for fructose intolerance?

Food intolerances, which also include fructose intolerance, are demonstrated in various ways. There are basically three different test methods:

  1. Food diary
  2. Self-tests and provocation tests
  3. H2 breath test

Keeping a food diary is like an initial test. Such a diary is well suited to get a rough overview of your own diet and possible intolerances.

There is also a self-test for fructose intolerance. With the help of these tests, which usually consist of specific questions, important information can be obtained as to whether there is a fructose intolerance. Reizdarm.one offers a self-test for fructose intolerance, which you can take here.

There are also tests performed by a doctor. These tests include, for example, the fructose provocation test and the H2- breath test, sometimes called a fructose breath test.

How is a food diary structured?

All meals are meticulously recorded in a food diary over a longer period of time - for example over two weeks. In addition, notes on the state of health and possible complaints are entered in an additional column for each meal. This provides a good overview of the meals after which the symptoms appear, the circumstances that contribute to the symptoms, and which foods are often associated with the symptoms. We recommend the free nutrition and symptom diary from Cara Care. Download the CARA CARE app here.

With the food diary, you can narrow down your suspicions of certain intolerances and collect first indications about whether your case might be an intolerance.

If it is noticed in the diary, for example, that symptoms occur after eating foods containing fructose such as fruit juices, nuts, honey or ketchup, the suspicion of fructose intolerance increases.

How does the fructose intolerance self-test work?

There are several ways to do a self-test for fructose intolerance. Reizdarm.one offers an interactive test which you can find here.

In this test you will be asked some questions about your diet and your symptoms. The questions were carefully selected to cover as wide a range of different symptoms as possible and to allow an accurate statement. Your answers to the questions asked in the test make it possible to determine whether you have a fructose intolerance.

Here is the test.

How long does the self-test take?

The self-test for fructose intolerance consists of a few questions that you should answer conscientiously. Generally, filling in the questions takes no more than fifteen minutes. You will then receive the results of the evaluation by email. The self-test is a good way to get important information about the presence of fructose intolerance in a short amount of time.

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How reliable is the self-test?

The questions asked as part of the self-test for fructose intolerance are specifically selected so that they cover a wide range of symptoms. This will make an accurate statement about the character and scope of your complaints possible. Since the questions of the self-test are based on the most important symptoms and complaints of fructose intolerance, they allow a reliable statement to be made as to whether the patient in question is fructose-intolerant.

Such a self-test does not replace extensive diagnostics by a doctor. However, it gives important indications on the presence of the disease and can help to take the next steps. If the self-test reveals suspected fructose intolerance, the presence of this disease is very likely. It is therefore recommended you carry out such a self-test before visiting the doctor to collect important information that you can bring to the conversation with your doctor.

Are there other self-tests for fructose intolerance?

In addition to the questionnaires, there are other ways to do a test for fructose intolerance yourself at home.

To test whether you are intolerant to fructose at home, you can drink 250 ml of apple juice in the morning, before your first meal and on an empty stomach. It is important that this is clear, not (naturally) cloudy apple juice.

After that you should wait at least 30 minutes and see if you have any symptoms. This may be a sudden urge to use the bathroom with diarrhea, abdominal pain or flatulence. Also strikingly loud, so-called "gurgling" bowel sounds are an important symptom.

If you experience one or more of these symptoms, it is very likely that you are suffering from fructose intolerance.

Please note that you should not carry out such a self-test if you already know that you react to the consumption of fruit juices, fruit or fructose with severe symptoms. If you already have (congenital) fructose intolerance, you should also not do a self-test.

How does the doctor test for fructose intolerance?

Click here for the self-test.

In medical practice, a test is often used that is very similar to the self-test at home. It is called the fructose provocation test.

The patient is given 25 g of fructose in a special fructose solution for drinking. After a while, the symptoms that arise are identified and the diagnosis of fructose intolerance is made. In some cases, another intolerance test is used, the so-called H2 breath test.

Is an H2 breath test reliable?

Many providers, especially on the Internet, promise to quickly and safely make a definitive statement about the existence of a fructose intolerance with a hydrogen breath test. However, such a test is not without controversy, and the interpretation of its results by medical professionals is discussed controversially.

That is because the evaluation of such a test often depends on the subjective impressions of the person performing it. In addition, some aspects of food intolerance, such as the interplay between fructose intolerance and sorbitol, are completely ignored. It is therefore very important for those affected to only rely on trustworthy providers and never to make the diagnosis solely by means of such a breath test. Rather, it is the combination of different tests that ultimately brings security and can make a clear diagnosis.

Which doctor can do a fructose intolerance test?

Lots of GPs and general practitioners can offer their patients a fructose intolerance test. Specialists in internal medicine, especially gastroenterologists, who specialize in the gastrointestinal tract often offer fructose intolerance tests in their practices.

What is the best way to proceed if you suspect you are fructose intolerant?

If you suspect that you are fructose intolerant, it is advisable to proceed as follows:

  1. The first step is to keep a food diary for a while in order to identify the symptoms and collect important information about their triggers.
  2. In addition to the food diary, it is helpful to do a self-test for fructose intolerance. With the help of such a test, the suspicion of fructose intolerance can be confirmed.
  3. The last step in the program is a doctor visit. The doctor can confirm the diagnosis and initiate the treatment of the disease with you.

    Since in the case of fructose intolerance, nutrition is responsible for the occurrence of the symptoms, many sufferers also take advantage of professional nutritional advice in order to optimally adapt their everyday life and their eating habits to the disease. We have developed a special nutritional therapy for food intolerances. Together with your nutritionist, you will find out here what you can tolerate well and how to establish eating habits that are really good for you. Arrange a free informational meeting here and find out more.

Velten, F. W., & Bayerl, C. (2007). Fructosemalabsorption - die andere Seite gesundheitsbewusster Ernährung. Aktuelle Dermatologie, 33(10), 373-378. Online: https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-2007-966697

Reese, I. (2012). Diagnostisches und therapeutisches Vorgehen bei zwei populären, aber sehr unterschiedlichen Nahrungsmittelunverträglichkeiten - Fructosemalabsorption und Histaminintoleranz. Therapeutische Umschau, 69(4), 231-237. Online: https://econtent.hogrefe.com/doi/abs/10.1024/0040-5930/a000279

Simren, M., & Stotzer, P. O. (2006). Use and abuse of hydrogen breath tests. Gut, 55(3), 297-303. Online: https://www.ncbi.nlm.nih.gov/pubmed/16474100

Dr. med. Andre Sommer

Dr. med. Andre Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara Care.

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