Fructose Intolerance

Fruit is generally considered to be a healthy food. But what if you can not tolerate fruit?

What is fructose?

Fructose, like glucose, is a simple sugar. It is found, for example, in fruit, various vegetables, honey and household sugar (sucrose). Household sugar is a compound sugar composed of fructose and dextrose.

Causes and symptoms

Fructose intolerance disrupts the absorption of fructose in the small intestine. Due to incomplete absorption, the sugar moves to the large intestine, where it is broken down by bacteria into hydrogen, carbon dioxide and short-chain fatty acids. This causes typical complaints such as flatulence, bloating, nausea, abdominal pain and diarrhea. Whether the symptoms are severe or mild depends on how much fructose has been absorbed and how severe the ailment is. Some people react quickly to small amounts of fructose, while others tolerate their "personal dose" symptom-free.


Fructose intolerance is detected by means of an H2 breath test. The patient drinks a defined amount of fructose solution under medical supervision. By measuring the patient's breath, it can then be determined whether the typical intestinal gases indicating a disrupted absorption of fructose are detectable. In order to determine the individually tolerated amount of fructose, the patient must avoid all foods containing fructose for about 2 to 3 weeks. If the patient is then symptom free, the consumption of foods containing fructose can be gradually increased in a test phase. The amount of discomfort is observed at each stage.


Unfortunately, fructose intolerance cannot be treated with medication. The only thing that can help is a low-fructose diet that is constantly followed, depending on the type and severity of the ailment. It is important that not only fructose and fructose-containing foods are avoided, but also drugs or infusions containing these sugars.

The sugar alcohol sorbitol is the alcohol form of fructose and should also be avoided. It occurs naturally and, like fructose, is used as a sugar substitute, especially in dietetic foods.

The tolerance of fructose is improved by the presence of glucose!

In principle, a low-fructose and sorbitol-free diet should be maintained, but it is not necessary to avoid fructose altogether. If glucose (dextrose) is present in the intestine at the same time, fructose can be much better absorbed. If the ratio of glucose to fructose is greater than or equal to 1, the corresponding food is generally compatible.

Low-fructose foods include:

  • Cereal products from ground flour
  • Potatoes
  • Dairy products e.g. sour milk, curd cheese, cheese
  • Vegetables: Spinach, chard, chicory, leaf salad, kitchen herbs, spices, avocado, rhubarb, mushroom
  • Nuts (except peanuts)
  • Meat, poultry, fish and eggs
  • Water, coffee and tea
  • Butter, margarine, vegetable oils
  • Glucose

Fructose-containing foods include:

  • All types of fruit, dried fruits and fruit juices (e.g. vitamin drink)
  • Artichokes, eggplant, broccoli, carrots, pumpkin, tomatoes
  • Honey
  • Fruit tea and fruit juice
  • Wine