Letzte Aktualisierung am 9. September 2024 von Dr. Michael Zechmann-Khreis
Have you just been diagnosed and don’t know your way around? What happens next? What else can you eat? Here we explain the basics of intestinal fructose intolerance (fructose malabsorption) to all newcomers. This article is a first introduction to the topic, which should clear up any initial confusion.
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Fructose intolerance or fructose malabsorption
A distinction is made between hereditary (inherited) fructose intolerance and fructose malabsorption. In hereditary fructose intolerance, there is a problem with fructose processing from the start of complementary feeding, which means that this form no longer develops in adulthood. On the nmi portal, we only talk about fructose malabsorption. In this form, fructose is not absorbed properly, which leads to symptoms. As soon as symptoms occur, we speak of intestinal (digestive) fructose intolerance.
To-dos after the diagnosis
First of all, you should make an appointment with a state-approved nutritionist who is familiar with food intolerances. A doctor should also check whether you have any other intolerances.
Keep a symptom and food diary
It is very important to keep a so-called symptom and food diary. This makes it much easier for the treating doctors or nutritionists to narrow down the symptoms. Such a diary is useful because the symptoms can often occur with a time delay (several hours). As a result, it is often impossible to recognize the correct connection between food and symptoms. In practice, this is a major problem, as many sufferers associate their symptoms with food, which often has nothing to do with their symptoms. Important: In the case of fructose intolerance, symptoms do not occur immediately after eating, but only once the fructose has reached the large intestine. This takes between 20 minutes and several hours.
The three-phase program
| 1. elimination diet | 2nd test phase | 3. permanent nutrition |
|---|---|---|
| Strictly low-fructose diet, “fructose fasting” | Testing individual tolerances | Fructose-reduced, but not fructose-free diet! |
| Avoid sugar, fruit and vegetables. | Test a new food every 2 days, test sugar alcohols | Always push your own limits; also do not avoid sugar alcohols completely. |
| Duration: approx. 2 weeks | Duration: max. 6 months | Fructose fasting once a year for approx. 2 weeks |
Short & sweet: Eating with fructose intolerance
- Enzyme preparations: Only use in exceptional cases! These preparations should not be used as permanent medication, as they convert the fructose in the chyme into glucose and so there is too much glucose (dextrose) in the digestive tract in the long term. This can promote intestinal colonization and upset the insulin balance. But that’s no problem when going out, on vacation or in exceptional cases!
- Some FAQs about fructose intolerance
- Deficiency symptoms are not to be feared during the elimination diet
- You should eat a balanced diet for the rest of the year
- Mineral-rich mineral water (preferably alkaline) and tap water should be drunk a lot.
- Soft drinks are poorly tolerated; light drinks are usually well tolerated
- Dietary fiber must be tested individually, but should never be completely eliminated from the diet; therefore, if tolerated, always use whole grain flour and whole grain rice (please test beforehand!)
- Prebiotic foods (containing oligofructose, inulin …) are good for the intestinal microbiome and can be consumed without any problems in the permanent diet, as the fructose is bound here and cannot be absorbed anyway
- Eat fruit and vegetables at least 3 times a week. The “Ask Ingrid!” app helps with this.
- Fruit is best consumed after a main meal and more in the afternoon
- Do not give up fructose completely after the elimination phase! This is damaging and exacerbates the problem. Find out individually how much fructose you can tolerate and keep questioning this amount and testing your limits.
- Dextrose improves the absorption of fructose. Caution: Do not use dextrose too often! It is better to avoid food containing fructose. Glucose should only be used as an “emergency solution”, as there is a risk of promoting insulin resistance.
Do I have to pay attention to the exact amounts of fructose in grams?
No! The exact calculation of fructose and glucose contents is not expedient and is not recommended. During the test phase, you can learn to listen to your body and assess the tolerance of foods. Our tables and lists with the sugar content are useful for this. The same goes for our “Ask Ingrid!” app. However, they should not be used to calculate exact amounts of fructose or glucose and then live according to these amounts! Anyone who does this runs the risk of worsening their own fructose tolerance.
Is fruit compatible with fructose intolerance?
Theoretically, you can eat any fruit that contains more glucose than fructose but less fructose in total. Papaya, banana or tangerine are usually well tolerated. You can find a detailed list of compatible foods in the “Ask Ingrid!” app.
Can you eat ready-made products and sorbitol?
Certain sugar alcohols presumably block the transport system in the intestine, which functions poorly in people with fructose intolerance. These substances should therefore be avoided. These include sorbitol (sorbitol), mannitol and other, but not all, sugar alcohols. These substances are often found in chewing gum, sweets and ready meals, but must be declared in the list of ingredients on the packaging.
What about the sugar?
Normal household sugar can be consumed in small quantities by most patients on a permanent diet without any problems!
Table sugar (sucrose) is a disaccharide. It consists of one molecule of fructose and one molecule of glucose. As glucose facilitates the absorption of fructose, household sugar is usually well tolerated in moderation (after the elimination diet).
Can I drink alcohol?
Lager beer can be tolerated well, wheat beer (cloudy beer) is often less well tolerated. Lager beer can also be diluted with soda water like a spritzer (“sour shandy”). Dry wines are usually relatively well tolerated in small quantities, sweet wines usually less so. As a general rule, the sweeter an alcoholic drink is, the less well tolerated it is. Alcohol irritates the intestines and makes them more permeable. An irritated bowel should therefore not be additionally burdened with alcohol.
Can I eat everything again with enzyme preparations?
No. The preparations on offer convert fructose (no sugar alcohols!) into glucose in the digestive tract. They should only be used in exceptional cases and are not intended for continuous use.
Which diagnostic methods are reliable?
Currently, the only way to test is via the H2 breath test (with 25g of fructose dissolved in water; to be carried out at the doctor’s, not at home). Home tests or other diagnostic methods such as bioresonance, spit test, hair analysis, pendulum or the like cannot detect fructose intolerance.
Sources include:
Stryer, L., Biochemie, Specktrum Akademischer Verlag, 4th edition
Zechmann, M.; Masterman, G.; “Nahrungsmittel-Intoleranzen: First aid in diagnosis”, Berenkampverlag, 2012;
Drozdowski L, Thomson A.; “Intestinal sugar transport”, World J Gastroenterol 2006 March 21; 12(11):1657-1670
