In fructose malabsorption, the absorption of fruit sugar (fructose) into the cells of the small intestine is reduced, which leads to complaints such as flatulence, diarrhoea, etc. The diagnosis can be established with a hydrogen (H2) breath test. It is not known how many people are affected by fructose malabsorption.
In fructose malabsorption, functioning of the transport protein for fructose is impaired. As a result, fructose cannot be adequately absorbed into the intestinal cells.
Fructose is naturally present in pip and stone fruits (including dried or as juice) as well as honey. Substantial quantities of fructose are often added to lifestyle products (e.g. low-calorie soft drinks or milk products) or specialist products for diabetics. Furthermore, the absorption of fructose is reduced by sugar alcohols. These include:
- Sorbitol (E420)
- Mannitol (E421)
- Xylitol (E967)
- Maltitol (E965)
- Lactitol (E966)
- Isomalt (E953)
From the medical point of view, fructose malabsorption does not have any serious consequences, but it can be very stressful for sufferers.
Fructose malabsorption must be differentiated from the rare condition of hereditary fructose intolerance, which is an inherited disorder of fructose metabolism that is usually diagnosed in infancy. Sufferers must strictly avoid foods containing fructose.
The fructose not absorbed in the small intestine is converted to short-chain fatty acids by bacteria in the large intestine, which can cause the following typical symptoms: stomach pains through to stomach cramps, flatulence, diarrhoea, constipation, feeling of pressure in the upper abdomen, nausea, general malaise, vomiting and belching.
Fructose malabsorption is diagnosed by means of a hydrogen (H2) breath test. The dietary history and, where appropriate, a food and symptom diary may provide evidence of individual tolerance of fructose and the influence of sugar alcohols.
Treatment / Therapy
For a maximum of two weeks after the diagnosis has been made, sufferers should eat a low-fructose diet and omit sugar alcohols (elimination phase). Then individual tolerance of fructose is determined in a test phase. This involves gradually increasing the amount of food containing fructose that is consumed. Finally, individual dietary recommendations are put together.
As a rule, fructose is absorbed more effectively if foods rich in fats or protein are eaten at the same time. Fructose can also be better absorbed when combined with glucose.
Example: Strawberries combined with cream and sugar or a strawberry tart are generally tolerated better by sufferers than strawberries on their own.
Editors: aha! Swiss Allergy Centre in cooperation with the scientific advisory board.
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