Nowadays, the range of fruit is larger and more varied than ever. But not everyone can enjoy fruit without restrictions. Are you also one of those people who often experience a rumbling in the stomach after eating fruit? Then you may have fructose malabsorption or intestinal fructose intolerance.
Test for fructose intolerance
It is not known exactly how many people in Germany suffer from fructose malabsorption or fructose intolerance. Many seem to be affected without a diagnosis. This is quite simple with the help of a test, the so-called “H2 breath test” or fructose hydrogen breath test: This fructose malabsorption test measures whether the typical intestinal gases are produced and exhaled after exposure to fructose via the breath. If the typical symptoms also occur when the test is performed, fructose intolerance can be assumed.
Fructose malabsorption: what are the causes?
In fructose malabsorption, the absorption of fructose, i.e. fruit sugar that occurs in fruit and honey, for example, is disturbed in the small intestine. Normally, a transporter transports the sugar component fructose from the food into the cells of the small intestine and thus into the bloodstream. In fructose malabsorption, this transport system is defective or its performance is impaired. Large amounts of fructose therefore reach the large intestine undigested. The bacteria present there break down fructose into short-chain fatty acids and gases such as hydrogen or carbon dioxide, which can trigger the symptoms.
Fructose malabsorption or intestinal fructose intolerance?
Although the two terms are often used interchangeably, there is a difference between fructose intolerance and fructose malabsorption. From a medical perspective, the following definition applies:
- Malabsorption occurs when fructose is not properly absorbed in the small intestine and therefore large portions of it end up in the large intestine.
- Intestinal fructose intolerance is when the fructose is actually intolerant and malabsorption of fructose leads to discomfort.
Delineate hereditary fructose intolerance.
Fructose malabsorption should also not be confused with congenital (hereditary) fructose intolerance. This is a rare disorder of fructose metabolism in which affected individuals lack an enzyme needed to break down fructose. It requires strict avoidance of fructose from birth.
Symptoms of fructose intolerance
Typical signs of fructose intolerance usually include a combination of some of the following symptoms:
- Abdominal pain or cramping
- Visibly distended abdomen
- (malodorous) flatulence
- Diarrhea or constipation
- Bad breath
- Difficulty concentrating, fatigue or headaches
- Nausea
- Heartburn
If those affected avoid fructose, the symptoms disappear completely. However, a complete renunciation of fructose does not have to be even with fructose intolerance, because a small amount of fructose is usually tolerated. Fructose tolerance varies from person to person and must be determined individually. In some people, the symptoms of intolerance are only temporary; in others, fructose can cause problems throughout life.
Fructose intolerance – what to do?
After a diagnosis of fructose intolerance, a period of abstinence is usually recommended first, during which fructose is completely avoided. After that, fructose-containing foods can (and should) be gradually reintegrated into the diet and one’s own limits tested. In the course of time, when the intestine has recovered further, these limits can be shifted further and further. A doctor or nutritionist can help create an individualized diet plan to avoid becoming malnourished. Common consequences of fructose intolerance are a deficiency of zinc or folic acid, so that – after consultation with the attending physician – a supply via dietary supplements can be useful.
Nutrition: which foods to avoid?
The simple sugar fructose is a natural component of fruit and numerous vegetables. Foods particularly high in fructose include:
- Apples
- Pears
- Plums
- Grapes
- Dates
- Tomatoes
Fructose is also found in fruit juice, fruit yogurt, cereal bars, dried fruit, jam, confectionery and soda and cola. Fructose is also often added to foods such as bread or sausage. Caution also applies to alcohol: especially sweet drinks such as sweet wine or liqueur contain a lot of fructose. Therefore, it is important for fructose intolerance sufferers to read the list of ingredients carefully when shopping. However, caution is advised with the labeling “fructose-free” or “without fructose”: This often just means that no additional fructose has been added. Nevertheless, fructose may be present in these foods.
What to eat if you are fructose intolerant?
A fructose intolerance means only in the fewest cases a complete renunciation of east and vegetables. On the contrary, a complete renunciation can lead to vitamin deficiencies and is therefore not advisable. The goal should therefore not be to eat fructose-free, but low-fructose foods. Comparatively well tolerated foods in fructose intolerance are for example:
- Zucchini
- Eggplant
- Lettuce
- Cucumber
- Chicory
- Mushrooms
- Celery
- Apricot
- Papaya
- Honeydew melon
These factors influence the tolerance
Individual tolerance of fructose may also depend on:
- The type of preparation
- The combination of different foods in one meal
- The total amount of fructose ingested that day
The time of day or the timing of the meal can also play a role. So fructose is usually better tolerated directly after a main meal and in the afternoon. Special recipes as well as tables with information on the fructose content of foods can be found on the Internet and can make low-fructose cooking easier for those affected. It may be advisable to keep a list yourself of which foods are usually well tolerated.
Sugar in intestinal fructose intolerance
The sugar substitute sorbitol should also be avoided in fructose intolerance. Because sorbitol uses the same means of transport in the intestine, it can decrease the absorption of fructose in the short term. Sorbitol is found in some types of fruit and is added to many products – just like fructose – as a sugar substitute. Glucose (dextrose), on the other hand, favors fructose absorption because it stimulates the activity of the transporter. For this reason, sucrose (household sugar), which consists of half fructose and half glucose, is better absorbed by some sufferers. In the case of fructose intolerance, it can also be helpful to add glucose now and then when cooking fruit or vegetables in order to increase the digestibility of a dish. Stevia or rice syrup are also suitable for sweetening – agave syrup, honey or maple syrup, on the other hand, are not suitable. Milk sugar (lactose) can also be an alternative in the case of fructose intolerance, provided that one is not also affected by lactose intolerance.
