Alternative for fructose intolerance - avoiding fruity foods when road cycling

Question from Matthias K.: I am 44 years old and drive less than 4,000 kilometres a year on average. A gastroenterologist has now diagnosed me with fructose intolerance. The breath test showed a value of 78, which is rather high. As I like to drink fruit juice spritzers and fruit bars when cycling, this has tended to increase my symptoms (abdominal pain, flatulence). Do you have any tips for me on what I could eat when I'm travelling?

Answer from nutritionist Uwe Schröder: If fruit sugar (= fructose) is poorly tolerated, this is usually due to intestinal fructose intolerance, also known as fructose malabsorption (poor absorption by the intestinal wall). In this case, the undigested fructose reaches deeper sections of the intestine (large intestine). This can lead to flatulence and diarrhoea due to water retention and bacterial degradation. In contrast, heriditary fructose intolerance is a serious metabolic disorder that already occurs in infants. In contrast, in the milder form, fructose does not have to be completely avoided. Many people can tolerate varying amounts of fructose as long as they are not doing sport - especially if they consume fructose at the same time as other sugars such as glucose. Most people can therefore also tolerate household sugar, which consists of half fructose and half glucose.

As fructose is found in fruit, some vegetables and honey, you should look for foods with a low fructose content (e.g. apricot, papaya, peach) or avoid these foods before exercising. If you consume foods containing fructose in the gramme range during sport, the symptoms can accelerate and intensify. If you exercise for a longer period of time, the blood is shifted to the periphery of the body to support the working muscles, so that the intestines are also supplied with less blood. This is why the longer you exercise, the less well you can tolerate all foods. Bars with dried fruit, fruit bars and apple juice spritzer therefore have a particularly negative effect on existing malabsorption.

You should therefore avoid fruit bars and juices when exercising and instead eat cereal bars or fructose-free gel. There are also sports drinks without fructose. If you absolutely have to have apple spritzer, an extra 5 grams (1 teaspoon) of household sugar is often enough, or better still 5 grams of glucose (dextrose) and a pinch of salt per 100 millilitres. Maltodextrin is better as it consists only of glucose chains. The chain length is indicated by the number on the label: the higher the number, the shorter the glucose units (from 6 to 19). The shorter the chain (MD 19), the stronger the osmotic effect and the greater the risk of diarrhoea. Advice: one litre of mineral water with a mixture of 40 to a maximum of 80 grams of maltodextrin with MD 6 to 12, plus one gram of table salt. You should tolerate this mixture well.