Fructose malabsorptionE74.1

Widespread metabolic disorder characterized by overload of the enteric fructose-specific GLUT5 transporter (glucose transport proteins). The fructose, which is not absorbed in the small intestine, passes into the colon where it is metabolized by intestinal bacteria to short-chain fatty acids, carbon dioxide, hydrogen and methane. The result is irritable bowel syndrome.

In the rare congenital fructose intolerance (aldolase B deficiency), no fructose is tolerated at all.

H2 fructose breath test.

A distinction is made between fructose malabsorption of food allergies, lactose intolerance and histamine intolerance.

Avoiding foods containing fructose. If consumption nevertheless occurs, the trade offers Fructosin® a medical product for patients with fructose malabsorption. Fructosin contains the enzyme xylose ismerase, which can convert fructose into glucose, and 6.2 g of fructose per capsule.

Consistent dietary therapy (fructose-reduced diet) of the affected persons by a trained ecotrophologist.

According to the current general recommendations "plenty of fresh fruit and wholemeal products" without further details regarding an upper limit, the tolerated upper limit may be exceeded. Between the 1st and 10th year of life this is 1.0-4.0 g of fructose/day. An apple already contains approx. 11.5 g fructose at an average weight of 200 g. About half of the adults cannot absorb more than 25 g of fructose per day. About 50% show clinical symptoms. Foods like honey also contain fructose (see also honey allergy).

1. Velten FW, Bayrl C (2007) Fructose malabsorption - the other side of health-conscious nutrition. Act Dermatol 33: 373-378