When we eat fruit, fructose (the sugar found in fruit) passes through the walls of the small intestine lining into the bloodstream. Once in the blood, it is converted into glucose which the body utilises to burn for energy. For the fructose to pass through the small intestine lining there is a mechanism (called transport mechanism) and if this is defective fructose is not absorbed and reaches the colon. This results mainly in two complaints:

  1. Water accumulates through osmosis in the small intestine causing diarrhoea because this surplus liquid cannot be absorbed in the colon.
  2. Fructose is decomposed in the colon by bacteria forming short-chain fatty acids and gases, and this causes complaints such as flatulence, bloating, abdominal pain and headache.

Fructose malabsorption can be diagnosed simply and painlessly by the Hydrogen Breath Test (HBT), one of the ranges of investigation carried out by the Paediatric Gut Investigation Clinic.

Fructose Malabsorption must not be confused with Fructose Intolerance or Hereditary Fructose Intolerance (HFI), the genetic condition which lacks the enzyme that breaks down fructose in the liver. HFI is usually diagnosed at a young age when babies start to eat food or have a formula containing fructose.

HFI can cause serious liver problems if left unmanaged. Fortunately, like fructose malabsorption, it can be effectively managed with diet changes.

For more information, please contact the clinical team at the Paediatric Gut Investigation Clinic.


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