In Healthy Eating, Healthy Living by Clara0 Comments


In the article “Fructose malabsorption and hereditary fructose intolerance” we already described how fructose malabsorption is probably  caused by the fact that the GLUT-5 transporter is not working properly. This means that the fructose is not absorbed into the system via the small intestine. It remains in the gut lumen and is transported into the next intestinal section, the large intestine.

Lumen (anatomy)

 In biology, a lumen (from Latin lumen, meaning ‘an opening’; plural lumina) is the inside space of a tubular structure, such as an artery or intestine. The interior of a vessel, such as the central space in an artery or vein through which blood flows.

In the large intestine some bacteria will then metabolize (break down) the fructose into the components hydrogen, CO2 and short-chain fatty acids. The hydrogen will not cause any symptoms, but it can be used for the purpose of diagnosis. Fructose malabsorption can normally be diagnosed with the help of a non-invasive breath test.

It can occur when the ileocecal valve is not closing properly because gas (CO2) is bloating the large intestine. This can cause the stool to flow from the large intestine back into the small intestine (where it shouldn’t be). This in turn causes bacterial imbalance in the intestine, which almost always results in symptoms. This is referred to as “backwash ileitis”.

The ileocecal valve (ileal papilla, ileocaecal valve, Tulp’s valve, Tulpius valve, Bauhin’s valve, ileocecal eminence, valve of Varolius or colic valve) is a sphincter muscle valve that separates the small intestine and the large intestine.

The short-chain fatty acids produce an osmotic gradient and therefore cause the infiltration of fluids into the gut lumen, which leads to runny diarrhoea.

The symptoms of fructose malabsorption thus include

  • bloating
  • flatulence
  • diarrhea or soft stool (often smelly) / constipation
  • nausea
  • stomach ache
  • abdominal cramps

The following secondary symptoms have been observed:

  • Dizziness
  • Reflux
  • Heartburn
  • Tiredness
  • Depressive moods
  • Headache (to the point of migraine)

The intensity of the symptoms depends on the tolerance level of the person and can vary on a day to day basis. On the one day you can be able to tolerate some strawberries and on the next you end up with diarrhea. If you have fructose intolerance you will have to develop a sixth sense for what you can tolerate. You need to gradually figure it out by listening to your body.

Delay of Fructose Intolerance Symptoms

Another hurdle is the delay of symptoms. Some patients report that their symptoms only appear 24-48 hours after the ingestion of fructose.


Leave a Comment