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.
In the large intestine some bacteria will then metabolise (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 that 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 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 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 diarrhoea. If you have fructose intolerance, then you will have to develop a sixth sense for what you can tolerate by gradually figuring it out and by listening to your body.
Another hurdle is the delay of symptoms. Some patients report that their symptoms only appear 24-48 hours after the ingestion of fructose.
Intestinal Rehabilitation is a method of getting the body "back on track" in order to rehabilitate any possible intestinal bacterial imbalance. Whether the rehabilitation will have to be done with a gentle approach or be "prepared" with the use of antibiotics, is a decision that needs to be made by your medical professional! Regular intestinal rehabilitation or detoxification has resulted in a higher sense of well-being in most of those affected. These rehabilitation programmes should, however, always be done after consulting a medical professional in order to prevent damaging the intestinal system!
Glucose will make it easier for most patients to absorb the fructose in the small intestine. This is however, extremely variable and depends on the availability of different GLUT transporters in your enterocytes! So adding glucose to your meal may help to prevent symptoms.
It is also necessary to factor in how much fructose is being ingested in total per day, because the "glucose-trick" can only make a certain amount of fructose more tolerable. Patient reviews have shown that most patients are able to tolerate some higher levels of fructose together with a combined addition of glucose relatively well.
The consumption of larger amounts of glucose in addition to foods that contain higher levels of fructose is only a temporary solution that you can resort to during your holiday or in a restaurant. It should only be tested out after the fructose-restricted diet!
There is a food supplement produced and developed in Austria, Europe. It is containing the enzyme Xylose Isomerase, which is able to change the fructose into glucose, which can be ingested easily. It should not to be used by diabetics and people suffering from hereditary fructose intolerance (HFI). Link to the producer's online shop (they ship world wide!)
Rainer Klinke, Hans-Christian Pape, Stefan Silbernagl (Hrsg.): "Lehrbuch der Physiologie", 5. Auflage. Thieme, Stuttgart 2005
Thilo Schleip, Fructose-Intoleranz: Wenn Fruchtzucker krank macht, Trias; Auflage: 1 (2005)
M.Ledochowski, "H2 Atemteste", Verlag Ledochowski, 1. Auflage, 2008
Zechmann, M; Masterman, G; "Food Intolerances: Fructose Malabsorption, Lactose and Histamine Intolerance", 2013