Complaints & connections · borters.ch
Malabsorptio fructosae
A question of amount, not an allergy — and sorbitol turns a tolerable portion into an intolerable one.
Also known as: fructose malabsorption · sorbitol · sugar alcohols · sugar-free sweets · apple juice · pear · chewing gum · bloating after fruit
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
Fruit sugar is taken up in the small bowel through a transport route whose capacity is limited in everyone. If more arrives than that route can handle, the rest travels on to the large bowel, where bacteria ferment it: bloating, rumbling, water drawn in. This is neither an allergy nor an enzyme defect but a question of amount — so the answer is almost never “no more fruit” but “how much at once”. Sorbitol, a sugar alcohol, makes it worse twice over: it is absorbed even less well and it additionally blocks the transport route for fruit sugar. That is why apple, pear, dried fruit, sugar-free sweets and chewing gum are the classic triggers — they contain both together. Glucose works the other way: it helps carry fruit sugar along, which is why table sugar is often tolerated better than a glass of juice. Symptoms typically start half an hour to an hour and a half after eating. An important distinction: hereditary fructose intolerance is something entirely different, it shows itself in infancy with the first fruit and belongs in specialist hands.
First juice, dried fruit, apple, pear and everything with sorbitol. If it improves, bring them back step by step — that is the only way to find the limit.
It only measures whether fermentation happens. It counts only if the usual symptoms appear during it — otherwise it is a lab result without a person.
Fruit sugar is absorbed better together with glucose. Berries, banana or sweetened dishes are therefore often better tolerated than plain juice.
The same amount of fruit spread across the day and eaten with a meal often causes no trouble at all.
A permanently narrow range does more harm than good — it impoverishes the diet and weakens the gut flora. After the test phase the amount goes back up.
Any restriction in children should be supervised and time-limited — with the growth chart as the check.
Lightly crush a teaspoon of the seeds, pour over hot water, cover and steep for ten minutes.
Pour hot water over a teaspoon of dried leaves, cover and steep for ten minutes, drink after eating.
There is no drug for it; xylose isomerase in capsule form has been studied on a small scale and is meant to convert fructose in the small bowel. What counts is the amount: about thirty grams of fructose at once overwhelms even a healthy small bowel. Sorbitol worsens the uptake, glucose improves it — which is why an apple is often tolerated less well than a banana. A withdrawal phase lasts two to four weeks, followed by stepwise reintroduction.
About thirty in a hundred people in central Europe absorb fructose incompletely; only some of them have symptoms. The limit lies individually between about ten and twenty-five grams at once — an apple contains around six, a glass of apple juice around fifteen. The breath test takes two to three hours. A withdrawal phase lasts two to four weeks, followed by stepwise reintroduction over six to eight weeks.
The typical window. Distinctly earlier points to the stomach, much later to the large bowel.
The largest portions at once — a glass of juice holds the fruit sugar of several fruits, without their fibre.
A few grams of sorbitol are enough. It is in the small print: sorbitol, xylitol, maltitol, isomalt — everything ending in -ol.
Sorbitol blocks the route by which fruit sugar is taken up. Apple and pear bring both in one bite.
Audible gut sounds, a full belly and loose stools — fever, blood or weight loss are not part of it.
Hereditary fructose intolerance starts in infancy with the first fruit and is a completely different condition.
Fruit and vegetables are the main source — cutting both wholesale costs exactly here.
A check value when the range of foods stays narrow for a long time, especially in growing children.
Soluble fibres like psyllium and oats bind water and make the stool supple. Wheat bran and a lot of raw vegetables, by contrast, increase bloating and pain in a sensitive gut — this distinction explains most of the failures.
Fibre without water makes the stool harder instead of softer. The two belong together, and the effect only sets in after some days.
Draws water into the bowel and therefore works with a sluggish stool. The belly shows the upper limit: if the stool gets too loose, the dose at once was too high.
Yoghurt, kefir, sauerkraut and the like bring living cultures with them. Many tolerate them well; with a strongly bloated belly they can also do the opposite in the first weeks.
Xylose isomerase is offered for fructose intolerance. Two small studies found fewer complaints; the evidence is thin and the product expensive — adjusting the portion size works more reliably.
Effective when deficient; effects on sleep and stress plausible but moderate. Too much causes loose stool.
What is not taken up in the small intestine arrives in the large bowel and ferments there. The fatty acids formed release GLP-1 — which slows the stomach further and deepens the feeling of fullness.
Fructose and tryptophan are partly processed through the same routes in the gut. From this arose the suggestion that fructose malabsorption presses on mood — in humans this is not established.
Most tolerate about 25 g of fructose at once. With glucose more is absorbed, with sorbitol less — which is why an apple often causes trouble and a banana does not.
Sorbitol, mannitol, xylitol and maltitol add up unnoticed; from about 10–20 g a day many get bloating and diarrhoea. One piece of gum holds about 1–2 g.
Here dietary change is the treatment. Most tolerate about 25 g of fructose at once — it is about the portion, not avoidance.
Traditionally used for bloating. Small studies on caraway oil combined with peppermint oil show an effect on cramping pain — they do not remove the cause.