A patient may become intolerant of a fructose load over time. Fructose is normally absorbed in the duodenum. If the person is unable to absorb the fructose then the carbohydrate will pass into the colon where it is converted by the bacteria into gas.


Clinical features:

(1) bloating, abdominal pain, gas and/or diarrhea after a fructose load

(2) history of tolerating fructose-containing beverages or foods in the past

(3) may be relative (able to tolerate small fructose loads, only becoming symptomatic with a high load)

(4) may exclude sources of fructose from the diet


The diagnosis can be suspected if the problematic symptoms improve on avoidance of fructose. Avoidance of fructose can be challenging since it is present in so many foods.


A breath test can confirm the diagnosis.


Differential diagnosis:

(1) hereditary fructose intolerance

(2) irritable bowel syndrome

(3) lactose intolerance (may co-exist with fructose intolerance)

(4) other carbohydrate intolerance


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