ABOUT THE TEST The test consists of administering a solution of fructose and sorbitol orally and collecting the expired air at different times. (each 30 minutes), to determine the amount of hydrogen and/or methane exhaled through the breath. The total duration of the test is 3 hours and a half (210 minutes). Under normal conditions, fructose and sorbitol are absorbed in the small intestine.. If there is insufficient absorption of any of these sugars due to a deficiency in their intestinal transporters, These reach the large intestine where they are fermented by resident bacteria., producing gases (hydrogen and/or methane) which are partially absorbed by the blood and expelled through the breath. Thus, according to the results obtained of hydrogen and/or methane exhaled for each intake, we can detect a possible intolerance to fructose and/or sorbitol. To interpret the results you should go to a specialist who knows your clinical situation., This being essential in the event that any of the results are positive.