Fructose Malabsorption is Associated with Decreased Plasma Tryptophan

Abstract

Background: Fructose malabsorption is characterized by the inability to absorb fructose efficiently. As a consequence fructose reaches the colon where it is broken down by bacteria to short fatty acids, CO₂, H₂, CH₄ and lactic acid. Bloating, cramps, osmotic diarrhea and other symptoms of irritable bowel syndrome are the consequence and can be seen in about 50% of fructose malabsorbers. Recently it was found that fructose malabsorption was associated with early signs of depressive disorders. Therefore, it was investigated whether fructose malabsorption is associated with abnormal tryptophan metabolism. Methods: Fifty adults (16 men, 34 women) with gastrointestinal discomfort were analyzed by measuring breath hydrogen concentrations after an oral dose of 50 g fructose after an overnight fast. They were classified as normals or fructose malabsorbers according to their breath H₂ concentrations. All patients filled out a Beck depression inventory questionnaire. Blood samples were taken for plasma tryptophan and kynurenine measurements. Results:

• Fructose Loading Test Fructose Malabsorption H2 Exhalation Tryptophan