Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0000737 (abdominal pain)
 31,184 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fructose is a hexose sugar that is being increasingly consumed in its monosaccharide form. Patients who exhibit fructose malabsorption can present with gastrointestinal symptoms that include chronic diarrhea and abdominal pain. However, with no clearly established gastrointestinal mechanism for fructose malabsorption, patient analysis by the proxy of a breath hydrogen test (BHT) is controversial. The major transporter for fructose in intestinal epithelial cells is thought to be the facilitative transporter GLUT5. Consistent with a facilitative transport system, we show here by analysis of past studies on healthy adults that there is a significant relationship between fructose malabsorption and fructose dose (r = 0.86, P < 0.001). Thus there is a dose-dependent and limited absorption capacity even in healthy individuals. Changes in fructose malabsorption with age have been observed in human infants, and this may parallel the developmental regulation of GLUT5 expression. Moreover, a GLUT5 knockout mouse has displayed the hallmarks associated with profound fructose malabsorption. Fructose malabsorption appears to be partially modulated by the amount of glucose ingested. Although solvent drag and passive diffusion have been proposed to explain the effect of glucose on fructose malabsorption, this could possibly be a result of the facilitative transporter GLUT2. GLUT5 and GLUT2 mRNA have been shown to be rapidly upregulated by the presence of fructose and GLUT2 mRNA is also upregulated by glucose, but in humans the distribution and role of GLUT2 in the brush border membrane are yet to be definitively decided. Understanding the relative roles of these transporters in humans will be crucial for establishing a mechanistic basis for fructose malabsorption in gastrointestinal patients.
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PMID:Intestinal fructose transport and malabsorption in humans. 2114 1

Fructose malabsorption came to prominence in the pediatric arena as so-called "apple juice diarrhea," with excess consumption of fructose being linked to gastrointestinal symptoms such as diarrhea and abdominal pain. Over the past two decades the amount of fructose in children's diets has been increasing in the United States. A test for fructose malabsorption has yet to be fully validated, due mainly to the lack of an established etiology. In animal models, however, the fructose transporter GLUT5 is developmentally regulated, and this could be consistent with the greater susceptibility of children, especially toddlers, to fructose malabsorption. Additionally, the available evidence indicates the fructose breath hydrogen test has no apparent diagnostic utility in infants younger than 1 year; it may, therefore, be advisable to test for malabsorption by dietary exclusion in these patients. The present review aims to expound on the biological basis for fructose malabsorption in children and evaluate the current evidence for diagnostic procedures in order to identify clinical testing strategies that can be recommended and areas where further investigation is required.
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PMID:Developmental changes and fructose absorption in children: effect on malabsorption testing and dietary management. 2359 Jul 6