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Fructose malabsorption, formerly named "dietary fructose intolerance" (DFI), is a digestive disorder〔(MayoClinic.com )〕 in which absorption of fructose is impaired by deficient fructose carriers in the small intestine's enterocytes. This results in an increased concentration of fructose in the entire intestine. Occurrence in patients identified to be suffering symptoms of irritable bowel syndrome is not higher than occurrence in the normal population. However, due to the similarity in symptoms, patients with fructose malabsorption often fit the profile of those with irritable bowel syndrome. A small proportion of patients with both fructose malabsorption and lactose intolerance also suffer from celiac disease. Fructose malabsorption is not to be confused with hereditary fructose intolerance, a potentially fatal condition in which the liver enzymes that break up fructose are deficient. == Pathophysiology == Fructose is absorbed in the small intestine without help of digestive enzymes. Even in healthy persons, however, only about 25–50 g of fructose per sitting can be properly absorbed. People with fructose malabsorption absorb less than 25 g per sitting.〔http://www.uihealthcare.com/kxic/2008/06/fructose.html〕 In the large intestine, fructose that has not been adequately absorbed reduces the absorption of water osmotically and is metabolized by colonic bacteria into short chain fatty acids, producing the byproduct gases hydrogen, carbon dioxide and methane. This abnormal increase in hydrogen is detectable with the hydrogen breath test. The physiological consequences of fructose malabsorption include increased osmotic load, rapid bacterial fermentation, altered gastrointestinal motility, the formation of mucosal biofilm and altered profile of bacteria. These effects are additive with other short-chain poorly absorbed carbohydrates such as sorbitol. The clinical significance of these events depends upon the response of the bowel to such changes. Some effects of fructose malabsorption are decreased tryptophan, folic acid〔 and zinc in the blood. Restricting dietary intake of free fructose and/or fructans may provide symptom relief in a high proportion of patients with functional gut disorders. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「fructose malabsorption」の詳細全文を読む スポンサード リンク
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