Montalto M, Gallo A, Ojetti V, Gasbarrini A
Institute of Internal Medicine, School of Medicine, Catholic University of the Sacred Heart, Rome, Italy.
Eur Rev Med Pharmacol Sci. 2013;17 Suppl 2:26-9.
Carbohydrate malabsorption is a frequent clinical condition, often associated with abdominal symptoms. Although lactose represents the most commonly malabsorbed sugar, also other carbohydrates, such as fructose, trehalose and sorbitol may be incorrectly absorbed in the small intestine. Fructose malabsorption seems more common in patients with functional bowel disease, even if randomized and controlled studies on these topic were few and on small samples. Interpretation of breath hydrogen testing is difficult. In particular, neither studies comparing this test with a gold standard, nor validated doses and concentrations to be used, are available. Trehalose malabsorption due to trehalase deficiency represents a very rare condition and available studies do not support its relevance in clinical practice. Sorbitol absorption is dose and concentration related, and depends on the entity of intestinal absorption surface. Nevertheless, the finding of its malabsorption is not expression of a specific cause of intestinal bowel damage. From available data, it is not possible to draw definite conclusions about clinical relevance of fructose, trehalose and sorbitol malabsorption, as well as, about diagnostic accuracy of commonly used tests to detect all these conditions. On the other hand, in patients who refer abdominal discomfort after ingestion of different carbohydrate-containing foods, a small intestinal bacterial overgrowth, should be promptly considered. This is because the large amount of intestinal bacteria may unspecifically ferment sugars, causing an abnormal H2 production and consequently a misleading diagnosis of sugar malabsorption.
碳水化合物吸收不良是一种常见的临床病症，常伴有腹部症状。虽然乳糖是最常吸收不良的糖类，但其他碳水化合物，如果糖、海藻糖和山梨醇在小肠中也可能吸收异常。果糖吸收不良在功能性肠病患者中似乎更为常见，尽管关于这些主题的随机对照研究较少且样本量较小。呼气氢试验的解读很困难。特别是，既没有将该试验与金标准进行比较的研究，也没有可供使用的经过验证的剂量和浓度。由于海藻糖酶缺乏导致的海藻糖吸收不良是一种非常罕见的病症，现有研究不支持其在临床实践中的相关性。山梨醇的吸收与剂量和浓度有关，并取决于肠道吸收表面的情况。然而，发现其吸收不良并非肠道损伤的特定原因的表现。根据现有数据，无法就果糖、海藻糖和山梨醇吸收不良的临床相关性以及检测所有这些情况的常用试验的诊断准确性得出明确结论。另一方面，对于摄入不同含碳水化合物食物后出现腹部不适的患者，应及时考虑小肠细菌过度生长。这是因为大量肠道细菌可能非特异性地发酵糖类，导致异常的氢气产生，从而对糖类吸收不良产生误导性诊断。
