Xylose absorption in Down's syndrome.

A standard xylose absorption test was carried out in 14 people with Down's syndrome (DS) and in 14 age-matched mentally deficient controls; a further 30 people with DS were similarly investigated. Mentally deficient people as a group were found to have impaired xylose absorption, the matched DS subjects having a significantly reduced xylose absorption (P less than 0.001) when compared to the mentally deficient controls. Ninety percent of the DS subjects had a xylose excretion below the normal range. At present it is not possible to identify the cause of the malabsorption but it is highly likely that the malabsorption plays a role in a number of the vitamin and mineral deficiencies found in people with DS.