one of the pentoses, c5h10o5, a white crystalline sugar, derived from wood.
it is important to see a physician who can measure how well your small intestine is absorbing essential nutrients with tests such as beta-carotene and d-xylose absorption and stool fat concentration. the results can help guide your diet and your need for nutritional supplements. for example, if fat is poorly absorbed, then a low-fat diet and supplements of more easily absorbed fatty acids, like coconut oil or palm kernel oil, may help. while i would agree that protein is important for patients with a low-functioning small bowel, the fiber found in fresh fruits and vegetables can be well tolerated and actually "bulk up" the stools. everydayhealth.com
you will be asked to drink 8 ounces (240 ml) of water that contains 25 grams of a sugar called d-xylose. the amount of d-xylose that comes out in your urine over the next 5 hours will be measured. you may have a blood sample collected at 1 and 3 hours after drinking the liquid. in some cases, the sample may be collected every hour. the amount of urine you produce over a 5-hour period is also checked. your health care provider will tell you how to collect all of the urine during a 5-hour period. medlineplus.gov
often doctors instead do breath tests, such as the 14c-xylose breath test. in this test, the person drinks a liquid containing a special, faintly radioactive marker (carbon-14) attached to a sugar (xylose). if the 14c-xylose is broken down by the excess bacteria, the carbon-14 can be detected in the person’s breath, which suggests the person has bacterial overgrowth. merckmanuals.com