Fructose Intolerance And Lactulose

Dietary fructose intolerance, often referred to as fructose malabsorption, is a condition that is highly prevalent in people with irritable bowel syndrome or other functional gut disorders. When fructose is not absorbed well, it is fermented by the bacteria in the intestines, producing gas that creates abdominal distension. The most common symptoms of fructose malabsorption include bloating, diarrhea, constipation, flatulence, abdominal pain and cramping. Dietary fructose intolerance should not be confused with hereditary fructose intolerance, a serious and rare genetic disorder. Follow your doctor's advice if that is your case.

Lactulose Test

To determine whether you have fructose malabsorption, you will need to have a baseline lactulose breath test. Lactulose is a type of sugar that is not found in food and that cannot be digested in humans. During the lactulose test, a dose of lactulose is given to you and your breath is analysed at different intervals during the two to three hours after. This test is used to determine what type of gas, between hydrogen and methane, is produced by the bacteria in your gastrointestinal tract. Knowing whether your are a hydrogen or methane producer, the lab will be able to measure the right gas on subsequent tests.

Fructose Test

After having done the baseline breath test with lactulose, you will be able to test for fructose malabsorption on a different day. The same procedure used with the lactulose test is used for the fructose test, using fructose instead of lactulose. If your hydrogen or methane levels are high in the hours after you ingest fructose, you will be diagnosed with a fructose malabsorption. People with fructose malabsorption also are often intolerant to fructans, a molecule made of a chain of fructose.

Sorbitol and Lactose Test

If you have a fructose malasorption, it is likely that you have trouble absorbing other types of sugar. Using the same principle used for the lactulose test, a dose of lactose or sorbitol can be given to you and your breath can be analyzed for hydrogen or methane for two to three hours to see at what levels these sugars are fermented in your intestines. Lactose is found in dairy products, especially in milk, yogurt and some fresh cheese, while sorbitol and other polyols are found in plums, prunes, cherries, avocado, mushrooms, cauliflower and sugar-alcohols like sorbitol, xylitol, maltitol and mannitol.

Dietary Fructose Intolerance Diet

If you are diagnosed with a fructose malabsorption following your lactulose and fructose breath test, you will need to make some dietary changes to eliminate your symptoms. A study showing that following a fructose-reduced diet helped to reduce the symptoms in about 75 percent of patients diagnosed with both irritable bowel syndrome and fructose malabsorption was published in 2006 in the "Journal of the American Dietetic Association." To reduce your fructose intake, avoid apples, pears, watermelon, peaches and mango, as well as honey and high-fructose corn syrup. Replace these high-fructose foods with low-fructose alternatives such as blueberry, strawberry, banana, oranges, kiwifruit, maple syrup and regular sugar. Consult a registered dietitian for help determining the best diet for your sugar malabsorption.