If you believe you have a sensitivity to fructose, also called fructose malabsorption, you may have noticed that some foods trigger unpleasant symptoms. The most commonly experienced symptoms include abdominal distension, pain, cramping, flatulence, diarrhea and constipation. Fructose malabsorption appears to be fairly common in people suffering from functional gut disorders, such as irritable bowel syndrome, and can be managed by following a fructose-reduced diet.
Mechanisms
Fructose, a sugar naturally occurring in fruits and also found in some sweeteners, is usually absorbed in the small intestines. However, if you have fructose malabsorption, the unabsorbed fructose sits in your intestines where it attracts large volume of water, resulting in diarrhea. Fructose can also cause problems by being fermented by the bacteria present in your colon, producing gas and making you feel bloated.
Diagnosis
Fructose malabsorption can be diagnosed with a breath test. You will first need to do a lactulose test, a baseline test that is required to assess whether you produce more hydrogen or more methane when not absorbing fermentable sugar properly. On a separate day, you will be given a dose of fructose and your breath will be tested every 20 to 30 minutes over the course of two to three hours for levels of methane or hydrogen. High levels of either methane or hydrogen indicate a diagnosis of fructose malabsorption.
Limiting Fructose
You can control your symptoms by adhering to a fructose-reduced diet. Avoid foods that contain more fructose than glucose or that contain too much fructose per serving. Stay away from pears, apples, watermelon, honey, agave syrup and high-fructose corn syrup because they contain more fructose than glucose. Fruit juices, dried fruits and large servings of sugar or desserts should also be avoided because of the high amount of fructose they contain. Instead, choose safer fruit alternatives, such as banana, blueberry, strawberry, kiwifruits and oranges and sweeteners like regular or raw sugar and maple syrup.
Other Problematic Fermentable Carbohydrates
Many people diagnosed with fructose malabsorption also experience symptoms when eating foods containing high amounts of short-chain fermentable carbohdyrates, which include lactose, fructans, galactans, oligosaccharides, sorbitol, mannitol and other sugar-alcohols. Lactose are mainly found in milk, yogurt and soft cheese, while fructans are present in onions, leeks and garlic. Legumes, including beans, lentils and soy products, are rich in galactans, while sorbitol and mannitol are found in cherries, sweet potato, cauliflower, avocado and mushrooms. Sugar-alcohols are often added to sugar-free foods. For help determining which foods you should avoid or include in your diet, consult a registered dietitian with specialization in this area.
References
- Shepherd Works: Hydrogen Breath Testing
- "Journal of the American Dietetic Association"; Fructose Malabsorption and Symptoms of Irritable Bowel Syndrome: Guidelines for Effective Dietary Management; Susan J. Shepherd and Peter R. Gibson; 2006
- "Practical Gastroenterology"; Clinical Ramifications of Malabsorption of Fructose and Other Short-chain Carbohydrates; Jacqueline S. Barrett and Peter R. Gibson; August 2007
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