Fructose intolerance is common in irritable bowel syndrome, or IBS, but avoiding foods that contain this simple sugar could have adverse effects on your health. Fructose occurs naturally in many fruits and is used to sweeten foods or beverages. By combining fructose with glucose, you may be able to digest fructose more efficiently and enjoy the nutritional benefits of fructose-containing foods. Sucrose, a refined sugar that combines fructose and glucose, is absorbed more efficiently than free fructose and may enhance absorption of fructose-rich foods.
Sources
Sucrose is a refined sugar used in syrups, candy, sweetened cereals, condiments and many other foods. Fructose occurs in foods in three forms: as the free fructose found in fruit or honey; as a component of a double sugar, such as sucrose; or as fructan. Fructan is a form of fructose found in wheat and some vegetables. Breads, cereals, pasta or other foods made with wheat may trigger abdominal cramps and gas in people with IBS.
Significance
If you have IBS, finding alternatives to the foods that trigger bowel spasms, diarrhea, gas and cramping can be challenging. Fructose, a single-molecule sugar that many people with IBS can't absorb, is widely consumed in fruits, vegetables and wheat products. Instead of eliminating fructose from your diet, nutritionists are developing ways to improve its absorption through dietary management. Although you may be able to digest sucrose more easily, foods high in refined sugar may add few nutrients to your diet and could cause unwanted weight gain.
Structure
Sugars vary according to the number of molecules they contain in their basic chemical structure. Fructose, found in fruits and some sweeteners, is a simple sugar and contains one molecule. Sucrose, which you know as table sugar, is a double sugar that combines a fructose molecule with a glucose molecule in its basic structure.
Malabsorption
People with IBS are more likely to have difficulty digesting fructose than sucrose. Because of its simple structure, fructose empties more rapidly from your stomach than sucrose. If your small intestine does not absorb enough fructose --- a common complication in people with IBS --- the remaining fructose passes straight to the colon, where bacteria quickly break it down. This fermentation of fructose in the colon can trigger muscle spasms, bloating and gas. Because sucrose has a more complex structure than fructose, sucrose is absorbed more effectively in the small intestine and is not as likely to provoke IBS symptoms.
Management
Susan J. Shepherd, master of nutrition and dietetics, and Peter R. Gibson, M.D., developed a diet to manage fructose intolerance in people with IBS. The diet limits or eliminates foods with high amounts of free fructose, such as some fruits, honey and foods containing high-fructose corn syrup. Foods that combine glucose and fructose in balanced quantities are encouraged. Many fruits, including peaches and apricots, berries, citrus fruits, and bananas, have equal amounts of fructose and glucose, or greater amounts of glucose than fructose. People with IBS who followed this diet closely reported a significant improvement in symptoms after 14 months. To maximize caloric intake, Shepherd and Gibson recommend focusing on nutrient-dense fruits that provide a combination of fructose and glucose, while eating only moderate amounts of sucrose.
