Fructose, also known as fruit sugar, is absorbed and metabolized differently than the other main type of sugar, glucose. Starches are made of glucose, but table sugar is made of equal amounts of fructose and glucose. Other sweeteners, fruits and vegetables also contain varying amounts of fructose. Some people can experience bloating and gastrointestinal problems when they eat too much fructose.
Fructose in the Diet
All fruits contain fructose, and the sugars glucose and sucrose. All are present in varying proportions, depending on the fruit. Pears, watermelon, mangoes, apples, dried fruits and fruit juices have higher fructose levels. In some sweeteners, such as high-fructose corn syrup, honey and agave syrup, more than half the sugars are in the form of fructose. Any foods containing fruits or added sweeteners -- including yogurt, soft drinks, candies, cookies and baked goods -- are likely to constitute a significant source of fructose in your diet and may cause some bloating.
Malabsorption
Fructose is absorbed through a different facilitative transporter, called GLUT5, than glucose. Some people do not have enough GLUT5 transporters or their transporters are not as efficient. This problem is called fructose malabsorption, and it can be diagnosed with a hydrogen breath test. If you experience bloating after eating foods high in fructose, it is possible that you have fructose malabsorption. Ask your doctor to be referred for a hydrogen breath test to help diagnose the problem.
Bloating
The bloating associated with fructose malabsorption comes from the fermentation of unabsorbed fructose in your intestines. If you don't absorb the fructose, the bacteria living in your digestive tract will eat this fructose, and the large amount of gas produced can cause bloating. Unabsorbed fructose can also cause water retention in your intestines, which can also worsen your bloating.
Low-Fructose Foods
If the fructose in some foods causes you to feel bloated, replace these foods with low-fructose foods. Most nonstarchy vegetables have a low fructose content, with the exception of sugar snap peas, artichoke and asparagus. Meats, eggs, poultry, cheese, olive oil, butter, coconut oil and nuts are also low in fructose. You can consume small amounts of low-fructose fruits, such as berries, banana and citrus fruits, without worrying about getting bloated, as long as you limit yourself to one serving at a time. Avoid sweeteners or sweetened foods or beverages to keep your fructose intake low.
References
- "Journal of Gastroenterology & Hepatology"; Evidence-Based Dietary Management of Functional Gastrointestinal Symptoms: The FODMAP Approach; Peter R. Gibson; October 2009
- "IBS--Free at Last!: A Revolutionary, New Step-by-Step Method for Those Who Have Tried Everything. Control IBS Symptoms by Limiting FODMAPS Carbohydrates in Your Diet"; Patsy Catsos; 2009
- USDA National Nutrient Database: Nutrient Data Laboratory
