Fructose and Fructan Malabsorption in IBS


Fructose and Fructan Malabsorption: Challenges and Considerations in Dietary Management

Fructose and fructan malabsorption are significant dietary concerns, particularly for individuals suffering from Irritable Bowel Syndrome (IBS). These conditions arise when fructose or fructans, which are types of carbohydrates, are not effectively absorbed in the small intestine. As a result, these unabsorbed carbohydrates ferment in the colon, leading to the production of hydrogen and methane gases, which can cause a range of uncomfortable symptoms including bloating, gas, and diarrhea.

Understanding Fructose and Fructan Malabsorption

Fructose is a monosaccharide found naturally in fruits, honey, and commonly added to processed foods in the form of high-fructose corn syrup. Fructans, on the other hand, are polymers of fructose and are prevalent in foods like wheat, onions, and garlic. Although both are categorized under FODMAPs (Fermentable Oligo-, Di-, Monosaccharides, and Polyols), they can cause similar gastrointestinal symptoms when malabsorbed.

The degree of malabsorption varies among individuals and is influenced by several factors, including the amount of fructose or fructans ingested and the overall health of the gastrointestinal tract. Typically, symptoms are more pronounced in individuals with IBS, as their guts are more sensitive to the effects of malabsorption.

Dietary Adjustments for Managing Symptoms

Identifying fructose and fructan malabsorption can significantly improve symptom management. A low FODMAP diet, which involves limiting foods high in fermentable carbohydrates, has been shown to reduce symptoms in many patients. However, the approach to managing these dietary triggers must be personalized, as individuals can vary in which FODMAPs they are sensitive to and to what extent.

For instance, small amounts of fructose might be well-tolerated by some, while others might react to even minimal amounts. Similarly, certain foods containing fructans might trigger symptoms in some but not others. This makes it crucial for dietary management plans to be tailored to the individual’s specific tolerances, which can often be determined through trial and error under the guidance of a dietitian.

The Role of Diagnostic Tests

Hydrogen and methane breath tests are commonly used to diagnose fructose and fructan malabsorption. These tests measure the levels of hydrogen and methane in the breath after the ingestion of a fructose or fructan solution. A significant rise in these gases indicates that malabsorption is occurring. While these tests are invaluable for confirming malabsorption, they are just one tool in managing dietary triggers.

Future Perspectives

Despite the challenges posed by fructose and fructan malabsorption, ongoing research continues to shed light on the complexities of these conditions. Understanding the physiological basis for why some individuals malabsorb these carbohydrates while others do not could lead to more effective treatments and dietary recommendations.

In conclusion, fructose and fructan malabsorption present significant challenges for individuals, particularly those with IBS. Through careful dietary management and the use of diagnostic tests, it is possible to mitigate the symptoms associated with these conditions. Tailoring diets to meet the specific needs of individuals based on their tolerance levels remains a cornerstone of effective management. As research advances, new insights will hopefully provide more refined strategies for dealing with these common dietary issues.


  1. Sia T, Tanaka RO, Mousad A, et al. Fructose malabsorption and fructan malabsorption are associated in patients with irritable bowel syndrome. BMC Gastroenterol 2024 Apr 24;24:143.
Last update: 2 May 2024, 10:32


Gastroenterologist - Hepatologist, Thessaloniki

PhD at Medical School, Aristotle University of Thessaloniki, Greece

PGDip at Universitair Medisch Centrum Utrecht, The Netherlands

Ex President, Hellenic H. pylori & Microbiota Study Group