Fructose Malabsorption and IBS

Berries are actually low in fructose and so may provide an option if a fructose malabsorption problem is contributing to your symptoms. Photo: Jonathan Kantor/Getty Images

Is fructose malabsorption part of the IBS puzzle? Some new research has looked at the role that ingesting foods that contain fructose, a type of sugar found in fruits and some vegetables, has on unpleasant digestive symptoms. Although quite limited and preliminary, the initial light that is being shed is certainly worth taking a look at if you suspect that fruits are be contributing to your intestinal distress.

What Is Fructose Malabsorption?

Formerly known as fructose intolerance, fructose malabsorption is a condition in which a person experiences unwanted digestive symptoms after ingesting fructose, the sugar found in many fruits. The condition is thought to be the result of fructose not being fully absorbed in the small intestine. The fructose then makes its way into the large intestine where it is set upon and fermented by intestinal bacteria. This process can effect GI motility and contribute to unwanted gas and bloating. Some people with fructose malabsorption can tolerate small amounts of fructose, but symptoms occur when too much fructose is ingested in too short a period of time. For some individuals, fructose malabsorption may be the result of small intestine bacterial overgrowth (SIBO). The identification of fructose malabsorption is a key component of the theory behind the use of a low FODMAPs diet for IBS.

Fructose malabsorption is a markedly different condition than hereditary fructose intolerance, a genetic disorder typically diagnosed in infancy.

How Is Fructose Malabsorption Diagnosed?

Fructose malabsorption is diagnosed through the use of the hydrogen breath test, which measures the amount of hydrogen in the breath following the ingestion of a fructose solution.

A positive finding for fructose malabsorption would be a rise in breath hydrogen. This increase indicates that the fructose in the solution has been fermented by bacteria in the large intestine.

What are the Research Findings?

One study made a comparison between healthy individuals and people who were self-identified as suffering from fructose intolerance based on the fact that they experienced bloating and flatulence after eating certain fruits. Although the results must be interpreted with caution due to the extremely small number of individuals (8 patients, 4 controls) who participated in the study, the results are interesting. The self-identified patients had higher hydrogen levels and did experience more bloating and flatulence as a result of drinking the solution than did the healthy individuals.

The finding that test subjects experienced symptoms from the fructose solution itself was replicated in another study, one that used a much larger population. A total of 183 individuals who had unexplained digestive symptoms participated.

Three-quarters of these individuals experienced abdominal symptoms following the ingestion of the fructose solution. These symptoms included flatulence, abdominal pain, bloating, belching and a change in bowel habit.

In a slightly different vein, one study looked at the relationship between fructose intolerance and unexplained abdominal pain in children. The study involved giving different doses of the fructose solution to 32 children. Thirteen of the children had a positive hydrogen breath test result. There was an effect of dose size in that the larger the quantity of fructose, the greater the percentage of children who tested positive. Eleven of the children who tested positive were given a fructose-restricted diet to follow. According to the researchers, nine of these children experienced rapid symptom improvement upon following the diet.

One study looked specifically at fructose intolerance in adults diagnosed with IBS. Of the 80 study participants, almost one-third had a positive hydrogen breath test result following ingestion of the fructose solution. Of these patients, 26 participated in a follow-up assessment one year later. On follow-up, 14 of these patients reported that they were able to comply with a fructose-restricted diet and experienced significant improvement in the symptoms of pain, belching, bloating, indigestion and diarrhea.

Difficulty with fructose is one of the key findings behind the low FODMAPs theory for IBS. This theory has received significant research for its effectiveness in reducing IBS symptoms.

The Bottom Line

As you can see, research on the role of fructose malabsorption in IBS is still in its preliminary stages. However, if your symptoms of gas, bloating and diarrhea seem related to the ingestion of fruits, a fructose problem might be something to consider. Keep a food diary for several weeks to determine if there is a such a relationship. If so, speak to your doctor about the possibility of taking the hydrogen breath test and ask your doctor’s opinion about trying an elimination diet.


Choi, Y., Kraft, N., Zimmerman, B., Jackson, M. & Rao, S. Fructose Intolerance in IBS and Utility of Fructose-Restricted Diet. Journal of Clinical Gastroenterology 2008 42:233-238.

Choi, Y., Johlin, F., Summers, R., Jackson, M. & Rao, S. “Fructose intolerance: an under-recognized problem.” American Journal of Gastroenterology 2003 98:1348-1353.

Gomara, R. “Fructose intolerance in children presenting with abdominal pain.Journal of Pediatric Gastroenterology and Nutrition 2008 47:303-308.

Hereditary Fructose Intolerance Medline Plus.

Mann, N. & Cheung, E. “ Fructose-induced breath hydrogen in patients with fruit intolerance.Journal of Clinical Gastroenterology 2008 42:157-159.

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