Irritable Bowel Syndrome Message Boards

Glad to hear you are feeling better.

It is a common misconception that fructose malabsorption occurs only in IBS-D. A recent clinical study up to 50% of IBS-C and IBS-D have fructose malabsorption (See reference below). I have replicated the table from the study in this posting and provided a detailed explanation in these two postings ( posting 1 and posting 2 )

While normal individuals can absorb 25 to 60 grams or so of excess fructose in the small intesting an individual with fructose malabsorption may only be able to absorb a few grams. I have fructose malabsorption and I can only handle a couple of grams of excess fructose. A small apple or pear contains about 5 grams of excess fructose and a tablespoon of honey can contain 3 grams. So individuals with fructose issues have to be careful so as not to trigger IBS symptoms from some common foods with excess fructose.

One way it is thought that fructose malabsorption affects individuals with IBS-C is that the excess fructose that is not absorbed reaches the colon where it acts like fast food for the colonic bacteria. During the fermentation process fructose is converted to byproducts and gases such as carbon dioxide, hydrogen and methane. Over the past decade it has been found that as the concentration of methane in the colon increases the degree of constipation increases. There are suggestions now that this characteristic might be used as a bio-marker to distinguish IBS-C from other subtypes (see reference below).

There is a link in my signature to an excellent detailed discussion on fructose malabsorption and IBS along with some dietary guidelines.

Reference
BARRETT, J. S., IRVING, P. M., SHEPHERD, S. J., MUIR, J. G., & GIBSON, P. R. (2009). Comparison of the prevalence of fructose and lactose malabsorption across chronic intestinal disorders . Alimentary Pharmacology & Therapeutics, 30(2), 165-174

Hwang, L., Low, K., Khoshini, R., Melmed, G., Sahakian, A., Makhani, M., et al. (2010). Evaluating Breath Methane as a Diagnostic Test for Constipation-Predominant IBS . Digestive Diseases and Sciences, 55(2), 398-403

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STABLE: ♂, IBS-D 50+ years - Science of IBS

The FODMAP Approach to Managing IBS Symptoms
Evidence-based Dietary Management of Functional GI Symptoms: The FODMAP Approach
FODMAP Chart & Cheatsheet
The Role of Food & Dietary Intervention in IBS

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