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Lately there have been some posts from folks who have been having bowel distress even though they have been GF for a long time. I've been looking into this after someone posted a message about how fructose intolerance has many of the same symptoms as celiac. It seems that about 1/3 of the population tests as "intolerant" to fructose, that is, it isn't absorbed well and therefore causes bacterial overgrowth.

However, that didn't seem right to me because sucrose consists of a fructose molecule and a glucose molecule, and you would expect a fructose intolerant person to be just as intolerant of sucrose (table sugar). However, that doesn't seem to be the case for the folks I know. Anyway, I found this:

 
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1439534&dopt=Abstract  
there is no evidence of active intestinal fructose transport in the human intestine. By means of hydrogen breath tests, a very low absorption capacity for fructose given as the free monosaccharide has been found in humans. Fructose given as sucrose or in equimolar combinations with glucose is well absorbed, and only fructose in excess of glucose is malabsorbed. On this basis it is hypothesized that two different uptake mechanisms for fructose are present in the human intestine. One of these may be a disaccharidase-related uptake system. Sorbitol ingestion may aggravate malabsorption of fructose given as the monosaccharide; it is not known whether a specific mechanism is involved. In children and adults with functional bowel distress the absorption capacities for fructose may not differ from those of healthy individuals, but malabsorption of fructose and/or sorbitol may be the cause of or aggravate abdominal symptoms. Fructose polymers (fructans) are also subject to increasing nutritional interest. Fructans are not absorbed in the small intestine but are strongly fermented in the large bowel. Fructans may be of potential benefit for large-bowel function and blood glucose regulation.

Which seems to say that fructose by itself ... read "high fructose corn syrup" really is more of a problem for digestion. More and more products have switched from cane sugar to corn sugar, esp. sodas and candies, so that might be causing a lot of the digestive problems that one might think would be caused by hidden gluten. Fructose malabsorption might not be rare ... it seems to be the norm according to the above article. Beware of soda!

-- Heidi 

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