Fructans are a group of food fibers. As you might guess from the name, fructans are chains of ring-shaped fructose sugars. Humans don't have what it takes to break these chains apart, so the fructose in the chains is not absorbed in the small intestine where other sugars are absorbed. When these dietary fibers reach the large intestine, they are fermented by the bacteria that live there, producing gas. This is no problem for many people, and sometimes fructans are even deliberately added to foods or probiotic supplements for the specific purpose of feeding the "good" bacteria. But for some people with IBS, the gas causes painful bloating.
By far the largest source of fructans in the Western diet is wheat.It accounts for 70% of our fructans intake. The second biggest source is onions, followed by garlic and unripe bananas. You can recognize added fructans in your food or supplements by the names "inulin" or "FOS".
It is important to note that even though wheat happens to be the primary source of fructans in our diets, intolerance of this kind has nothing to do with the wheat protein, gluten, which those with celiac disease must avoid. For a more complete discussion of fructans intolerance versus gluten intolerance, please see my recent guest post on the Kitchen Therapy blog.
Your book doesn't mention ginger. Is ginger just as bad as garlic and onion?
Posted by: Bjean | February 04, 2010 at 11:54 AM
Thats a great example of a food I just dont have any specific information on. If I had to guess, it probably does have fructans in it. To be on the safe side, I would leave it out during the elimination phase of a FODMAPS elimination diet. You can always try it later and see how it goes.
Posted by: Patsy Catsos | February 04, 2010 at 07:19 PM
Thank you for the info, it has given me some greater insight into some of my clients' discomforts. :)
Posted by: Chef Lisa | February 18, 2010 at 02:47 PM