Fructans 101

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.

Comments

[Bjean]

Your book doesn't mention ginger. Is ginger just as bad as garlic and onion?

[Patsy Catsos]

Ginger is fine on the elimination phase of the diet.

Updated 9/11/2011

[Chef Lisa]

Thank you for the info, it has given me some greater insight into some of my clients' discomforts. :)

[Paige]

Hi Patsy, maybe you can answer a question for me. I've been experiencing with wheat-free baking for my toddler daughter who seems very sensitive to fructose/fructans. I don't have any indication that gluten is a problem for her, so I was wondering if wheat gluten itself (packaged as "Vital Wheat Gluten Flour") contains any fructans. In other words, what part of the wheat contains the fructans? If I could add some gluten to give a nice rise to my otherwise wheat-free bread, that would be great!

[Patsy Catsos]

“Vital wheat gluten” is available under several
brands, with small, varying amounts of carbs and fiber listed on the
nutrition information. To be on the safe side, until I learn more about
what
type of carbs/fibers are remaining in vital wheat gluten,
I’d suggest not using
it during the short elimination phase, but it could definitely be useful
for
people later on in the process who want to expand
their
repertoire of wheat-free or low-FODMAPS recipes. Let me know if you come
up
with any good ones! (Obviously this product would never be appropriate
for
anyone with celiac disease or a wheat allergy.)

[Hayley Rutger]

Hi there,

Your book does not forbid chives (at least not anywhere I could see). But if I understand correctly, they have a similar chemical composition to other stuff in that family, like onions.

Advice on whether or not to use chives?

[Patsy Catsos]

The latest nutrient composition data shows that chives (green parts only) do not contain FODMAPs.

Updated 9/11/2011

[Heather Wiggins]

I know that I have trouble with garlic and onions. Does that mean that all fructans are likely 'off limits' for me? Thanks!

[Patsy Catsos]

Not necessarily, but it is a strong clue that this might be a problem area. If one learns through elimination and challenge that fructans are a problem, it may eventually be possible to manage portions so that you can have some foods from this group.

[Heather Wiggins]

Hi Patsy,

I'm on Day 3 of the fructan challenge and experiencing significant symptoms (gas, bloating). These are similar to the symptoms I have when I eat onions/garlic (see above) so are not surprising. Is it safe to assume that fructans are an issue and move on to the next challenge? Or, should I continue with fructans and play around with the amount (or does that happen once I've gone through all of the challenges?)

One last question - should I go back on the elimination diet for a day or two between challenges to clear my system out?

Thanks!!
HW

[Patsy Catsos]

Heres where you say, good to know, then move on to a few days back on the basic elimination diet before doing the next challenge. Youll have the rest of your life to play around with the amounts, as you say. Keep the momentum going!

[Audrey Washburn]

I have a similar question to Paige above and am wondering whether Paige or Patsy made any progress with the "does gluten flour contain fructans" question. I'm trying to figure out if my issue is wheat, gluten, or fructans, and separating them out is a mission. Thanks, Audrey

[Patsy Catsos]

I wrote a post about this you can view at: http://www.ibsfree.net/ibsfree_at_last/2010/03/vital-wheat-gluten.html.

[Patsy Catsos]

Youve identified a tricky subject. On the one hand, the big picture is that you are testing fructans as a group. On the other hand, it doesnt make sense that you would respond identically to any food in the fructrans group because 1) foods vary in how much fructans that contain and 2) quantity counts, and we eat much more of some foods than others. 

The problem with testing the foods one at a time is ignores the big picture and the impact of the total quantity of fructans as a group. But it might be a good second step, if youve identified a problem with the group as a whole.

[Audrey Washburn]

Thanks Patsy! I think the brands of "gluten flour" you mention in your post would be a perfect test for me. I know I'm sensitive to certain fructans and I know I'm sensitive to grains with gluten in them, but I'm still hoping either FODMAP or gluten is the issue, and not both. The brand of gluten flour here in NZ is Healtheries and they have 1.5 g fiber and 2 g sugar for every 100g. I assume this means this brand potentially has both fructans and gluten :(

[Cheryl]

Is freeze dried garlic o.k. on the elimination diet? I am getting ready to start the elimination diet and want to be sure. Thanks.

Your book is fantastic, as are your online updates.

[Patsy Catsos]

I would avoid it on the elimination diet. I think I'll write a post about garlic today, to help everyone with holiday cooking. I'm glad you like the book! Hope the diet helps you.