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There is no difference between suffering from fructose malabsorption and an IBS trigger.
First of all, I really need an empirical definition of fructose malabsorption. I haven't seen a definitive definition of fructose malabsorption in the form of:

A person is considered to suffer from fructose malabsorption if s/he is unable to absorb x grams of fructose ingested over y period of time.

If fructose malabsorption cannot be emprically defined, then perhaps we can think of a it as someone who cannot absorb excess fructose in reasonable amounts. The Skoog-Bharucha 2004 literature review you have repeatedly cited suggests a "reasonable" fructose consumption of 2 servings of excess fructose foods and drinks per meal - including up to 12 ounces of fruit juice or HFCS-sweetened soda as a serving. That's a lot more fructose than is in one little old apple.

Until we have an empirical definition of fructose malabsorption, I'll assume we mean the reasonable consumption definition and go from there.

I agree that fructose will not cause GI symptoms unless your body is unable to absorb it effectively. However, this is not an on/off switch. How well a person absorbs fructose depends on the fructose load as well as on the person's inherent ability to absorb fructose.

My distinction between fructose malabsorption and having IBS has partly to do with the fact that even people who wouldn't be considered to be suffering from fructose malabsorption will, in fact, be unable to absorb fructose if the level ingested is high enough. This is why I avoid HFCS (why add to my fructose load?) and fruit juices (it is, as Heather says, too easy to ingest a lot of fructose very quickly).

There is clinical evidence to show that many IBS suffers are also fructose malabsorbers.
My reading of the literature is that non-IBS suffers also suffer from fructose malabsorption at roughly the same rates. The Skoog-Bharucha 2004 literature review you have cited repeatedly states that "the prevalence of incomplete fructose absorption (25 g. 10%) in healthy subjects is as high as 50%". By contrast the 2003 Choi Iowa paper (I can only find a summary of this) reports 37.5% of the 80 IBS-diagnosed patients tested showed fructose malabsorption.

Furthermore, there seems to be some confusion about whether IBSers who suffer fructose malabsorption are more likely to report symptoms than non-IBSers who suffer similarly. Some studies seems to show they do, but the Skoog-Bharucha 2004 literature review says "The only controlled study that has been performed did not demonstrate a higher prevalence of fructose-induced gastrointestinal symptoms or incomplete fructose absorption in patients with functional gastrointestinal disorders."


One way to determine how much you can handle is to eat something with fructose in it. For example, if you eat a peppermint contain HFCS and it does it give you gas, bloating, cramping and/or D but two mints do then you know roughly how much fructose you can handle.
I have to think that anyone who is scared of apples would fail this test on nerves alone. If someone who is fearful about food eats something and then waits to see if IBS symptoms result, the odds are they will. It's simply a variant of the fact that, for example, I have trouble with my IBS when I'm scared of having trouble with my IBS. The psychological component to IBS makes short-term associations between food and symptoms difficult to determine when the IBSer is waiting anxiously to see if those associations occur.

Personally I think that if you find you cannot handle HFCS then it is quite likely that you should avoid high fructose fruits. If you can handle HFCS then you likely won't have any problems with high fructose fruits.
Apparently there are 2 types of HFCS: HFCS-42 and HFCS-55. HFCS-42 contains less fructose than glucose (presumably 42% to 58%) while HFCS-55 contains more fructose than glucose (presumably 55% to 45%). Even someone with absolutely no ability to absorb excess fructose would tolerate HFCS-42 with no trouble but would, of course, react badly to high fructose fruits. (As I side note, I think these correspond to the European glucose-fructose syrup and fructose-glucose syrup.)

Beyond this, there are suggestions in the literature that it is best to consume fructose with meals and with lactose. So someone who could not tolerate a cola made with HFCS-55 when it is ingested on its own may be fine with an apple provided it is not eaten on an empty stomach.

Furthermore - and this is the point I was making in my earlier post - the fact that someone can tolerate the fructose in HFCS-55 is not a sufficient reason to say, "Oh what the heck, go ahead and eat it." My reading of the literature is that if you make the fructose level high enough, as many as 80% of the healthy subjects tested will demonstrate fructose malabsorption. (I suspect that if you made it higher still you could hit 100%.) In other words, everyone has their own break-even point, beyond which they cannot tolerate excess fructose. Your break-even point is apparently quite low. Mine is apparently quite high. Nonetheless I am sure there is a point at which excess fructose will overwhelm my ability to absorb it. Consuming HFCS would simply add to my fructose load without providing any nutrional benefits and may be the straw needed to push me over my load limit.

The post that started this thread demonstrates this very clearly. The poster had no trouble with applesauce provided he ate the unsweetened kind. Clearly his fructose load limit had not been reached. Once he began consuming applesauce combined with HFCS, however, he began experiencing the classic diarrhea of excess fructose malabsorption. It appears that the HFCS has pushed him past his fructose load limit.

AND of course you can always have a breath test to determine if you are a fructose malabsorber. I don't think the test is commonly available. Usually it is determined by a process of elimination.
It appears to me that hydrogen breath tests to determine fructose malabsorption are not entirely reliable. I also found it interesting to read that not everyone who demonstrates fructose malabsorption experiences symptoms consistent with that condition.

I would think that if someone suspects s/he suffers from fructose malabsorption the simplest course would be to simply eliminate excess fructose for a short period of time - surely a week would be enough - and see if his/her symptoms improve.

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