Fructans are the fraction of wheat, onion and chicory fibre that ferments hard and leaves some people bloated, and the standard answer is to avoid the foods that carry them.
Fructanase is an enzyme that breaks fructans down to fructose in the laboratory. The authors wanted to know whether taking it alongside a fructan load does the same thing inside a person, ahead of the colon, and whether that shows up as fewer symptoms rather than only as different chemistry.
Drawn from the paper's stated objective.
Each participant ate 25 g of inulin stirred into 40 g of oatmeal on two occasions, once with a fructanase capsule and once with a maltodextrin placebo, rating symptoms for 24 hours and giving breath samples hourly for 8 hours.
The headline 0 to 8 hour overall abdominal symptom score did not separate the two conditions (p=0.13). Within that window, abdominal pain (p=0.044), fatigue (p<0.001) and burping (p=0.040) did.
The clearer separation came later. Across 8 to 24 hours the overall abdominal symptom score favoured the enzyme (p=0.030), along with bloating (p=0.011), abdominal pain (p=0.019) and flatulence (p=0.044).
Breath hydrogen and methane showed no significant difference between conditions at any point, which is the measurement the mechanism depends on.
| Overall abdominal symptoms, 0 to 8 h | no difference, p=0.13 |
| Overall abdominal symptoms, 8 to 24 h | favoured enzyme, p=0.030 |
| Bloating, 8 to 24 h | p=0.011 |
| Flatulence, 8 to 24 h | p=0.044 |
| Breath hydrogen and methane | no significant difference |
Open question The authors do not claim to know why.
The stated premise is straightforward. Fructanase hydrolyses fructans to fructose in a test tube, so taking it with inulin should mean less fructan arriving in the colon and less fermentation.
The study's own data undercut that account. Breath hydrogen and methane are the standard non invasive readout of colonic fermentation, and neither differed between conditions.
So the symptom benefit, such as it is, is not explained by reduced fermentation on the evidence presented here.
The authors offer no alternative account we can point to, so the honest answer is that the reason for the symptom benefit is unsettled.
Drawn from Abstract and the study's own breath gas data, full text behind a publisher block.
There is now a symptom signal for a fructan digesting enzyme, and simultaneously a reason to doubt the mechanism everyone assumed it worked by. The finding and its explanation moved in opposite directions.
Thirty healthy adults in their late thirties given a single large inulin load, not people with IBS or diagnosed fructan intolerance.
The authors name it themselves: the same trial in people with IBS or fructan intolerance, ideally run by a group with no commercial interest in the enzyme, with a primary endpoint chosen in advance.
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