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Reproducibility of the breath hydrogen measurement after a low and high fibre meal.

OBJECTIVE
To assess the intra-subject variability of the breath hydrogen (H2) response to a low and a high fibre test meal.


DESIGN
Six week trial, consisting of three phases: screening (1 weeks), baseline period (1 week) and high fibre period (4 weeks).


SETTING
Western General Hospital, Edinburgh, Scotland.


SUBJECTS
Sixteen subjects from the hospital staff and student population were screened for breath methane (CH4) production. Seven non-CH4 producers, four males and three females, were included in the trial. All completed the study successfully.


INTERVENTION
Breath H2 and CH4 production were measured over a 12h period on duplicate test days after a low and high fibre meal. The high fibre meal was consumed for 4 weeks before the high fibre test days to allow for bacterial adaptation. The effect of the high fibre meal on stool output and whole gut transit time was furthermore assessed.


RESULTS
Individual differences in breath H2 area-under-the-curve between duplicate test days ranged from 4% to 39% after the low fibre meal and from 4% to 37% after the high fibre meal. Considerable variation was found to be inherent in the breath collection method. In two subjects, breath CH4 was detected in response to the test meals. Stool output and whole gut transit time remained unchanged.


CONCLUSION
Considerable differences were found between duplicate breath H2 responses to standard test meals. The variation inherent in the collection procedure emphasizes the need to collect breath samples at least in duplicate. The data presented here can be useful in future sample size calculations for similar studies.