How Your Gut Produces and Uses Hydrogen Gas from Food
- Authors
- Stefan U. Christl, Peter R. Murgatroyd, Glenn R. Gibson, John H. Cummings
- Journal
- Gastroenterology
- Year
- 1992
- DOI
- 10.1016/0016-5085(92)70022-4
- Study Type
- Human
- Outcome
- Neutral
- Peer Reviewed
- Yes
- Country
- United Kingdom
- Health Condition
- Digestive Disorders
- Body System
- Digestive System
TL;DR
This study found that the amount of hydrogen gas produced in our intestines varies with different foods, and a significant portion is either breathed out or consumed by certain gut bacteria.
Key Finding
About 58% of hydrogen produced in the colon is exhaled in breath on average, which is higher than previously accepted, and this proportion varies depending on how much total hydrogen is being produced.
Summary
Researchers measured how much hydrogen gas is produced when food is fermented in the large intestine, and where that hydrogen goes—whether it's breathed out, passed as gas, or used by bacteria in the gut. They tested 10 healthy people and found that different foods (like lactulose, pectin, and starch) produce different amounts of hydrogen, and that bacteria in the colon consume some of the hydrogen that's produced. They also discovered that more hydrogen is breathed out than scientists previously thought.
Practical Takeaway
This study suggests that breath hydrogen tests—commonly used to diagnose food sensitivities—may underestimate how much hydrogen is actually being produced in the colon, since a significant amount is consumed by gut bacteria rather than exhaled. However, this is a small study in healthy people, so more research is needed to understand what this means for clinical testing and hydrogen water consumption.
Abstract
Hydrogen is produced during fermentation in the large intestine and may be excreted in breath and flatus or further metabolized by the flora. However, there is little information about total H2 excretion from different substrates or the extent to which it is metabolized in the colon. We have therefore measured total H2 and methane excretion in 10 healthy subjects using a whole body calorimeter. Breath gases were measured simultaneously with total excretion in response to lactulose, pectin, and banana starch. Metabolic activities of the predominant H2 consuming anaerobes (methanogenic, sulfate reducing, and acetogenic bacteria) were measured in fecal samples. Total H2 excretion on a starch and fiber-free diet was 35 +/- 6.1 mL/24 h +/- SEM. H2 from 7.5 g, 15 g, and 22.5 g lactulose was 88.1 +/- 22.4 mL, 227.0 +/- 60.7 mL, and 321.8 +/- 79.2 mL. Four of the subjects also excreted CH4, which was 51.3 +/- 5.5 mL, 97.3 +/- 18.4 mL, and 157.5 +/- 36.3 mL for the respective lactulose doses. H2 excretion was less in methanogenic subjects (7.9 mL/g lactulose) than in nonmethanogenic (17.3 mL/g), but total H2 excreted as, hydrogen + methane, was 34.9 mL/g. H2 from pectin (20 g) was 14.1% +/- 3.2% and from starch (22.2 g) 38.6% +/- 9.2% of an equivalent lactulose dose. Sixty-five percent of total H2 and CH4 was expired in breath at total excretion rates up to 200 mL/24 h. Over this the proportion decreased to 25% with an overall average of 58%. Only subjects with CH4 excretion in vivo showed methanogenesis in feces, whereas nonmethanogenic subjects showed high sulfate-reducing activity in feces (58.7 +/- 5.6 nmol 35SO4 reduced.h-1.g-1 wet wt vs. 7.9 +/- 2.0 nmol.h-1.g-1 in methanogens). Acetogenesis rates were very low in both groups. It was concluded that H2 excretion varies with different substrates. The proportion of H2 that is exhaled in breath is higher than currently accepted and varies with total excretion rate. Substantial amounts of H2 are consumed by methanogenic and sulfate-reducing bacteria.