Breath ammonia and ethanol increase in response to a high protein challenge.

Quantifying changes in ammonia and ethanol in blood and body fluid assays in response to food is cumbersome. We used breath analysis of ammonia, ethanol, hydrogen (an accepted standard of gut transit) and acetone to investigate gastrointestinal physiology. In 30 healthy participants, we measured each metabolite serially over 6 h in control and high protein trials. Two-way repeated measures ANOVA compared treatment (control versus intervention), change from baseline to maximum and interaction of treatment and time change. Interaction was significant for ammonia (p < 0.0001) and hydrogen (p < 0.0001). We describe the dynamic measurement of multiple metabolites in response to an oral challenge.