Published online Jan 28, 2016. doi: 10.3748/wjg.v22.i4.1639
Peer-review started: August 10, 2015
First decision: September 29, 2015
Revised: October 11, 2015
Accepted: November 13, 2015
Article in press: November 13, 2015
Published online: January 28, 2016
Volatile organic compounds (VOCs) emitted from stool are the components of the smell of stool representing the end products of microbial activity and metabolism that can be used to diagnose disease. Despite the abundance of hydrogen, carbon dioxide, and methane that have already been identified in human flatus, the small portion of trace gases making up the VOCs emitted from stool include organic acids, alcohols, esters, heterocyclic compounds, aldehydes, ketones, and alkanes, among others. These are the gases that vary among individuals in sickness and in health, in dietary changes, and in gut microbial activity. Electronic nose devices are analytical and pattern recognition platforms that can utilize mass spectrometry or electrochemical sensors to detect these VOCs in gas samples. When paired with machine-learning and pattern recognition algorithms, this can identify patterns of VOCs, and thus patterns of smell, that can be used to identify disease states. In this review, we provide a clinical background of VOC identification, electronic nose development, and review gastroenterology applications toward diagnosing disease by the volatile headspace analysis of stool.
Core tip: Electronic noses, which include analytical spectrometric platforms and pattern recognition devices, can be used to diagnose disease by analysis of volatile organic compounds generated by the microbiome and the end products of metabolism in the fecal headspace gas.