Each of us is not a lone individual, but more like an ecosystem. The human "microbiome" contains 100 trillion microbes, ten hitchikers for each native cell in our bodies. In the last few years, doctors have been learning as much as they can about how these organisms interact with our metabolisms and immune systems, the better to target the most common killers from obesity to cancer to drug-resistant hospital infections. The Human Metabolome Project, not unlike the Human Genome Project, has identified over 40,000 "metabolites" found in the human body, consisting of gut flora, foods, drugs, hormones, and more. They have identified three "enterotypes," or broad categories of ecosystems thriving within the human gut.
In this crazy study, just published, doctors took another step in this process, taking "breathprints" of a small group of subjects which were individualized enough to provide more support for the concept of what the researchers called "metabolic phenotypes." By taking multiple samplings over several days, at different times of day or night, scientists ruled out random variations and created individual profiles based on such things as the concentrations of ethanol, acetone, and acetaldehyde in the breath. The smell of someone's breath has been a diagnostic tool in traditional Chinese medicine for thousands of years. Noninvasive and quick, one day breath sampling could take its place alongside urine or blood tests and be a great way to identify your metabolic type, zero in on disease risk, and optimize diet.