Researchers from the University of Alberta have shown that urine is a far more complex concoction than we ever imagined. The new comprehensive study chronicles the presence of over 3,000 chemicals in human urine — which is 30 times more than previously known.
Metabolomics is a relatively new area of study in which scientists look at the various chemicals (or metabolites) produced by cells and organisms. These chemicals are often the products of incredibly complex genome-wide and proteome-wide interactions, and they can often be used to measure and assess the health of an organism.
As is well known, urine is a remarkably useful biofluid that’s often used in medical testing. But until now, scientists have only documented about 50 to 100 chemicals in human urine, while most clinical urine tests only measure six to seven compounds. The new study, with its jaw-dropping revelation that there’s some 3,000 chemicals in urine, shows the huge potential that exists for more substantive uses of urine in clinical testing — including medical, nutritional, and environmental testing.
"Urine is an incredibly complex biofluid," noted David Wishart, the senior scientist on the project. "We had no idea there could be so many different compounds going into our toilets."
To perform the seven-year study, a Canadian research team consisting of 20 scientists used various analytical chemistry techniques to systematically identify and quantify all these compounds from a diverse set of human urine samples. Specifically, they used nuclear magnetic resonance spectroscopy, gas chromatography, mass spectrometry, and liquid chromatography. The team also used computer-based data mining techniques to sift through more than a hundred years worth of published literature about human urine.
The resulting chemical inventory, which includes chemical names, descriptions, structures, concentrations, and disease associations, is now freely available in the Urine Metabolome Database (UMDB). This database now contains the complete set of 2,651 confirmed human urine metabolite species, along with their structures, of which there's 3,079.
Relatedly, the PLoS Human Microbiome Project Collection provides a comprehensive catalog of the nearly 5 million microbes that reside in the human body.
Eventually, this information could be used to develop more comprehensive protocols for urine testing. The database will be of great interest to physicians, nutritionists, and environmental scientists as they will be better able to gauge the state of a person’s health, the influence of the foods that they are eating and drinking, what drugs they may be taking (i.e., illicit drugs), and what pollutants they may have been exposed to.
"Expanding the list of known chemicals in urine by a factor of 30 and improving the technology so that we can detect hundreds of urine chemicals at a time could be a real game-changer for medical testing," said Wishart.
Read the entire study for free at PLoS One: “The Human Urine Metabolome.”
Top image: Csaba Deli/Shutterstock.