January 31, 2008
People are Chemically Consistent
Evidence of different metabolic phenotypes in humans -- Assfalg et al., 10.1073/pnas.0705685105 -- Proceedings of the National Academy of Sciences shows that the biochemical differences between people are larger than the biochemical differences that occur from day to day due to diet, lifestyle and other factors. We seem to have metabolic fingerprints that at least don't change over the span of months. This might be useful for pharmacology, nutrition and medicine if we can figure out what metabolic fingerprints make us more or less vulnerable to different things.
The researchers took urine samples from 22 healthy volunteers over the span of three months. These were measured using NMR, and the spectra were then analysed using PCA, HCA, clustering and the usual statistical rigmarole.
I think the nicest diagram in the paper is this dendrogram, showing how close different samples are to each other. Different people have been given different colour, and the height of the branchings show how far away from each other the different clusters are. Clearly people are more chemically consistent with themselves than their "chemical neighbours".
I wonder if this could be used as biometrics? It might be individually reliable unless you happen to switch eating habits but just looking at a spectrum might not give enough dimensions to discriminate all people. Most likely it is best for research or as part of data fusion biometrics. But it would be amusing with high-security facilities that required peeing in a receptacle in order to open the security door...