Human urinary metabolic profiling showed to be very successful to elucidate biomarkers linked to geographic origin and specific food consumption patterns (Holmes and Loo et al.: Human metabolic phenotype diversity and its association with diet and blood pressure. Nature 2008:1-6). It was possible to identify urinary metabolites directly linked to animal vs. vegetable protein intake. This is very valuable for future population studies, where diet is an important lifestyle factor but food questionnaires are time-consuming and expensive. Moreover, miss-reporting is a very common problem.