Detecting and identifying individual metabolites in biological mixtures constitutes a challenge in analytical research. In this context, nuclear magnetic resonance (NMR) has proven to be powerful providing precise qualitative and quantitative information non-invasively. However, NMR is inherently insensitive and lacks selectivity regarding the analysis of molecular targets in complex mixtures. Here, we present a method that circumvents these shortcomings performing photo-chemically induced dynamic nuclear polarisation (photo-CIDNP) on unmodified biofluids, i.e. human urine and serum. We demonstrate that photo-CIDNP on biofluids is feasible, can be performed straightforwardly in the native aqueous medium at physiological concentrations, and acts as a spectral filter highlighting a clinically relevant metabolite subset. The method is compatible with standard metabolomics protocols and holds great promise for in-depth studies for use in metabolomics and other areas of analytical research.