Combined Urinary Biomarkers to Assess Coffee Intake Using Untargeted Metabolomics: Discovery in Three Pilot Human Intervention Studies and Validation in Cross-Sectional Studies.

Coffee is a widely consumed beverage worldwide and has a high content of chlorogenic acids, polyphenols, methylxanthines, and volatile flavor compounds. Scientific evidence to support the beneficial health effects of coffee is limited, and validated urinary biomarkers of coffee intake are therefore needed. We observed 23 common putative biomarkers of coffee intake in three separate parallel intervention studies by ultra-high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry (UHPLC-ESI-QTOF-MS) and multivariate analyses. Baseline samples from the NU-AGE study were used to confirm and validate 16 of these candidate biomarkers, including their robustness, time response, and dose response. These validated candidate biomarkers are N-methylpyridinium cation, 1-methyl-1H-pyrrole-2-carboxaldehyde, 1H-pyrrole-2-carboxaldehyde sulfate, 3-piperidinemethanol, furfurylidene-furfurylamine, 2-furoylglycine, N-substituted-5-(aminoethyl) furan-2-carbaldehyde derivative, 3',4'-dihydroxyacetophenone sulfate, caffeine, dihydroxystyrene glucuronide, ferulic acid sulfate, 4-ethylcatechol glucuronide, 3-feruloylquinic acid, 3,4-dihydroxystyrene sulfate, one unknown glucuronide, and one unknown sulfate. Combinations of candidate biomarkers gave a better prediction of coffee consumption than individual biomarkers. The robustness of the combined biomarkers requires additional validation in cohort studies covering other populations.