For the third study, Rist et al. , fasting blood and urine samples were analyzed by non-targeted comprehensive two-dimensional gas chromatography (GC×GC)-MS, different targeted GC-MS and LC-MS/MS methods as well as 1H-NMR, for 301 healthy (BMI between 17.8-31.4 kg/m2) men and women; these included 172 men and 129 women (out of which 73 were considered to be postmenopausal) (total group 47.5 ± 17.1 y of age); no information was presented on the ethnicity of the participants. For plasma, more than 400 metabolites were identified, and for urine more than 500, out of which in total 14 were found to be age-related for both fluids independent of sex and therefore used in this analysis. These markers were determined by three machine learning methods, support vector machine (SVM) with linear kernel, generalized linear model net (glmnet), and Partial Least Squares (PLS). In total 19 identifiers were found for these 14 compounds, since several names could be connected to multiple identifiers due to small differences in stereochemistry, e.g. D-Ornithine (Q27077099), L-Ornithine (Q410198), and DL-Ornithine (Q27102952). Thirteen of these identifiers represented plasma biomarkers and six urine.