Metabolomics is a relatively new technology in the “omics cascade” that complements the existing omics-related methods. The science of metabolomics seeks to identify, quantify and understand fluctuations in the full range of metabolites in a defined biological system. Metabolomics can be defined as the quantitative measurement of all low molecular weight metabolites in an organism at a specified time under specific environmental conditions, where a metabolite is defined as a compound or molecule produced in or by a biological process. These extremely broad definitions adequately represent the challenges of metabolomics. It is analytically arduous to identify and quantify every metabolite in a biological system, especially as many of these compounds have not been previously reported and lack quantification standards. Towards this end, a number of different analytical approaches have been developed, including metabolic fingerprinting, metabolic profiling and metabolomics. Metabolic fingerprinting provides an overview or summary of a metabolite pattern in a disease or treated state versus control. There is often no compound identification or quantification. Instead, multivariate statistics are used to determine if the overall patterns differ significantly between the two systems. Metabolic profiling involves analyzing a structurally similar subset of the metabolome (e.g., lipidomics and glycomics). Global metabolomics implies the identification and subsequent quantification of all metabolites in the sample. The approach employed for an analysis depends upon the research question and available instrumentation. Metabolomics analyses rely upon a number of different analytical platforms depending upon the compounds being examined, including liquid chromatography (LC), gas chromatography (GC) and nuclear magnetic resonance (NMR). These instruments can be coupled to a wide range of detectors depending upon the analysis being conducted including mass spectrometer (MS), ultraviolet detector (UV) and flame ionization detector (FID) to list only a few. The ultimate choice of instrument depends upon the needs of the research question being addressed and the available research budget.

Metabolites are the products of gene expression and subsequent translation, thus integrating genomics and proteomics and providing a snapshot of the organism’s phenotype. These data are subsequently valuable when examining for biomarkers of disease, effects of therapeutic intervention or identification of disease state relative to control. In addition, these methods can be valuable in target selection for drug design. Metabolomics data can be combined with results from transcriptomics and proteomics studies to provide an integrated systems biology approach, giving a complete picture of a living organism. These studies are highly dependent upon developments in chemometrics, informatics and statistics. As with any of the other omics technologies that involve the collection of large-scale biological data sets, it is necessary to employ advanced statistical analyses for data interpretation. It is hoped that combining studies of the metabolome with the genome and proteome will highlight changes in biological networks and pathways, providing insights into physiological and pathological states.