Metabolomics: the greatest omics of them all?

Is metabolomics the greatest 'omics' of all? Certainly, it has been suggested that metabolomics may in fact provide the most 'functional' information of the omics technologies.1 This reflects the limitations associated with transcriptomics and proteomics; for example, changes in the transcriptome and proteome do not always result in altered biochemical phenotypes (the metabolome).1,2 Furthermore, the metabolome represents the final 'omic' level in a biological system, and metabolites represent functional entities, unlike messenger RNA molecules, which constitute the transcriptome.3 Metabolites thus have a clear function in the life of the biological system and are also contextual,3 reflecting the surrounding environment. The metabolome can thus be thought of as a looking glass, which if looked through can show information concerning the physiological, developmental, and pathological status of a biological system.