Since the last part of the twentieth century, scientists began to look at biological systems in a more holistic way. The holistic or global view of biological systems is the key to ‘omics’ research. In addition to holistic approaches, a paradigm shift started to occur whereby it is believed that the genetic blueprint alone cannot explain biological systems or phenotypes, especially in relation to their environment and all related perturbations.
The metabolome is the final downstream product of the genome and is closest to the functional phenotype of the cell or organism. The metabolome is thus also closer to the environment and more susceptible to external perturbations. Study thereof can give more direct answers than the proteome or transcriptome as many studies have shown - where alterations of metabolites was observed even when alterations in the concentrations of proteins and transcripts were not detectable.
Furthermore, analysis of the metabolome looks more attractive than the analysis of the proteome or transcriptome from the view point that it consists of < 10 000 estimated small molecules (metabolites) in contrast to the millions or tens of thousands of proteins, transcripts and genes.