Metabolic phenotyping is a scientific research strategy to understand the interactions between the genotype, environment and lifestyle at the molecular level.
The metabolites in the human body (for example, carbohydrates, lipids and prescribed drugs) are connected via a metabolic network with each node being a metabolite and each edge, connecting two metabolites, being a metabolic reaction. The complete collection of metabolites is defined as the metabolome and the human body can be separated in to biofluid- or tissue-specific metabolomes; for example the urine metabolome is metabolically different to the blood metabolome. The size of the human metabolome, an integration of all the different metabolomes in the body, is estimated to be greater than 40,000 metabolites.
Why do metabolites provide an approach to investigate the phenotype? The genome acts to provide information to construct structures and other biochemicals in the human body. The genome is relatively constant during your lifetime, with only small changes related to mutations and single nucleotide polymorphisms. The metabolome can be defined as the final downstream product of gene transcription with metabolites being involved in metabolism, acting as precursors for the synthesis of proteins, RNA and DNA, and also acting in regulatory and signalling pathways. Importantly, and unlike the genome, the metabolome is highly dynamic in nature and responds rapidly to changes in the environment. For example, if you sprinted for ten seconds your muscle and blood metabolomes would be different before and after that sprint (including increased lactic acid concentrations) showing how the environment impacts on the human metabolome rapidly.
We can use this advantage of the metabolome being dynamic and sensitive to environmental stimuli and lifestyle changes to understand mechanisms of human diseases or to identify metabolic markers to be applied for prognosis, diagnosis and treatment response in stratified medicine.