Metabolomics: an emerging post-genomic tool for nutrition
Metabolomics is the study of the raw materials and products of the body’s biochemical reactions. Metabolomics is concerned with the analysis and measurement of global sets of low-molecular-weight compounds in urine, blood or some other body fluid, scanned in a NMR spectroscopy or Mass Spectrometer and to provide a profile of tens or hundreds of chemicals that can predict whether an individual vulnerable to a disease, or may develop side-effects from a particular drug. Such profiles may provide a more comprehensive view of cellular control mechanisms in man and animals, and raise the possibility of identifying surrogate markers of disease. Researchers are already trying to identify whether a person will develop specific diseases by measuring levels of gene expression or proteins, but supporters of metabolomics say they should be able to do it better. Small changes in the activity of a gene or protein (which may have an unknown impact on the workings of a cell) often create a much larger change in metabolite levels. The approach has already proved its worth: cholesterol and glucose have long been chemical indicators for heart disease and diabetes. Metabolomics has been made possible by the development of technologies that allow the function of cells and whole organisms to be explored at the molecular level. metabolites
Metabolomics has already been used to study toxicological mechanisms and disease processes and offers enormous potential as a means of investigating the complex relationship between nutrition and metabolism. Examples include the metabolism of dietary substrates, drug-induced disturbances of lipid metabolites in type 2 diabetes mellitus and the therapeutic effects of vitamin supplementation in the treatment of chronic metabolic disorders.
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But realising this vision isn’t straightforward. One of the first tasks is to create a catalogue of compounds in the human body, and this is proving hard to define. David Wishart at the University of Alberta, Edmonton, and his colleagues have taken an initial step forward by producing the first draft of the human metabolome. They searched the published literature for known human metabolites, and have collected around 2,500 of them into a public database (www.hmdb.ca).
However this may be an oversimplification. When the effect of age, gender, food physical makeup and chemical composition of diets rich in soya phyto-oestrogens on the absorption of the isoflavones was studied, urinary excretion of the metabolites was influenced by the isoflavone chemical make up of the diet , the sex of the person ingesting the food but not their age.
Nevertheless this is an exciting new area in Nutrition.
Terminology
Metabolomics The comprehensive analysis of the whole melabolome under a given set of conditions
Metabonomics: The quantitative measurement of time-related multiparametric metabolic responses of multicellular systems to pathophysiological stimuli or genetic modification
Metabolome The full set of low-molecular-weight metabolites within, or that can be secreted by, a given cell type or tissue
Metabolic fingerprinting The application of any technological approach whose output is processed with pattern-recognition software and without differentiation of individual metabolites
Lipidomics The characterisation of chemically distinct lipid species in cells and the molecular mechanisms through which they facilitate cellular function
Phillip D. Whitfield et al in British Journal of Nutrition 2004, 92, 549-555
Pearson H in Nature, 2007, 446, 8
Faughan MS et al in British Journal of Nutrition 2004, 91, 567-574

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