Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Lipidomics and lipid profiling in metabolomics J. Bruce German a , Laura A. Gillies a , Jennifer T. Smilowitz a , Angela M. Zivkovic a and Steven M. Watkins b Purpose of review The field of metabolomics is extending the principles of genomics into cellular and organism metabolism and driving a revolution in lipid biochemistry, physiology and nutrition. Lipids studied using metabolomic approaches – lipidomics – are an ideal subject for metabolomic measurements. Recent findings Lipids are small molecules that share common physical and chemical properties as a class, whose presence and abundance are key to much of metabolic regulation, from subcellular compartments to whole body energy control and signaling. Furthermore, by measuring changes in lipid concentrations, scientists are gaining a more detailed understanding of biochemistry and thus annotating genomes, but also understanding genetic polymorphisms and the postgenetic effects induced by drugs, foods and toxins. Summary Although in its infancy – there are fewer than 200 total articles on lipidomics and metabolomics focusing on lipids – the field of metabolomics is beginning to deliver on its promise to revolutionize lipid and metabolic disease research. Keywords drug development, lipidomics, metabolites, metabolomics, personalized medicine, profiling Curr Opin Lipidol 18:66–71. ß 2007 Lippincott Williams & Wilkins. a Department of Food Science and Technology, University of California, Davis and b Lipomics Technologies, 3410 Industrial Boulevard, West Sacramento, California, USA Correspondence to J. Bruce German, Department of Food Science and Technology, University of California, Davis, CA 95616, USA Tel: +1 530 752 1486; fax: +1 530 752 4759; e-mail: jbgerman@ucdavis.edu Current Opinion in Lipidology 2007, 18:66–71 ß 2007 Lippincott Williams & Wilkins 0957-9672 Introduction This review highlights recent advances in metabolomics of interest to drug discovery and development and personalized medicine. Lipids are among the least under- stood of the cellular biomolecules. Even in the era of genomics, lipids continue to be an underappreciated subset of the metabolome. Fundamental questions about lipids, whose conceptual counterparts were answered for proteins decades ago, remain. Lipids within membranes exist as complex structural aggregates whose integrity provides multiple functions. This new view of the membrane as a functional network of lipid aggregates poses many questions. Which lipids exist within specific membranes and in what aggregate structures? How do these aggregate structures assemble and dissociate? What are the functions of these structural aggregates and what are the consequences to cells and organisms when they fail to function normally? How do lipids contribute to the signaling within cells and between cells and organelles? How do cells sort lipids to their multiple roles as struc- tures, signals and fuel molecules? Answering these ques- tions will fundamentally change our understanding of basic biology, of intervening in the health of humans and guiding biotechnology to improve the human condition. The technical strategies for metabolomics, and espe- cially lipidomics, are surprisingly undeveloped in the ‘omics’ era. Why is this surprising? In retrospect, meta- bolomics should have been the highest priority of systems biology. The knowledge of the biochemical pathways that use and produce metabolites is extensive. There is a long history of successful application of metabolites as measured biomarkers (blood cholesterol, glucose, triglycerides), and the technologies to measure metabolites have been in place for decades, certainly long before sequencing and immobilized nucleotide arrays. Furthermore, variations in human health and disease as well as exogenous influences on health (age, pathogens, toxins, diet and drugs) are reflected in metabolism. The new strategy of measuring all, or subsets of, metabolites provides considerable advantage over focused single metabolite measurements for basic research, health research and assessment, and even discovery of the functions of genes and genomes [1–5]. Now the strategies and toolsets of genomics are being applied to lipids, and the field of lipid- omics is emerging. High-resolution chromatography, mass spectrometry, nuclear magnetic resonance are making lipomics possible. 66