Meet another installment in biotech's "-omics" series: metabolomics. While doctors have been charting levels of individual metabolites like cholesterol for years, a growing number of researchers are measuring hundreds of metabolites-fatty acids, amino acids, and sugars produced by cells' everyday activities-more systematically. They say this will enable earlier diagnoses of a wide array of diseases and provide a set of new tools for developing safer drugs.

To identify the most meaningful metabolites of the thousands in the body, several companies are making systematic measurements of metabolites in sick and healthy people, hoping to pick out a few dozen, perhaps, that can become critical early markers for diseases, or for toxicity in drugs under development. In some ways, the research is a natural extension of the growing understanding of the body's many different genetic and molecular players, including genes and proteins. "We're just realizing now that we're looking at a small part of the picture by focusing on genomics and proteomics," says Jeremy Nicholson, head of biological chemistry at Imperial College in London, England. Genes, he says, only tell you the potential for something going wrong in the body, and proteins only tell you which genes have been turned on, but metabolites show "real-world changes. They show that something has really happened to the body."