Until very recently, phytonutrient research was the province of natural product chemists and consisted of primarily anecdotal clinical references. In recent years, an extensive set of qualitative and semi-quantitative dietary epidemiologic data has been developed. This developing base of epidemiologic data is now being supplemented by biochemical, mechanistic, and genetic epidemiology of a more quantitative nature. As we seek to understand the mechanisms that explain a large body of epidemiologic evidence, newer laboratory methods continue to be developed. Though there is a continuing need for even more discriminating nutrition epidemiology to drive the basic research in this area forward, the focus of in vitro, animal and clinical (human) studies must continue to be refined, and appropriate biomarkers for chronic and acute (death) disease end-points must be developed.