This work focuses on the key issues of design and analysis in studies which aim to relate measures of nutritional exposure to disease outome. The first section discusses how to identify the appropriate measures of exposure and outcome in order to formulate a clear research hypothesis, including the questions of power and sample size. This is followed by a detailed discussion of how to measure the exposures and outcomes with the desired degree of accuracy. Particular emphasis is placed on the identification of measurement error and confounding factors, and how to cope with their influence on the observed relationships. The final section addresses the problem of design and interpretation that arise in epidemiological studies - ecological, case-control, cohort and experimental - which include measures of nutritional exposure. The need for this book arises because of the complexity of nutritional exposures. By learning how to identify relevant measures of nutritional exposure and measure them correctly in epidemiological studies, we improve our ability to assess the role of nutrition in disease aetiology.