Challenges in Research in Nutritional Epidemiology

Diet is a complex aggregate of foods and behaviors. The food is constituted of a • wide variety of intended and unintended chemicals which may act singly on human metabolism, but more likely act in groups in a synergistic fashion. The study of nutrition and disease in aggregates of human beings—nutritional • epidemiology—is hampered by the dif fi culty in accurately characterizing this complex aggregate, that is, in stating what people are eating. Part of this dif fi culty is inherent in the large day-to-day variability in what is eaten. Another part of the dif fi culty relates to fi nding ef fi cient and accurate ways to collect dietary information, minimizing participant burden, and maximizing utility of the data for investigators. Much progress has been made in nutritional epidemiology in recent years owing • to the use of food frequency questionnaires, which pose little participant burden and are relatively easy to analyze. However, such data collection instruments are still characterized by high within-person variation and at the same time severely limit collection of important details about diet. A critical concept is whether the participant or the researcher synthesizes the • dietary information, including issues such as de fi ning the time period over which to average diet, what to do with unusual information, what constitutes a serving,