Dietary patterns and trends in the United States: the UNC-CH approach.

Over the past 2 decades our group of nutrition and economics researchers at the University of North Carolina at Chapel Hill has used a wide array of methods to study eating patterns and dietary trends. Our focus has been on characterising the way diet has changed over time and identifying some of the major factors underlying these trends. The complexity of this undertaking has led us to develop a number of unique systems for classifying foods and assessing the overall quality of diet. We have also addressed the challenges that exist when measuring changes in both the food supply and food-related behaviors over time. This paper summarises some of the methodological work related to food grouping, overall diet quality indices, and trends research as well as the challenges we still face in this arena.