Diet quality indices and the need for more validation studies.

Fundamental to the study and practice of nutrition is the understanding that nutritional status and nutrition-related health are not just the result of exposure to individual nutrients found in the diet, but also the complexity of interactions between nutrients and non-nutrient components in foods. This has prompted the relatively recent study of diet quality as an index for assessing the relationship between dietary exposures and health outcomes. Diet quality measurement involves assessing how well diet patterns align with national dietary guidelines and how diverse the variety of healthy choices is within core food groupings. In this issue, Wirt and Collins present a comprehensive review of diet quality indices and find a range of limitations when comparing and interpreting results, supporting their recommendation that more research on validating diet quality indices is needed.