Interrogating Theories and Mechanisms Underlying Educational Inequities in Diet Quality.

Educational inequities in diet quality are large and growing in several nations. However, there is limited understanding of theories and mechanisms through which educational attainment shapes diet quality. The purpose of this critical review is to interrogate the empirical support for theories and mechanisms underlying educational attainment as a structural stratifier of dietary inequities in high-income countries. Relevant studies were identified through searches in PubMed and Google Scholar using keywords related to educational attainment, inequities, diet quality, nutrition, theory, mechanisms, health, and mortality. The evidence was qualitatively synthesized to identify key theories and mechanisms relevant to educational inequities in diet quality. We identified 7 theoretical perspectives that are commonly invoked to explain educational inequities in health-related outcomes that are relevant to diet quality, including: fundamental cause theory, human capital theory, signaling theory, commodity theory, resource substitution theory, resource multiplication theory, and the psychosocial hypothesis. We also identified 5 categories of mediating mechanisms that might underlie educational inequities in diet quality, including 1) individual knowledge, cognitive and noncognitive skills and traits, and sense of personal control; 2) psychosocial factors; 3) economic and employment resources; 4) socioeconomic, political, and historical contexts; and 5) social distinction. We identify and describe 7 key theories and 5 major mechanisms that may contribute to educational inequities in diet quality. These theories and mechanisms are not mutually exclusive and are likely all implicated in educational inequities in diet quality to some extent. However, their relative importance differs depending on the time, population, and setting in which they are studied. Given the paucity of studies that have examined theories and mechanisms underlying educational inequities in diet quality, we hope this article will stimulate research to uncover these pathways and that such studies will extend beyond economic and knowledge-related mechanisms.