Trends in Food Sources and Diet Quality Among US Children and Adults, 2003-2018

IMPORTANCE: Time trends and population disparities in nutritional quality of foods from major US sources, including grocery stores, restaurants, schools, worksites, and other sources, are not well established. OBJECTIVE: To investigate patterns and trends in diet quality by food sources among US children and adults overall and in sociodemographic subgroups. DESIGN, SETTING, AND PARTICIPANTS: This serial, cross-sectional survey study included respondents from 8 National Health and Nutrition Examination Survey cycles (2003-2018) with valid dietary recalls. Data were analyzed from April 16, 2020, to July 20, 2020. EXPOSURES: Survey cycle, food source, and key sociodemographic subgroups. MAIN OUTCOMES AND MEASURES: Mean diet quality of foods (meals, snacks, and beverages) consumed per person, characterized by the American Heart Association diet score (range, 0-80, with higher scores indicating healthier diets), the Healthy Eating Index 2015 (range, 0-100, with higher scores indicating healthier diets), and their components. For the American Heart Association diet score, poor diet was defined as less than 40.0% adherence (score, <32.0), intermediate diet as 40.0% to 79.9% adherence (score, 32.0-63.9), and ideal as 80.0% or greater adherence (score, ≥64.0). RESULTS: The study included 20 905 children 5 to 19 years of age (mean [SD] age, 12.1 [5.24] years; 51.0% male) and 39 757 adults 20 years or older (mean [SD] age, 47.3 [15.1] years; 51.9% female). Diet quality of foods consumed from grocery stores increased modestly in children (53.2% to 45.1% with poor diet quality; P = .006 for trend) and adults (40.1% to 32.9% with poor diet quality; P = .001 for trend), with smaller changes for restaurants among children (84.8% to 79.6% with poor diet quality; P = .003 for trend). Changes for restaurants among adults were not statistically significant (65.4% to 65.2% with poor diet quality; P = .07 with poor diet quality); the same was true of worksites (adults: 55.6% to 50.7% with poor diet quality; P = .25 for trend). Food quality from other sources worsened (children: 40.0% to 51.7% with poor diet quality; adults: 33.8% to 43.8% with poor diet quality; P < .001 for trend each). The largest improvement in diet quality was in schools, with the percentage with poor diet quality decreasing from 55.6% to 24.4% (P < .001 for trend), mostly after 2010, and with equitable improvements across population subgroups. Findings were similar for Healthy Eating Index 2015. Significant disparities in diet quality trends were seen by sex, race/ethnicity, educational level, and household income for food consumed from grocery stores. For example, the proportion of foods consumed from grocery stores that were of poor diet quality decreased among high-income adults (from 36.9% to 26.5%; P = .001 for trend) but not among low-income adults (from 45.8% to 41.3%; P = .09 for trend). CONCLUSIONS AND RELEVANCE: By 2017-2018, foods consumed at schools improved significantly and provided the best mean diet quality of major US food sources, without population disparities. Additional improvements are needed from all major US food sources, with particular attention on equity.