Trends in Diet Quality Among Youth in the United States, 1999-2016

IMPORTANCE Prior studies of dietary trends among US youth have evaluated major macronutrients or only a few foods or have used older data. OBJECTIVE To characterize trends in diet quality among US youth. DESIGN, SETTING, AND PARTICIPANTS Serial cross-sectional investigation using 24-hour dietary recalls from youth aged 2 to 19 years from 9 National Health and Nutrition Examination Survey (NHANES) cycles (1999-2016). EXPOSURES Calendar year and population sociodemographic characteristics. MAIN OUTCOMES AND MEASURES The primary outcomes were the survey-weighted, energy-adjusted mean consumption of dietary components and proportion meeting targets of the American Heart Association (AHA) 2020 continuous diet score (range, 0-50; based on total fruits and vegetables, whole grains, fish and shellfish, sugar-sweetened beverages, and sodium). Additional outcomes were the AHA secondary score (range, 0-80; adding nuts, seeds, and legumes; processed meat; and saturated fat) and Healthy Eating Index (HEI) 2015 score (range, 0-100). Poor diet was defined as less than 40% adherence (scores, <20 for primary and <32 for secondary AHA scores); intermediate as 40% to 79.9% adherence (scores, 20-39.9 and 32-63.9, respectively); and ideal, as at least 80% adherence (scores, >= 40 and >= 64, respectively). Higher diet scores indicate better diet quality; a minimal clinically important difference has not been quantified. RESULTS Of 31 420 youth aged 2 to 19 years included, the mean age was 10.6 years; 49.1% were female. From 1999 to 2016, the estimated AHA primary diet score significantly increased from 14.8 (95% CI, 14.1-15.4) to 18.8 (95% CI, 18.1-19.6) (27.0% improvement), the estimated AHA secondary diet score from 29.2 (95% CI, 28.1-30.4) to 33.0 (95% CI, 32.0-33.9) (13.0% improvement), and the estimated HEI-2015 score from 44.6 (95% CI, 43.5-45.8) to 49.6 (95% CI, 48.5-50.8) (11.2% improvement) (P <.001 for trend for each). Based on the AHA primary diet score, the estimated proportion of youth with poor diets significantly declined from 76.8%(95% CI, 72.9%-80.2%) to 56.1%(95% CI, 51.4%-60.7%) and with intermediate diets significantly increased from 23.2%(95% CI, 19.8%-26.9%) to 43.7%(95% CI, 39.1%-48.3%) (P <.001 for trend for each). The estimated proportion meeting ideal quality significantly increased but remained low, from 0.07%(95% CI, 0.01%-0.49%) to 0.25%(95% CI, 0.10%-0.62%) (P =.03 for trend). Persistent dietary variations were identified across multiple sociodemographic groups. The estimated proportion of youth with a poor diet in 2015-2016 was 39.8%(95% CI, 35.1%-44.5%) for ages 2 to 5 years (unweighted n = 666), 52.5%(95% CI, 46.4%-58.5%) for ages 6 to 11 years (unweighted n = 1040), and 66.6%(95% CI, 61.4%-71.4%) for ages 12 to 19 years (unweighted n = 1195), with persistent differences across levels of parental education, household income, and household food security status. CONCLUSIONS AND RELEVANCE Based on serial NHANES surveys from 1999 to 2016, the estimated overall diet quality of US youth showed modest improvement, but more than half of youth still had poor-quality diets.