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

Abstract

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.

Figure 1.. Trends in Estimated Proportions of US Youth Aged 2 to 19 Years With Poor, Intermediate, or Ideal Diet Quality

Trends are according to the American Heart Association (AHA) 2020 Strategic Impact Goals, based on a continuous scoring system by National Health and Nutrition Examination Survey (NHANES) cycles from 1999-2000 to 2015-2016. The primary score is based on total fruits and vegetables, whole grains, fish and shellfish, sugar-sweetened beverages, and sodium, and the secondary score further adds nuts, seeds, and legumes, processed meat, and saturated fat. Data were weighted to be nationally representative. Data points indicate estimated percentages; error bars, 95% CIs. For dietary quality based on the AHA primary score, P < .001 for trend for poor (decrease) and intermediate (increase) quality and P = .03 for ideal quality (increase). For dietary quality based on the AHA secondary score, P< .001 for trend for poor (decrease) and intermediate (increase) quality and P = .03 for ideal quality (increase).

Figure 2.. Changes in Estimated Mean Consumption of Dietary Components Among US Youth Aged 2 to 19 Years

Based on National Health and Nutrition Examination Survey (NHANES) data from 1999-2000 to 2015-2016. Data represent estimated mean change in population dietary intake from 1999-2000 to 2015-2016. The analyses were based on energy-adjusted values to 2000 kcal/d using the residual method. P values for trend were estimated across all NHANES cycles from 1999 to 2016.

Figure 3.. Trends in Estimated Mean Consumption of Key Food Groups and Nutrients Among US Youth Aged 2 to 19 Years by NHANES Cycles From 1999-2000 to 2015-2016

Data are weighted to be nationally representative. Data points indicate estimated means; error bars, 95% CIs. Added sugar: 1 tsp = 4.2 g. Analyses were based on energy-adjusted values to 2000 kcal/d using the residual method. P < .001 for trend for whole fruits (increase), 100% fruit juices (decrease), white potatoes (decrease), tomatoes (decrease), dark-green vegetables (increase), milk (decrease), cheese (increase), yogurt (increase), poultry (increase), whole grains (increase), sugar-sweetened beverages (decrease), and added sugar (decrease). Other significant trends were observed for other red or orange vegetables (increase; P = .03 for trend) and unprocessed red meat (decrease; P = .01 for trend). Trends for the remaining dietary components remained stable.