OBJECTIVE: To analyze trends in levels of lipids and apolipoprotein B in US youths during 18 years from 1999 through 2016.

DESIGN, SETTING, AND PARTICIPANTS: Serial cross-sectional analysis of US population-weighted data for youths aged 6 to 19 years from the National Health and Nutrition Examination Surveys for 1999 through 2016. Linear temporal trends were analyzed using multivariable regression models with regression coefficients (β) reported as change per 1 year.

EXPOSURES: Survey year; examined periods spanned 10 to 18 years based on data availability.

MAIN OUTCOMES AND MEASURES: Age- and race/ethnicity-adjusted mean levels of high-density lipoprotein (HDL), non-HDL, and total cholesterol. Among fasting adolescents (aged 12-19 years), mean levels of low-density lipoprotein cholesterol, geometric mean levels of triglycerides, and mean levels of apolipoprotein B. Prevalence of ideal and adverse (vs borderline) levels of lipids and apolipoprotein B per pediatric lipid guidelines.

RESULTS: In total, 26 047 youths were included (weighted mean age, 12.4 years; female, 51%). Among all youths, the adjusted mean total cholesterol level declined from 164 mg/dL (95% CI, 161 to 167 mg/dL) in 1999-2000 to 155 mg/dL (95% CI, 154 to 157 mg/dL) in 2015-2016 (β for linear trend, -0.6 mg/dL [95% CI, -0.7 to -0.4 mg/dL] per year). Adjusted mean HDL cholesterol level increased from 52.5 mg/dL (95% CI, 51.7 to 53.3 mg/dL) in 2007-2008 to 55.0 mg/dL (95% CI, 53.8 to 56.3 mg/dL) in 2015-2016 (β, 0.2 mg/dL [95% CI, 0.1 to 0.4 mg/dL] per year) and non-HDL cholesterol decreased from 108 mg/dL (95% CI, 106 to 110 mg/dL) to 100 mg/dL (95% CI, 99 to 102 mg/dL) during the same years (β, -0.9 mg/dL [95% CI, -1.2 to -0.6 mg/dL] per year). Among fasting adolescents, geometric mean levels of triglycerides declined from 78 mg/dL (95% CI, 74 to 82 mg/dL) in 1999-2000 to 63 mg/dL (95% CI, 58 to 68 mg/dL) in 2013-2014 (log-transformed β, -0.015 [95% CI, -0.020 to -0.010] per year), mean levels of low-density lipoprotein cholesterol declined from 92 mg/dL (95% CI, 89 to 95 mg/dL) to 86 mg/dL (95% CI, 83 to 90 mg/dL) during the same years (β, -0.4 mg/dL [95% CI, -0.7 to -0.2 mg/dL] per year), and mean levels of apolipoprotein B declined from 70 mg/dL (95% CI, 68 to 72 mg/dL) in 2005-2006 to 67 mg/dL (95% CI, 65 to 70 mg/dL) in 2013-2014 (β, -0.4 mg/dL [95% CI, -0.7 to -0.04 mg/dL] per year). Favorable trends were generally also observed in the prevalence of ideal and adverse levels. By the end of the study period, 51.4% (95% CI, 48.5% to 54.2%) of all youths had ideal levels for HDL, non-HDL, and total cholesterol; among adolescents, 46.8% (95% CI, 40.9% to 52.6%) had ideal levels for all lipids and apolipoprotein B, whereas 15.2% (95% CI, 13.1% to 17.3%) of children aged 6 to 11 years and 25.2% (95% CI, 22.2% to 28.2%) of adolescents aged 12 to 19 years had at least 1 adverse level.