Background and aimsA relationship exists between dietary copper intake and hypertriglyceridemia in the United States (US). However, children and adolescents have there is limited research data for children and adolescents, who have not been thoroughly investigated. This study aimed to carefully evaluate this relationship. Methods and resultsThis cross-sectional study included 3982 children and adolescents who participated in the US National Health and Nutrition Examination Survey 1999–2006. The outcome variable was hypertriglyceridemia, defined as a triglyceride (TG) concentration >150 mg/dL. Multivariate and binary logistic regression models were applied in this study. The median (Q1–Q3) copper intake and TG levels were 0.98 (0.71–1.32) mg/d and 72.00 (53.00–100.00) mg/dL, respectively. The smoothing curve showed an inverted L-shaped relationship between copper intake and the prevalence of hypertriglyceridemia in American children and adolescents. A binary logistic regression model was developed to evaluate the relationship between copper intake and the prevalence of hypertriglyceridemia, and the inflection point was 0.76 mg/d. The odds of developing hypertriglyceridemia significantly increased with increasing levels of copper intake (odds ratio (OR), 2.00; 95% confidence interval (CI): 1.39–2.86) in participants with copper intake >0.76 mg/d (P for log likelihood ratio test = 0.032). The association between high copper intake and increased hypertriglyceridemia risk was significantly stronger in participants with a high body mass index (BMI; ≥23 kg/m2) (OR: 2.09; 95% CI: 1.42–3.07) than in those with a low BMI (tertile 1–2) (p for interaction = 0.048). Moreover, the increase in copper intake in adolescents aged 13–18 years significantly increased the prevalence of hypertriglyceridemia (OR: 1.95; 95% CI: 1.38–2.76; p for interaction = 0.001). ConclusionHigher dietary copper intake increases the prevalence of hypertriglyceridemia, especially among US adolescents with a BMI ≥23 kg/m2.