Association Between Diet Quality and Metabolic Syndrome in US Adolescents Aged 12 to 18 Years

Background: Metabolic syndrome is a group of risk factors that, if unaddressed, can lead to various non-communicable diseases such as cardiovascular disease and type 2 diabetes. Previous studies have shown that there is an association between diet and metabolic syndrome. As poor diet and obesity are increasingly prevalent in adolescent populations, adolescents become more at risk of developing metabolic syndrome at an earlier age. This study examined the association between diet quality, as measured by healthy eating index (HEI), and metabolic syndrome in US adolescents aged 12 to 18 years.Methods: The analytic sample consisted of 1,178 adolescents aged 12 to 18 years who participated in NNHANES cycles between 2011 and 2016. Healthy eating index was constructed using information from the NHANES 24-hour dietary recalls, as well as the USDA’s Food Patterns Equivalents Database. HEI was scored continuously on a scale from 0-100. I then categorized participants into quintiles by HEI for further analysis. Metabolic syndrome was measured using data from a variety of NHANES databases using standards for diagnosis of metabolic syndrome in adolescents established in previous NHANES studies. I examined the association between HEI and metabolic syndrome using adjusted and unadjusted logistic regression models. The adjusted model included the covariates age, gender, BMI, ethnicity, household size, income-to-poverty ratio, and physical activity. Finally, I performed a sensitivity analysis to investigate whether the definition of metabolic syndrome used for adolescents was appropriate. Results: HEI was not significantly associated with metabolic syndrome in adolescents when treated as a continuous predictor. When treated as a categorical predictor, only those in the highest quintile of HEI had significantly lower odds of metabolic syndrome (odds ratio [OR] = 0.28; 95% confidence interval [CI]: 0.10, 0.81). The frequency of metabolic syndrome in this quintile was 4.68 percent. The sensitivity analysis found that there was no significant difference in results when using the current diagnosis standards for metabolic syndrome versus more relaxed standards (only 2 symptoms present versus 3). Conclusions: This study found preliminary evidence to support the hypothesis that healthy eating index is inversely associated with risk of metabolic syndrome in adolescents aged 12 to 18 years in the United States. This may be because diet is an important risk factor in the development of the 5 indicators of metabolic syndrome. Adolescents with metabolic syndrome are at higher risk for metabolic syndrome, heart disease, and type 2 diabetes as adults. Therefore, prevention and management of this condition in adolescence is important to change the trajectory of adolescents’ health. A healthy diet in alignment with the USDA’s Dietary Guidelines is beneficial for all adolescents to develop healthy lifestyle habits. Future research should investigate the use of nutrition education and counseling as a tool for metabolic syndrome treatment and prevention in this population.