Background. Evidence regarding an individual`s food and nutrition literacy (FNL), and its impact on dietary behaviours, could guide the development of more effective interventions. This study sought to examine the association between FNL and its components with diet quality and nutrient density among Iranian senior highschool students.

Methods. In this cross-sectional study, 755 senior high school students were recruited from high schools in Tehran, Iran. FNL was assessed using the Food and Nutrition Literacy Assessment Tool (FNLAT), a selfadministered questionnaire which has been locally designed and validated. Dietary assessment was performed by obtaining two 24-hour dietary recalls. Healthy Eating Index-2010 (HEI-2010) and nutrient-rich food index 9.3 (NRF9.3) were calculated to evaluate diet quality. Socioeconomic status, anthropometric measures, and the health status of participants were also assessed.

Results. Higher FNL score was significantly correlated with higher HEI-2010 (β = 0.167, p < 0.001) and NRF9.3 (β = 0.145, p < 0.001) scores. Subgroup analysis indicated that these associations were significant only among males, but not females. Regarding components of FNL, skill dimension of FNL was a stronger predictor for HEI- 2010 (β = 0.174, p < 0.001) and NRF9.3 (β = 0.153, p < 0.001) than knowledge (β = 0.083, p = 0.054 for HEI-2010 and β = 0.107, p = 0.01 for NRF9.3).

Conclusions. FNL may be a significant predictor of diet quality and nutrient density among late adolescents. To improve the effectiveness of food and nutrition education, emphasis must be placed on skill development.

Keywords: adolescents, diet quality, food literacy, nutrient density, nutrition literacy