Healthy dietary habits score as an indicator of diet quality in New Zealand adolescents

Adoption of optimal dietary habits during adolescence is associated with better health outcomes later in life. However, the associations between a pattern of healthy dietary habits encapsulated in an index and sociodemographic and nutrient intake have not been examined among adolescents. This study aimed to develop a behavior-based diet index and examine its validity in relation to sociodemographic factors, nutrient intakes, and biomarkers in a representative sample of New Zealand (NZ) adolescents aged 15-18 y (n = 694). A 17-item Healthy Dietary Habits Score for Adolescents (HDHS-A) was developed based on dietary habits information from the 2008/2009 NZ Adult Nutrition Survey. Post hoc trend analyses were used to identify the associations between HDHS-A score and nutrient intakes estimated by single 24-h diet recalls and selected nutritional biomarkers. Being female, not of Maori or Pacific ethnicity, and living in the least-deprived socioeconomic quintile were associated with a higher HDHS-A score (all P < 0.001). HDHS-A tertile was associated positively with intake of protein, dietary fiber, polyunsaturated fatty acid, and lactose and negatively with sucrose. Associations in the expected directions were also found with most micronutrients (P < 0.05), urinary sodium (P < 0.001), whole blood (P < 0.05), serum (P < 0.01), and RBC folate (P < 0.05) concentrations. This suggests that the HDHS-A is a valid indicator of diet quality among NZ adolescents.