Association between dietary factors and health-related quality of life in adolescents longitudinally over three years from age 11-16 years

Background: Cross-sectional studies have linked adolescent food choices to health-related quality of life (HRQoL). This research aimed to determine the degree to which adolescent food choices are linked to health-related quality of life (HRQoL) longitudinally. Methods: HRQoL was assessed using the Kidscreen10 and food intake using a 17-item food frequency questionnaire (FFQ). Data were collected in the UK as part of the Wellbeing in Schools (WiSe) survey. Adolescents (N=2241) (49% female, n=1112) were surveyed at age 11-12 (2014); 13-14 (2016); 15-16 years (2018). Results: FFQ responses were reduced to five factors (junk food; fruit and vegetables; bread and dairy; meat; protein).Boys reported higher HRQoL than girls at age 13-14 and 15-16 years. Boys consumed ‘protein’ and ‘meat intake’ more frequently at all time-points. Girls reported more frequent ‘fruit and vegetable’ consumption at all time points, with intakes in boys becoming progressively less frequent at age 13-14 and 15-16 years.Cross-lagged panel modelling indicated that more frequent intake of ‘fruit and vegetables’, and ‘protein’ was associated with lower Kidscreen10 scores at baseline (age 11-12 years) and that this association strengthened through ages 13-14 and 15-16 years. Lower Kidscreen10 scores at baseline were associated with more frequent ‘bread and dairy’ intake at age 13-14 years but not at 15-16 years. No associations were observed over time between HRQoL and ‘junk food’ or ‘meat intake’. Conclusions: These findings imply the importance of earlier diet to quality of life later in adolescence. Further research is required to understand why certain dietary factors were associated with lower HRQOL over the course of adolescence. Meanwhile, intervention to enhance HRQoL should target girls while efforts to enhance ‘fruit and vegetable’ intake should target boys.