Background Adolescence is a pivotal developmental stage, where escalating rates of overweight and obesity have raised concerns about diet quality and its association with later adverse health outcomes. Parents are known to have considerable influence on childhood diet, but how this influence changes as adolescents mature is unknown. This study investigates the association between parental and adolescent fruit and vegetable (FV) intake, exploring how this changes across adolescence and when adolescents leave the parental home.

Methods Adolescents aged 10-30 years (n=12,805) from the UK Household Longitudinal Study (UKHLS), and their parents, reported FV intakes every 2 years. Data were available at an average of 2 (SD: 1) waves for each participant. Living arrangement was updated every year during follow-up interviews. Multilevel linear regression models were fitted in R to assess associations between parental and adolescent FV intakes at each wave, investigating interactions with age and living arrangement, and adjusting for sociodemographic confounders including sex, ethnicity, parental education, household income and geographic region.

Results The mean age of adolescents across all waves was 17.4 years (SD: 5.6). The mean adolescent and parental FV intake were 2.92 (SD: 1.87) and 3.52 (SD: 1.95) portions per day, respectively. Parental FV intake was positively associated with adolescent FV intake (beta=0.20 [95%CI: 0.19, 0.22] portions/day). The strength of this association fluctuated across different adolescent stages, being lowest during early adolescence (10-14 years) and peaking at 17-18 years (beta=0.30 [95% CI: 0.27, 0.33] portions/day). When stratifying by living arrangement, the findings indicated that the association between parental and adolescent FV intake decreased for adolescents not living in their parental home. Nevertheless, the positive association between parental and adolescent FV persisted in both groups up to age 30 years.

Conclusion Our study highlights the sustained influence of parental dietary behaviour on adolescents up to age 30, even amongst those that have left their parental home. This suggests that interventions designed to promote healthier eating in adolescents should not only target adolescents but also consider the broader family context. Encouraging increased FV intake within families could leverage the enduring effect of parental modelling on dietary choices to instil healthy dietary practices in adolescents, even as they navigate the transition to independence.