Changes in diet quality across life transitions from adolescence to early adulthood: a latent growth analysis.

Background: Adolescence to early adulthood is a period of multiple education-, employment- and family-related life transitions. Changing resources and food environments within the context of these transitions could contribute to significant changes in diet, which persist into later adulthood. This study investigated diet quality trajectories from age 15 to 31 years and changes in diet quality associated with life transitions, by sex. Methods: Data from the Project EAT (Eating and Activity in Teens and Young Adults) study were used to examine diet quality among a longitudinal cohort (n=2,524) across four waves (mean ages of 15, 19, 25 and 31 years). Diet quality was evaluated using the DASH (Dietary Approaches to Stop Hypertension) index. Life transitions were assessed by changes in life circumstances between pairs of waves, including leaving the parental home, leaving full-time education, beginning full-time employment, cohabitating with a partner, and becoming a parent. Average within-person changes in DASH scores were analysed by sex-specific latent growth models, incorporating underlying growth trajectories, five life transitions and baseline socio-demographic characteristics. Results: Both sexes followed a quadratic trajectory of DASH scores, showing decreases in diet quality from waves 1 to 2 followed by increases until wave 4. Compared to females, males had worse diet quality at wave 1, and this sex difference widened at wave 4. Leaving the parental home between waves 1 and 2 was associated with transient decreases in diet quality at wave 2 only for males. For females, cohabitating with a partner and becoming a parent between waves 3 and 4 were respectively related to decreases and increases in diet quality at wave 4. Leaving full-time education and starting full-time employment respectively had long-term negative and positive associations with diet quality for both sexes. Conclusions: Diet quality remained suboptimal throughout adolescence but to some extent improved across early adulthood. A sex-sensitive approach in public health policy is welcome for addressing sex differences in diet quality and dietary changes associated with family-related life transitions. Targeted dietary interventions are beneficial for young people who leave their parental home early or who do not enter into a structured school or workplace environment.