The association between dietary trajectories across childhood and blood pressure in early adolescence: The Longitudinal Study of Australian Children

Background: Cardio-metabolic risk factors, including hypertension, are increasingly appearing in childhood. The aims of this study were to examine the associations between dietary trajectories across childhood and subsequent blood pressure (BP) at age 10/11, and to further determine whether these associations were explained by BMI or fat mass. Methods: Data from 4360 participants from the Longitudinal Study of Australian Children were analysed. Dietary scores were computed based on similarity of intake to the Australian Dietary Guidelines. Group-based trajectory modelling was used to identify distinct dietary trajectories based on participant’s individual dietary scores at up to four timepoints between age 4 and 11. Linear regression models examined the associations between dietary trajectories and BP measured at age 10/11. Models were adjusted for relevant covariates, and BMI or fat mass. Results: Four dietary trajectories were identified: “never healthy” (4.3%); “moderately healthy” (23.1%); “becoming less healthy” (14.2%); and “always healthy” (58.4%). Children in the “always healthy” trajectory had a lower systolic (−2.19 mmHg; 95% CI −3.78, −0.59) and diastolic BP (−1.71; −2.95, −0.47), compared with children in the “never healthy” trajectory after covariate adjustment. These associations were attenuated after additional adjustment for BMI or fat mass, but remained significant for diastolic BP. Conclusions: A dietary trajectory mostly aligned with the Australian Dietary Guidelines across childhood was associated with slightly lower BP at age 10/11, which was not fully explained by BMI or fat mass. These findings support the need to encourage and enable healthy dietary habits early in childhood to attenuate the increasing burden of cardio-metabolic disease.