Dietary trajectories through the life course: opportunities and challenges

Studying the dynamic patterns of dietary changes or stability (otherwise known as dietary trajectories) across the life course can provide important information about when and in whom to intervene with nutritional interventions. This article reviews evidence from longitudinal studies that describe dietary trajectories through the different life stages, covering early life, adolescence to young adulthood and from mid to late adulthood. Current findings suggest that the establishment of diet patterns likely occurs before 3 years of age and allude to other potential 'windows of change' in the life course such as the period of 7-9 years of age and during the period of adolescence and early adulthood. Examining diets using various diet parameters appears to be valuable in elucidating different aspects of the diet that can be changed to potentially alter trajectories. In adults, examining long-term diet trends at a population level can reveal shifts in eating patterns as countries undergo epidemiological and nutrition transitions and elucidate the longer-term impact of adherence to particular diets on the development of chronic diseases. While challenges such as the availability of adequate diet data points, consistency in the dietary assessment tools used and the limitations of statistical methods for trajectory modelling remain, integrating diet data with other lifestyle behaviours, high-dimensional biomarkers and genetics data into pattern analyses and examining them from a longitudinal approach, open up potential opportunities to gain deeper insights into diet-disease relationships and support the development of more holistic lifestyle disease prevention recommendations stratified for population groups.