Background: Stability in dietary habits has been observed during childhood and adolescence, but their stability from infancy to adulthood is less known.

Objectives: Our aim was to identify latent diet quality trajectories from age 1 to 18 y and to examine their association with diet quality at age 26 y.

Methods: The study included 620 participants from the Special Turku Coronary Risk Factor Intervention Project, initiated in infancy. Food and nutrient intake were assessed annually from age 1 to 18 y and again at age 26 y using food records. A food-based diet score (range: 0-33) was calculated to indicate diet quality. Group-based modeling was used to model trajectories of diet quality between the ages of 1 and 18 y. Logistic regression analysis examined associations of childhood sociodemographic characteristics with diet trajectories. Linear regression analyses investigated associations between the observed developmental diet quality trajectory groups and diet quality at age 26 y, adjusted for adulthood sociodemographic characteristics.

Results: From age 1 to 18 y, 5 diet quality trajectory groups were identified: low (19% of participants), decreasing (25%), increasing (15%), intermediate (31%), and high (10%). Throughout the follow-up period, the diet score remained at 20-22 in the high diet quality trajectory group and at 11-13 in the low diet quality trajectory group. The diet quality trajectory groups predicted diet quality at age 26 y (P < 0.001). The adjusted mean difference in adulthood diet score between the low and high diet trajectory groups was 3.6 (95% CI: 1.5, 5.7). Notably, participants in the intervention group had higher scores than controls across all trajectories and throughout the entire follow-up period.

Conclusions: The 5 distinct diet quality trajectory groups from infancy to adulthood highlight a clear difference between the highest and lowest diet quality groups. The findings suggest that dietary habits established in early childhood remain moderately stable into early adulthood.