Dietary trajectories over 21 years and frailty in Norwegian older adults: the Tromsø Study 1994-2016.

Purpose: To investigate the association between five dietary trajectories over 21 years and frailty in Norwegian older adults.

Methods: This study used data from three surveys of the Tromsø Study. Diet was measured using food frequency questionnaires at baseline (Tromsø4, 1994-95), after 7 years (Tromsø5, 2001) and at the end of follow-up (Tromsø7, 2015-16). Survey-specific diet scores were constructed based on the Nordic Nutrition Recommendations 2023 and group-based trajectory modelling was used to derive dietary trajectories. At follow-up, frailty was assessed with a 41-item frailty index. Linear regression analysis was performed to assess the associations between dietary trajectories and frailty, adjusted for baseline variables.

Results: Among the 715 participants, 55% were women, with an average age of 54 years at baseline and 74 years at follow-up. The dietary trajectories 'moderately healthy' and 'healthy increase' were associated with a lower frailty index score at follow-up (β = -0.02, 95% confidence interval (CI) = -0.04, -0.002, β = -0.03, 95% CI = -0.06, -0.007), compared with the 'unhealthy' trajectory.

Conclusion: Our findings suggest that maintaining a moderately healthy to very healthy diet from mid-life into older age is associated with a lower risk of frailty and supports the promotion of a healthy diet from adulthood to facilitate healthy ageing.