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

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

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.

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.

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.