# Diet Quality Trajectories and Musculoskeletal Health Among the Oldest Old: Findings from the Hertfordshire Cohort Study

## TL;DR

This study explores how diet quality changes with age and its link to musculoskeletal health in older adults.

## Contribution

It identifies diet quality trajectories and their weak associations with musculoskeletal outcomes in the oldest old.

## Key findings

- Diet quality showed moderate stability over time with three distinct trajectory groups identified.
- Higher diet quality was associated with increased odds of hip/knee replacement but not other musculoskeletal outcomes.
- Poorer diet quality patterns around age 65 are likely to persist into old age.

## Abstract

Background: Few studies have examined changes in diet quality into old age, and related these changes to musculoskeletal outcomes. We examined this among Hertfordshire Cohort Study participants. Methods: In total, 178 individuals provided diet quality scores derived in 1998–2004, 2011 and 2017 (median age 64.0, 74.7 and 80.7) using principal component analysis of food frequency questionnaires; higher scores indicated healthier diets (more fruit and vegetables, oily fish and wholemeal bread, and less white bread, added sugar, full-fat dairy products, chips and processed meat). Pearson correlations between diet quality scores at each time-point were computed. Group-based trajectory modelling of diet quality scores was implemented; trajectory groups as predictors of musculoskeletal outcomes (history of hip/knee replacement, osteoporosis, fall in previous year, low grip strength, low gait speed) in 2017 were examined using logistic regression with age and sex included as covariates. Results: Diet quality showed moderate stability over time (0.64 < r < 0.74). Three trajectory groups were identified: low (29%), medium (51%), and high diet quality (20%). A higher diet quality group was related to greater odds (95% CI) of hip/knee replacement (1.85 (1.05, 3.26) per higher category); associations with other musculoskeletal outcomes were weak (p > 0.17). Conclusions: Weak associations were observed between diet quality trajectories and musculoskeletal outcomes. However, higher diet quality was related to increased likelihood of hip/knee joint replacement, potentially due to confounding by socioeconomic position. The stability of diet quality suggests individuals with poorer diets around age 65 are likely to maintain these patterns into old age and may benefit from targeted interventions.