Neighbourhood walkability and dietary attributes: Effect modification by area-level socio-economic status

Objective: Higher neighbourhood walkability would be expected to contribute to better health, but the relevant evidence is inconsistent. This may be because residents' dietary attributes, which vary with socio-economic status (SES) and influence their health, can be related to walkability. We examined associations of walkability with dietary attributes, and potential effect modification by area-level SES. Design: The exposure variable of this cross-sectional study was neighbourhood walkability, calculated using residential density, intersection density, and destination density within 1-km street-network buffer around each participant's residence. The outcome variables were dietary patterns (Western; prudent; and mixed) and total dietary energy intake, derived from a food frequency questionnaire. Main and interaction effects with area-level SES were estimated using two-level linear regression models. Setting: Participants were from all states and territories in Australia. Participants: The analytical sample included 3,590 participants (54% women, age range 34 to 86). Results: Walkability was not associated with dietary attributes in the whole sample. However, we found interaction effects of walkability and area-level SES on Western diet scores (P<0.001) and total energy intake (P=0.012). In low SES areas, higher walkability was associated with higher Western dietary patterns (P=0.062) and higher total energy intake (P=0.066). In high SES areas, higher walkability was associated with lower Western diet scores (P=0.021) and lower total energy intake (P=0.058). Conclusions: Higher walkability may not be necessarily conducive to better health in socio-economically disadvantaged areas. Public health initiatives to enhance neighbourhood walkability need to consider food environments and socio-economic contexts.