Neighbourhood exposure to fast-food and sit-down restaurants and estimated 24-hour urinary sodium excretion: A cross-sectional analysis of urban adults from the ORISCAV-LUX 2 study

OBJECTIVE: Increased out-of-home consumption may elevate sodium (Na) intake, but self-reported dietary assessments limit evidence. This study explored associations between neighbourhood exposure to fast-food and sit-down restaurants and estimated 24-hour urinary Na excretion.

DESIGN: A cross-sectional analysis from the ORISCAV-LUX 2 study (2016-2017). 24-hour urinary Na was estimated from a morning spot urine sample using the INTERSALT formula. Spatial access to fast-food and sit-down restaurants was derived from GIS data around participants' addresses within 800-m and 1000-meter road-network buffers by summing up the inverse of the road-network distance between their residential address and all restaurants within the corresponding buffer size. Multi-adjusted linear models were used to assess the association between spatial access to restaurants and estimated 24-hour urinary Na excretion.

SETTING: Luxembourg.

PARTICIPANTS: Urban adults age over 18 years (n=464).

RESULTS: Fast-food and sit-down restaurants accounted for 58.5% of total food outlets. Mean 24-hour urinary Na excretion was 3564 mg/d for men and 2493 mg/d for women. Health-conscious eating habits moderated associations between spatial access to fast-food and sit-down restaurants and Na excretion. For participants who did not attach great importance to having a balanced diet, greater spatial access to restaurants, combining both density and accessibility, was associated with increased urinary Na excretion at 800 m (β highvslow = 259, 95% CI: 47-488) and 1000 m (β highvslow = 270, 95% CI: 21-520).

CONCLUSIONS: Neighbourhood exposure to fast-food and sit-down restaurants influences sodium intake, especially among individuals with less health-conscious eating habits, potentially exacerbating diet-related health disparities.