Abstract:
Introduction The causes of obesity are multi-factorial and retail food environments which provide a greater availability of unhealthy versus healthy foods may be one factor. The community retail food environment is being increasingly investigated using Geographic Information Systems as a contemporary method for assessing the associations between food outlet geographies and diet-related health and/or area deprivation. This study was a spatial analysis of community retail food environments in New Zealand (NZ) and their associations with area deprivation. Methods Data on more than 20,000 registered food outlets were retrieved from Councils across NZ. This list was classified into 14 food retail categories and geocoded using a tool specifically developed for this study. The validation indicated that about 90% of outlets were correctly categorised and geocoded. Outlets were mapped using ArcMap 10.2 and measures of outlet density and proximity around/from meshblock centres and schools were stratified by quintiles of the NZ Deprivation Index (NZDep2013) or school deciles. Spatial Autocorrelation was used to identify potential food ‘deserts’ (low density of healthy outlets) or ‘swamps’ (high density of unhealthy outlets) adjusted for population densities. Results A threefold higher concentration of fast food outlets and takeaways was observed in the most deprived compared to the least deprived census areas of NZ (p<0.001). In addition, a positive association (p<0.001) was observed between all types of food retail proximity and area deprivation. There is evidence for food swamps in NZ, with 103 out of 1856 census area units showed significant clustering of ‘unhealthy’ food outlets. Concurrently, a significantly higher (p<0.01) density of unhealthy food sources (convenience stores, fast food and takeaways) was observed around lower decile schools in comparison to higher decile schools. Discussion The findings of this study of more food swamps in higher deprivation areas are in consensus with previous NZ and non-U.S. studies. For future monitoring of retail food environments in NZ, it is recommended that the current food retail recording practices of NZ Councils be improved. Policy implications resulting from this study include: the need for intersectoral policy developments; restriction of the number of obesogenic food outlets around schools as part of the creation of ‘green school food zones’.