Food store accessibility affects nutritional intake through shopping frequency and food intake in middle-aged to older adults in rural Nagasaki, Japan

Objectives The food environment is an important determinant of dietary and nutritional intake, but studies thus far have reported mixed results. We examined associations between food store accessibility and nutritional intake among middle-aged to older adults in rural Japan using data from a questionnaire survey of national health insurance enrollees. Methods The survey was conducted in Nagasaki, Japan, for individuals aged 40-74 years. Direct distances from home and food store density were estimated using a geographic information system (GIS). We focused on protein, vitamin D, and calcium intake for their preventive effects on frailty and sarcopenia. To examine the effects of food store accessibility on nutritional intake, we hypothesized a model with a chain of associations of food store accessibility, shopping frequency, food intake frequency, and nutritional intake. We performed a path analyses to explore the food items to be included in the models, associations between the variables, and fitness of the models. Results We obtained final models with satisfactory fit indices. The resultant models included significant associations between: 1) accessibility indicators and shopping frequency, 2) shopping frequency and intake frequency for two or four categories of food, and 3) intake frequency and nutritional intake. Conclusions The results demonstrated that accessibility to food stores, assessed in terms of direct distance from home and food store density, can affect the intake of protein, vitamin D, and calcium through the effect on shopping frequency and intake frequency of some categories of food items, among middle-aged to older adults in Nagasaki, Japan.