Spatial analysis of dietary cost patterns and implications for health

Background: Chronic diseases such as obesity, cardiovascular disease, diabetes and cancer are a large burden on society, for which diet is the leading modifiable risk factor. ‘Diet’ can encompass a variety of aspects of food consumption. Dietary patterns arguably best reflect food as consumed. The determinants of diet are varied and include cost and availability of foods. The aim of this research is to investigate if dietary patterns and diet cost vary spatially and whether this influences health outcomes, specifically obesity and breast cancer. Methods: Using data from the UKWomen’s Cohort Study, data driven dietary patterns were previously determined. Cost of diet was assigned using a food cost database. Spatial measures for Government Office Region, North South, Urban/ Rural and the Output Area Classification were assigned matched to postcode of the women.Weight status is calculated from self reported height and weight. Time to event analysis investigated association between dietary pattern, diet cost and breast cancer incidence at each spatial scale. Results: There is some spatial variation in dietary patterns both between and within regions. A healthy in more expensive per day than a less healthy one: £6.63 compared to £3.29. The overweight/ obese pay more for their food. Urban and Northern areas have significantly higher BMI than Rural and Southern areas respectively. Those in areas Constrained by Circumstance have highest prevalence of overweight and obesity. There is some spatial variation in breast cancer incidence and variation by dietary pattern. In postmenopausal women, positive association exists between weight status and risk of breast cancer incidence. Methods used for estimating small area dietary patterns and health outcomes may be applicable for use in other developed populations. Conclusion: Understanding determinants of dietary patterns remains important for public health and making healthy diets accessible to all is important. However, while expensive dietary patterns reflect a healthier diet, they do not appear to be the mechanism for which obesity prevalence and breast cancer incidence occur. Geodemographic classifications, combined with other spatial measures could aid more effective targeting of public health nutrition policy.