There is increasing evidence that the food environment is an important determinant of dietary behaviour and obesity [1, 2]. With obesity accounting for almost 21% of health care costs in the US  and the UK’s NHS spending more than £5 billion a year on obesity-related health problems , governments are exploring policy options that modify the food environment to make healthier choices easier for consumers [5, 6].
Glanz et al.  have developed a conceptual model to guide food environment research. The focal points of the model are the four types of food environments: community nutrition environment, consumer nutrition environment, organisational nutrition environment and information environment. The majority of food environment research has focused on the community nutrition environment , which measures the number, type, location and accessibility of food sources . Fewer studies have assessed the consumer nutrition environment  which considers factors that influence food choice within stores such as availability, price, promotions, placement, variety, quality and nutrition information .
Assessment of the consumer nutrition environment in retail food stores is important because of the global convergence of shopping habits away from smaller specialty stores towards stores that stock a wider range of products . Consumer’s dietary choices are affected by the products sold, prices charged and promotional strategies used in their main food stores . More healthful food store environments could be defined as those which promote healthful food choices such as selling good quality healthy foods or placing them in prominent locations to prompt purchasing.
A number of tools to assess the consumer nutrition environment have been developed [11, 12], with the vast majority for use in the United States (US). Few tools have undergone reliability or validity testing or provide the level of detail required to assess linkages between retail food environments and dietary behaviour [11, 13, 14]. A great proportion of tools measure two in-store factors: availability and price [11, 12, 15]. A smaller number of tools have assessed variety and/or quality of fruit and vegetables [16–18], in-store advertising and/or product placement [13, 19, 20] or price promotions and nutrition labelling .
Some tools enable the creation of a composite score of the in-store environment including the widely used Nutrition Environment Measures Survey–Stores (NEMS-S)  and the CX
Food Availability and Marketing Survey ; both developed for the US context. The NEMS-S scores and CX
store scores incorporate three in-store factors: availability of healthier products, fruit and vegetable quality, and price or in-store advertising. The Health Responsibility Index was developed to measure the in-store environment of nine supermarkets in the UK . It measured sodium content, nutrition labelling and information, and price promotions on twelve frequently consumed processed products known to be high in sodium. Composite scores incorporating several consumer nutrition environment factors can provide an overall evaluation of the store environment and have been shown to help communities and policy makers in the US identify priority areas and inform interventions . However, no score has included more than three in-store factors or included standardised measures that can be used to statistically assess relationships between diet and in-store environments or monitor relative change in environment over time.
There is a gap in the literature for a comprehensive tool that measures multiple in-store factors concurrently on healthy and less healthy products, particularly outside the US. Such a tool could provide a thorough evaluation of differences in the retail food store environment by store type and neighbourhood deprivation and may identify target sites for interventions.
In the literature, supermarkets are portrayed as offering the healthiest shopping environment for consumers and small convenience stores the poorest [22, 23]. These broad categories however, cover a heterogeneous group of stores [10, 24]. In the UK for example, there are four different types of supermarkets that target different consumer groups [9, 10] and are likely to offer different shopping environments. Research that excludes the full range of environmental exposures or measures only healthy or less healthy foods may be misrepresenting the food environment within these stores.
Area based differences in the consumer nutrition environment have been observed in the US but no clear trend has been seen in other high income countries [25, 26]. In-store assessments based on a limited number of environmental factors and foods may be missing important socio-economic differences. An observation tool that evaluates several environmental exposures of foods commonly used to assess dietary disparities may provide a more complete environmental assessment.
This study addresses a current gap in the literature by developing a comprehensive consumer nutrition environment observational tool to measure the ‘healthfulness’ of food retail stores in the UK and testing differences by store type and neighbourhood deprivation.