Are food and drink available in online and physical supermarkets the same? A comparison of product availability, price, price promotions and nutritional information

OBJECTIVE: Online supermarkets are increasingly used both by consumers and as a source of data on the food environment. We compared product availability, nutritional information, front-of-pack (FOP) labelling, price and price promotions for food and drink products between physical and online supermarkets.

DESIGN: For physical stores we collected data on price, price promotions, FOP nutrition labels and nutrition information from a random sample of food and drinks from six UK supermarkets. For online stores we used foodDB, a research-ready dataset of over 14 million observations of food and drink products available in online supermarkets.

SETTING: Six large supermarket stores located near Oxford, United Kingdom.

PARTICIPANTS: General sample with 295 food and drink products, plus boost samples for both fruit and vegetables, and alcohol.

RESULTS: In the general sample, 85% (95% confidence intervals, 80,90%) of products found in physical stores could be matched with an online product. Nutritional information found in the two settings was almost identical e.g. concordance correlation coefficient for energy = 0.995 (0.993,0.996). Presence of FOP labelling and price promotions differed between the two settings (Cohen's kappa = 0.56 (0.45, 0.66) and 0.40 (0.26, 0.55) respectively). Prices were similar between online and physical supermarkets (concordance correlation coefficient > 0.9 for all samples).

CONCLUSIONS: Product availability, nutritional information and prices sourced online for these 6 retailers is a good proxy of that found in physical stores. Price promotions and FOP labelling varies between the two settings. Further research should investigate whether this could impact on health inequalities.