‘Food deserts’ mapped across London using grocery shopping data

By Stephen Beech

Records levels of "food deserts" have been identified in London by analysing grocery shopping habits of more than 1.5 million people.

Tesco loyalty-card data revealed unequal sales levels of nutritious food across the city.

The new study identified "large clusters" of food deserts - area with limited access to affordable, healthy food, such as fresh fruit and veg.

They were mostly located in east London - particularly in the boroughs of Newham, Redbridge, plus Barking and Dagenham - and in parts of west London, including Ealing and Brent.

Poor diet and unequal access to healthy food are linked to rising rates of obesity, diabetes, and heart disease.

To effectively target interventions to areas where residents face barriers to accessing healthy food, scientists say identifying food deserts is necessary.

For the new study, published in the journal PLOS Complex Systems, researchers used the Tesco Grocery 1.0 dataset, a record of 420 million food items purchased by 1.6 million Tesco Clubcard holders who shopped at 411 Tesco grocery stores across London in 2015.

Transactions were linked to geographic areas of the residential address associated with the Tesco account, but were otherwise anonymised.

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The study revealed "distinct" geographic areas where residents bought more high-sugar, high-carb and processed foods and less fresh, high-fibre and high-protein options.

Inner north-west boroughs had the most nutritious purchase trends, while those in east London and the western boroughs had the least nutritious shopping records.

The research team developed a statistical model to analyze what factors could predict the food desert areas, and found correlations that varied by region.

In the east and west of London, higher income was associated with nutrient-deficient purchases, while it was associated with more nutritious purchases in the inner-west.

More car ownership was associated with more nutritious purchases in a small region of London’s north-west, but with nutrient-deficient purchases in the east, west, and north-west.

Higher proportions of black, Asian, and minority ethnic residents were associated with nutrient-deficient purchases in the west, northeast and inner-east food deserts.

Overall, the researchers say their model explained much of London’s variation in food buying, highlighting areas most at risk of nutrient-deficient food purchases.

Study leader Tayla Broadbridge said: “Our findings demonstrate the potential of analysing food purchase data to identify food deserts and their drivers, and suggest that area-specific, context-sensitive interventions are necessary for the implementation of local public health strategies."

Ms Broadbridge a joint-PhD candidate in mathematics at the University of Adelaide and the University of Nottingham, added: “We are rethinking food deserts: purchase data, not supermarket locations, shows the reality of access to healthy food in London.

“A map of stores only shows potential access - our data shows reality, revealing where Londoners’ diets are nutritionally deficient.”