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Climate-friendly shopping tops led to more sustainable and healthier purchases

Shoppers offered climate-friendly grocery swaps in a simulated online store lowered their carbon footprint and purchased healthier foods.

In a randomised trial, published in the PLOS Medicine journal, 1,201 US participants visited a simulated online grocery store designed to mirror the look and feel of a real store – it contained over 5,000 products and six departments.

At a glance:

• On average, shoppers accepted one in four swaps, and spent between $1.40 and $2.30 less per visit.
• Shoppers perceived lower-carbon products as more healthful but did not consider healthier products as lower-carbon.
• Swaps offered to shoppers were not price-matched, which leaves cost as an untested factor.

Participants were assigned to one of four groups – climate swaps; health swaps; climate and health swaps; and control. They visited the simulated store on three separate occasions, were given $50 per trip, and asked to shop as they usually would.

Every grocery item had a colour code – from A to F – aligned to the three conditions. When a participant chose an item with a code from C to F, they were offered a higher-rated alternative.

In all three conditions, shoppers made healthier choices compared to the control. Those in the health swap condition made the highest number of healthy swaps, while those in the climate and the climate + health swap condition were the only ones to reduce the carbon footprint of their baskets.

“Many consumers want to eat more healthfully and make choices that are better for the environment,” Anna Grummon, director of the Stanford Food Policy Lab and lead author of the study, told Ingredients Network.

“Our study shows that even small changes, such as swapping just a few products for similar alternatives, can add up to meaningful improvements in the overall healthfulness and environmental impact of our food purchases,” she added.

Climate-related messaging might encourage people to buy healthier foods

The healthiness of baskets was scored using the Ofcom Nutrient Profiling model – which was converted to a 1-100 scale, where a higher score is healthier.

In the climate swap condition, the healthiness of baskets improved by 2.4 points, and carbon footprints were cut by 3.3 kilograms CO₂-eq per kg – which refers to the kilos of carbon dioxide equivalent emitted for every kilogram of a physical product produced.

The healthiness of baskets in the health swap condition improved by 4.7 points, while carbon footprints were cut by only 0.4 CO₂-eq per kg, which the authors concluded was not a real difference.

Although the health swap group did not reduce the overall carbon footprint, the authors did note that “they reduced the carbon footprint of milk and dairy selections and sweets and snacks selections”.

Participants in the climate + health swap condition improved both the healthiness of baskets (4.0 points) and cut carbon footprints (2.8 CO₂-eq per kg).

“The climate swaps also led participants to think more about health while shopping, while the health swaps did not increase thinking about climate impact,” the authors wrote.

They suggested that the results point to “asymmetric halo effects,” in which consumers perceive products with lower carbon impacts as more healthful, but do not consider a more healthful product to have a lower impact on the climate.

“Survey responses showed that the lower-climate-impact swap recommendations prompted participants to think more about health while they were shopping. This suggests that climate-related messaging might encourage people to buy healthier foods, even when health is not mentioned,” Grummon explained.

Retailers could tailor recommendations to consumers’ purchase history

Participants in the climate condition accepted around 25% of the swaps offered, while those in the health and the climate + health condition both accepted approximately 27%.

When asked if any strategies could lead to a higher number of swaps, Grummon said there may well be ways to encourage consumers to accept more swap recommendations.

“For example, retailers could try out different messages to accompany the swap recommendations or could try tailoring the recommendations based on a consumer’s purchase history,” she added.

Swaps were offered in around 20-30% of selections, given that these were choices that contained a C, D, or F grade.

“These results suggest that health and climate labels alone may have encouraged participants to select healthful or low-climate-impact items even before they were offered swaps,” the authors wrote. “However, because labels and swaps were always delivered together in our study, we cannot disentangle their independent effects.”

What are the key takeaways for consumers and retailers?

Total spending for all three groups was reduced, with baskets coming in between $1.40 and $2.30 less per trip.

The caveat is that the swaps offered to shoppers were not price-matched.

When asked whether shoppers would likely make the same decisions if the swaps offered cost more, Grummon said: “We know that consumers care about cost, especially given rising grocery prices.

“This suggests that consumers might be more likely to accept a swap recommendation if the suggested product is cheaper than the one they selected originally, but we did not test this in our study.”

As for the applicability of these results in the real world, Grummon had key takeaways for both consumers and retailers.

For consumers, Grummon highlighted how small changes, such as swapping a few products for those that are healthier or have a lower impact on the climate, can add up in the long run.

And for retailers looking to help their customers make healthier or more sustainable choices, she said that these types of swap recommendations may be a promising tool.