Ads in shopping carts boost healthy purchases

La Trobe University research has found that using social norm nudges as prompts in supermarkets led to a cheap and effective way to increase purchase of these products crucial to our health—leading to an increase on average of 1.26 kg more fruit and vegetables purchased per shopping trip.

Published in the journal Nutrition Bulletin, the study looked at the efficacy of placards in carts giving the message that the majority of shoppers purchased fruit and vegetables at each shop.

The placards stated that "more than 9 out of 10 shoppers (at this grocery store) buy fruit or vegetables at each shop."

Dr. Greg McGrath, a graduate researcher in Public Health at La Trobe University, said supermarkets and grocery stores are significant food environments and one of the main sources of food purchases, comprising up to 68% of the retail food market share in Australia.

"Consequently, supermarkets and grocery stores hold a significant position and power and regularly implement a variety of marketing strategies to influence shopper food purchasing. These same strategies can be used to influence healthy eating," Dr. McGrath said.

Thirty percent of carts in a major Melbourne grocery store were fitted with the placards and shopper purchases were measured by collecting receipts to measure the quantity and cost of fruit and vegetables purchased. The researchers also surveyed the shoppers as they exited the store.

Shoppers who selected carts with the social norm nudge placards purchased 1.25 kg more fruit and vegetables and spent an extra $9.10 more on these items compared to shoppers in the control group.

Dr. McGrath said the study suggested that social norm nudge placard show promise in modifying shoppers' purchases.

"It's a simple and relatively cost free way to subtly push shoppers to buy healthier food," Dr. McGrath said. "These social norm nudges show potential in tackling chronic diseases such as obesity, type 2 diabetes and cardiovascular disease."