Interventions to reduce the saturated fat (SFA) content of food purchases may help reduce SFA consumption and lower cardiovascular risk. This factorial RCT aimed to examine the effect of altering the default order of foods and being offered a swap on the SFA content of food selected during an online shopping experiment.
UK adults who were the primary grocery shoppers for their household were recruited online and invited to select items in a custom-made experimental online supermarket using a 10-item shopping list. Participants were randomly allocated to one of four groups (i) to see products within a category ranked in ascending order of SFA content, (ii) receive an offer to swap to a product with less SFA, (iii) a combination of both interventions, or (iv) no intervention. The primary outcome was the difference in percentage energy from SFA in the shopping basket between any of the four groups. The outcome assessors and statistician were blinded to intervention allocation.
Altering the default order to show foods in ascending order of SFA and offering a swap with lower SFA reduced percentage energy from SFA in an experimental online supermarket. Environmental-level interventions, such as altering the default order, may be a more promising way to improve food purchasing than individual-level ones, such as offering swaps.
Food purchasing is a key determinant of food consumption and interventions targeting the nutritional quality of food during shopping present a clear opportunity for an intervention with wide reach. Individual-level interventions previously identified in systematic reviews as effective behaviour change techniques (e.g. tailored dietary advice, information, self-monitoring and personalised feedback) can be easily applied in the context of online supermarket shopping [7, 8]. A previous study recommending lower SFA options at the point of purchase showed a significant reduction in total SFA from online food purchases with no difference in expenditure .
The aim of this trial was to test the effectiveness of an environmental-level intervention (i.e. altering the default order of foods to show foods in ascending order of SFA) and an individual-level intervention (i.e. an explicit offer to swap to an alternative food with lower SFA) on the SFA content of online food shopping. In this proof-of concept trial, we used an experimental online research shopping platform to explore the effectiveness of these interventions, alone or in combination, compared to no intervention.
When searching or browsing foods, participants viewed a list of products in ascending order of SFA content (i.e. the products with the lowest SFA content appeared at the top of the screen) but this order was not made explicit to participants. Moreover, the SFA content of the food was not displayed in the product list but, in common with all UK online supermarkets, the SFA content along with other nutrients from the nutrient facts panel was shown if the participant clicked on a product in search of more information. The SFA order was applied to each list of foods offered to participants when searching for products. An example of the intervention is shown in Fig. 1b.
Investigators were not blinded to intervention allocation, but they were not able to manipulate any study parameter following the initial study set up, as all study procedures took place in the online platform. The outcome assessment was blinded, as it happened automatically in the online platform. The statistician was blinded to intervention allocation. Participants were necessarily unblinded and were aware of the study aims.
Altering the default order to show foods in ascending order of SFA and offering an explicit swap with lower SFA during an online shopping experience significantly reduced the percentage energy from SFA of the selected foods. Altering the default order was significantly more effective than offering swaps and there was no evidence that providing swaps in addition to altering the order augmented the effect of the intervention. There was no evidence that the intervention affected the expected cost of products selected.
This is the first randomised trial aiming to directly compare an environmental-level (altering the default order) and an individual-level (offering swaps) intervention and their combination for improving the nutrition quality of food purchases. A previous trial conducted in a real online supermarket testing swaps with lower SFA demonstrated a much smaller effect than observed in the current trial . However, their primary outcome was calculated as grams of SFA per total weight of foods in the total basket rather than as a percentage of energy. Whether any difference in effect size is due to the simulated versus real environments or due to differences in the shopping lists, the algorithm suggesting the swap, or the number of swaps accepted is unclear. Our interventions to reduce percentage energy from SFA also reduced the energy density of items selected. This is in contrast with a previous study using the same experimental platform which specifically offered swaps with lower energy density but found no effect of the intervention. This might be explained by the differences in the shopping lists, in the algorithm determining swaps, or the exclusion of energy dense cooking ingredients, such as butter, from their analysis . A previous systematic review of interventions to change food purchasing behaviours in grocery stores did not identify any other randomised controlled trials on the effect of altering the default order of foods . However, a recent trial showed no difference of altering the positioning of a specific category of foods (i.e. fruit and vegetable snacks) on the proportion of orders in an online school canteen ordering system. The discrepancy with our findings might be because that intervention was trying to make more prominent a category of food which people were not necessarily trying to buy, whereas we were trying to make certain foods more prominent within a specific category from which participants had been instructed to select an item .
There has been a sharp rise in the proportion of households purchasing groceries online, reaching 28% of UK consumers in 2017 from 4% a decade earlier, with similar upward trajectories being observed across Europe , East Asia , and the USA . This trial shows that offering swaps and altering the default order are potentially effective strategies to encourage healthier food purchasing. Real online supermarkets usually alter the position of foods for marketing purposes, but to our knowledge not for health purposes. A UK online supermarket is already implementing healthier swaps at checkout, but the algorithm is unpublished and a previous trial suggested higher acceptance of swaps at the point of selection than at checkout . In our study, there was some indication that swaps for cheese, butter, and sweets and desserts might have been more acceptable than those for milk or meat. Future research could examine whether swaps are more acceptable in certain product categories.
Future research should also aim to test these strategies using real online platforms and supermarkets and, contingent on their effect in the short term, study their long-term impact on food purchasing habits. In the meantime, online supermarkets should be encouraged to play a more proactive role in shaping heathier choices for their customers and can capitalise on the results of this study by offering either or both interventions knowing that they are potentially effective strategies for reducing percentage energy from SFA without increasing cost to their customers.
Strengths of this study include the randomised factorial design, blinded statistical analysis, high completion rate, precision of the estimate of the treatment effect, and the use of products typically present in real supermarkets in a convincing simulated grocery store website. Open text responses from a small number of participants at the end of the study implied that participants had fully engaged with the shopping experience.
In conclusion, altering the default order to show foods in ascending order of SFA and offering a swap with lower SFA reduced percentage energy from SFA in an experimental online supermarket. Environmental-level interventions, such as altering the default order, may be a more promising way to improve food purchasing than individual-level ones, such as offering swaps.
There is a report provided by ecommerceDB which points to the top 10 online supermarkets around the globe. Most people consider supermarkets as places where they physically go, push the trolley, and put things in, rather than online shopping and having them delivered, so this comparison is quite unique.
Nevertheless, online shopping for food and beverages is getting popular, especially since the pandemic forced us to turn on the online mode in many aspects of our lives. It is forecasted that by 2025 online sales will increase by 15-20% in this industry.
This online supermarket outclassed the rest. Tesco was founded in 1919 in the UK and over the years the chain expanded to e.g., Hungary, Slovakia or even Malaysia. Now, over a century later, its eCommerce net sales were 7,588.9 million dollars in 2020 and are expected to reach 10,826.3 million dollars by 2025. What is very interesting, almost 100% of its eCommerce net sales are generated by UK consumers.
The second place belongs to kroger.com. This supermarket was founded in 1883 in Ohio. What is worth mentioning, Kruger is the fourth-biggest employer in the States. Its eCommerce was launched in 2014 and as you can see it is still doing well!
Here comes the next UK player. The Sainsbury was founded in 1869 by John James Sainsbury. Over 150 years on the market has brought this supermarket a lot! For example, it conquered the digital world. In 2020, sainsbury.co.uk generated 3.6 billion USD.
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