It's an open secret that supermarkets play psychological tricks on us. One involves product placement: Fruits and vegetables, the meat counter and chiller cabinet are all positioned to entice us to put more items into our shopping trolleys.
In two recently published studies, researchers from the Nuffield Department of Primary Care Health Science at the University of Oxford in England examined whether such methods could be used to encourage sales of healthier foods over less healthy ones. Results turned out to be mixed.
The studies were done, write the researchers in the journal PLOS Medicine, because caloric intake from free sugars and saturated fat exceeds recommended levels across all age groups in the UK, where 26% of men, 29% of women and 20% of children aged 10 to 11 are said to be obese. As appeals to eat heathier have failed, authorities have said they would introduce legislation to restrict the promotion of foods high in these substances, and also salt, in prominent store locations.
In one of the studies, the researchers had free-standing promotional displays of seasonal chocolate confectionery removed from prominent areas (end of aisles and entrance) of 34 London grocery stores over seven weeks before Easter. The products were available elsewhere in the stores though. Data from the intervention stores were matched with those from 151 control stores elsewhere in the UK owned by the same large food retailer.
The study showed a marked attenuation of the seasonal increase in confectionery sales in intervention stores compared with control stores: in number of items (+5% versus +18%), weight (+12% versus +31%) and monetary value (−3% versus +10%). The absolute difference amounted to about 127 items (approximately 21 kg) of confectionery per store per week.
While the researchers report significant reductions in total calories and fat from all food-related purchases in stores implementing the intervention, there were no significant changes in saturated fat or total sugars.
On balance, however, the results "provide promising evidence that the proposed legislation in England to restrict promotions of less healthy items in prominent locations may help reduce overconsumption," they write.
In the other study, the research team examined six interventions in major UK supermarkets to see how availability, positioning, promotions and signage of healthier food options affected purchasing behaviour. When lower-fat frozen chips were stocked next to regular ones in intervention stores, for example, sales of the latter fell by 23%.
Increasing the availability of lower-calorie packs of biscuits increased their sales by 18%, but sales of regular biscuits fell by only 4%. And a nationwide promotion using Disney characters increased sales of no-sugar baked beans (+54%) and selected fruits (+305%), but only temporarily.
On the other hand, a price promotion on seasonal fruits and vegetables showed no evidence of increased sales in intervention versus control stores. Nor was there evidence that placing higher-fibre breakfast cereals at eye level increased their sales or reduced sales of regular cereal. And shelf labels to highlight low-sugar or sugar-free beverages showed no effect in changing purchasing behaviour.
According to the researchers, the results of their studies could be of interest to policymakers considering new ways to support healthier choices in supermarkets. "It is important to note that the interventions here focused on encouraging swaps from a less healthy to a healthier option or increasing overall sales of healthy foods, such as fruits and vegetables," they write.
"This is an attractive commercial proposition, but the impact of these interventions on the overall energy content of food purchases is likely to be considerably smaller than interventions that specifically seek to reduce impulse or discretionary purchases, such as the removal of foods high in fat, sugar, and salt from prominent locations such as end of aisles."
Indeed, another British study recently found that supermarket customers bought considerably fewer sweets when they weren't placed near the checkout counters at the end of the shopping route. And fruits and vegetables were selected more often when they were displayed in stores' entrance area.
