One of the most recurrent New Year’s resolutions is to lose weight. Nevertheless, year after year only very few of us achieve this noble objective despite our good intentions. As a result, obesity and overweight have not been declining. Clearly, this is a complicated subject and many factors can be attributed to why it is not as easy to lose weight as it is to gain it. Earlier, it has been highlighted how obesogenic environments coupled with our human/psychological flaws undermine our plans to maintain a healthy body weight. In a recent systematic review published in BMC Public Health, we considered one important environmental factor that plays a major role in calories consumed: the food store. We surveyed and then evaluated health interventions aiming to promote healthy food purchase behavior at food stores and among targeted populations. We assessed not only the effectiveness of various strategies, but we also put the methodological quality of the addressed studies to test. Following is a summary of the main findings from our review.
What characterizes effective food store health interventions?
The general finding of our review is the efficacy of in-store/point-of-purchase healthy food interventions, despite some articles with low methodological quality. Furthermore, the effectiveness of food store health interventions depends on several factors including the type and number of intervention components, employed incentive structure for participating store owners as well as targeted population of consumers, stakeholder involvement and approval, community/consumer engagement, and depth of intervention implementation.
Interventions with multiple strategies are to be preferred as they complement each other. In addition, we found that price incentives receive the strongest response in terms of outcome. This holds true for direct price discounts, vouchers for healthy foods, and subsidies of certain nutritious foods. Incentives work not only for consumers, but also for participating food stores. Example of successful incentives for food stores include the Women, Infants and Children (WIC) program in the United States, which incentivizes eligible stores to stock certain promoted healthy foods, and a national discount program in South Africa (Vitality HealthyFood program) that targets households who are members of an insurance company and offers them a discount of up to 25% on healthier foods at more than 800 supermarkets throughout the country. Due to their large scale, both these programs create incentives for supermarkets as well as targeted consumer groups to show pro-health behavior. It should be noted that stores could also be brought on board by incentives other than monetary. Some stores may be interested in building their reputation and as such they can be convinced to promote pro-health food stocking strategies as part of their corporate social responsibility.
Moreover, engaging consumers and creating an interactive environment for them, in addition to posters and shelf labels, seems to be more helpful than mere labels or nutrition information. Examples of successful consumer engagement include cooking demonstrations/taste tests, and interactive education.
What could be improved in the future?
With regards to research quality, we found that, according to the chosen assessment tool, the methodological quality scores of the papers range from the lowest score of 42.9% to the highest score of 92.9%, yielding an average quality score for all papers of 65.0%. A major takeaway from this result is the need for more high quality studies. Unlike other settings, such as studies reporting school-based interventions, the number of randomized controlled trials (RCTs) is limited for food store settings, albeit with encouraging progress recently. Therefore, more high quality studies in the form of RCTs are called for.
Although price interventions have the strongest impact on the outcome of healthful food purchase, we note, however, important observations. It is not trivial to implement price incentives on a large scale and for sustained periods. Therefore, it needs more persuasion than other interventions (such as information campaigns) as someone has to bear costs associated with subsidizing healthier foods (or higher prices for less healthier foods). The difficulty is even more pronounced if their implementation is not cost-neutral, as someone has to finance the difference due to changes in the original prices. In certain cases, storeowners may be convinced that, due to economies of scale, they will not incur losses despite price reductions of healthier foods. In most cases sustained price interventions need political solutions, and as such research should be disseminated in a way that motivates political action.
A related observation when conducting this review is the limited number of studies that use the currently influential concept of nudging which is believed to be a low-cost alternative to other intervention approaches. For example, few studies demonstrate the effect of using shelf space management to promote healthy foods in prime in-store locations. It is particularly interesting as some prime locations like the checkout area are currently used for promoting high calorie foods. Therefore, more experiments with nudging and other innovative intervention methods in grocery settings are needed.
Furthermore, more focus should be given to both healthy and unhealthy foods and substitution behavior. The majority of current interventions focus on F&V as the promoted healthy food. While these interventions are rightly justified as most people in many countries do not meet F&V dietary guidelines, there is also a need to consider interventions to limit the consumption of less healthy foods, e.g. high energy items such as sugar sweetened beverages (SSB) and salty snacks. If possible, total food store sales should be used to judge the overall effect of the intervention (including substitution effects). Although differences in studies are unavoidable and understandable, adopting some common outcome measures would be useful to enhance comparability of studies. Moreover, food frequency questionnaires used in some studies, if possible, should be supplemented with objective sales data.
Finally, our findings also highlight the challenges involved with in-store healthy food interventions. We cannot stress enough the importance of stakeholder management and the use of correct incentives for these agents, particularly the food stores whose support is critical for any effort in this direction. It is important to show store managers how their stores can benefit from the proposed intervention, and not just present them with how the intervention benefits research or even the target group. Show them what is in it for them.