Evaluation of two social norms nudge interventions to promote healthier food choices in a Canadian grocery store | BMC Public Health

Fruit and vegetable consumption in children is an important contributor to achieving and maintaining a healthy body weight. A diet rich in fruits and vegetables is also protective against many chronic diseases such as cardiovascular disease, type 2 diabetes, and cancer [1]. Canada’s Food Guide (CFG) encourages individuals of all ages to include plenty of fruits and vegetables in meals and snacks (four to eight servings a day for children and seven to ten servings a day for adults (age and sex dependent) [2]. Despite this recommendation, just 20.7% of the Canadian population ages one and older met or exceeded CFG recommendations for daily fruit and vegetable consumption [3]. Youth-specific research has reported adherence to these recommendations to be as low as one in ten Canadian children [4].

Healthy eating is an individual behavior but there are many internal and external factors – eg, biological, psychological, cultural, and social factors, as well as community and policy settings – that influence food choices [5]. Effective health promotion and childhood obesity prevention efforts must extend beyond a single sector and involve the whole-of-community so children and families see consistent messaging and are supported in making healthy choices where they live, learn, and play [6].

Sustainable Childhood Obesity Prevention through Community Engagement (SCOPE) is a community-based participatory research project in the province of British Columbia (BC), Canada. SCOPE developed Live 5–2-1–0, a ​​multi-sectoral, multi-component childhood obesity prevention initiative centered on the evidence-based 5–2-1–0 message (ie, five or more portions of vegetables and fruits, < two hours of recreational screen time, at least one hour of physical activity, and zero sugary drinks per day) [7, 8]. Using a collective impact approach, SCOPE partners with communities across BC to engage a range of community stakeholders (eg, in local government, health, education, business) to share the Live 5–2-1–0 message and create healthier environments for children and families [7, 8].

Businesses are an integral part of a community and play an influential role in the health behavior choices that are available, as well as the healthy messaging that is relayed to local residents. Grocery stores are one private sector setting where health promotion initiatives aimed at increasing fruit and vegetable intake can be mutually beneficial to both the patron (improving customers’ food choices) and the business (potential profitability of increased produce sales, a high margin product category) [9]. However, to date, grocery store interventions aimed at promoting healthy food choices through education and environmental changes have had mixed outcomes and have been mildly successful at best. [10, 11]. For example, point-of-purchase interventions (eg, interactive displays and brochures) alone were deemed ineffective in a systematic review of grocery store interventions, while studies that combined point-of-purchase interventions with changes to pricing, the availability of healthy food , promotion, and advertising showed stronger effect on promoting healthy food choices [10].

There is growing evidence of the effectiveness of interventions that utilize ‘nudges’ – a nudge aims to alter an individual’s behavior in a predictable way without restricting one’s options when making decisions [9, 12,13,14,15,16]. Nudge interventions are based on dual-process models of behavior which posit that behaviors result from the interaction of both an unconscious, automatic mode of processing (System I), and a conscious, slow, rational mode of processing (System II) [17]. Nudge interventions utilize heuristics to influence the automatic/System I mode of processing and decision-making. Grocery store nudge interventions may also leverage the social aspects of grocery shopping such as shoppers’ perceptions of what foods are common, normal or appropriate to purchase [18]. Examples of nudges in this setting include highlighting items using focused lighting, mounting shelf labels that advertise promoted items, and improving accessibility of products through product placement [9, 19, 20].

One nudge-based intervention that has demonstrated effectiveness in increasing fruit and vegetable purchases in supermarkets is the installation of partitions in grocery carts to designate a section for ‘fruits and vegetables’, thereby emphasizing social appropriateness of purchasing fresh produce [18]. Huitink et al. [18] showed that an inlay in grocery carts with messages about the vegetable purchases of other customers, and an allocated grocery cart partition for vegetables, resulted in a statistically significant increase in grams of vegetables purchased (900 g to 1120 g on intervention days). More recent work in Portugal exposed shoppers to a social norm message suggesting the healthiest families purchase 11 fruits and vegetables on each visit to the store. The researchers found that shoppers with the least healthy purchasing behaviors prior to the intervention were positively impacted by this intervention and increased the number of fruit and vegetables they bought.

Canada’s geography may play a role in access to healthy foods, especially for rural and remote communities [21, 22]. Nudge interventions may represent a mutually beneficial activity for grocery stores to support a community driven, collective approach to health promotion while increasing produce sales. However, grocery nudge interventions have not been explored extensively within the context of remote, locally owned grocery stores in Canada. This represents a significant gap in the literature as available evidence suggests rural residence may be a risk factor for having a poorer diet due to limited availability and higher prices for fresh produce. [23, 24]. The objective of this study was to address this knowledge gap by using up-to-date data to determine the impact of two evidence-based nudge interventions on customers’ purchasing patterns and produce sales at a grocery store located within a rural Canadian community.

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