https://orcid.org/0000-0001-9000-7692
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Abstract
Increasing consumer demand for organic foods and beverages is critical to boost sustainable agricultural production. Marketing interventions can be an effective way of influencing consumer preferences, but little is known about the effectiveness of these interventions at increasing demand for organic foods and beverages. This review synthesises recent evidence from studies evaluating real-world marketing interventions that aim to increase consumer demand for organic foods and beverages. Five databases were systematically searched and 18,743 titles and abstracts were screened against eligibility criteria. 21 studies covering 29 marketing interventions were included and assessed for risk of bias using the Evidence Project risk of bias tool. We found that price premiums had negative or no effects on overall consumer demand, although a subset of customers were willing to pay higher prices. Price promotions had mixed effects depending on product and customer type. Some place-based interventions–such as arranging organic products in a cluster and ensuring ready availability of these products–had positive and statistically significant impacts on consumer demand. Some promotional interventions–such as including organic messaging near product displays and securing newspaper coverage–were generally effective at increasing consumer demand. Ultimately, the effectiveness of these interventions differed across product categories, message framing, and the type of store and customer, necessitating strategic targeting of organic marketing interventions to promote more sustainable consumption.
Author summary
Organic agriculture has many benefits over conventional agriculture, from protecting biodiversity to promoting public health by reducing exposure to harmful chemicals. As a result, many countries are now setting targets for organic production. However, consumer demand for organic products lags behind. Increasing consumer demand for organic foods and beverages is critical in order to boost organic production. Marketing interventions can be an effective way of influencing consumer preferences, but little is known about how effective these types of interventions are at increasing demand for organic foods and beverages. We summarised recent evidence on the effectiveness of marketing interventions at increasing demand for organic foods and beverages. We found that price premiums had negative or no effects on consumer demand, although a subset of consumers were willing to pay higher prices. Price promotions had mixed effects depending on product and customer type. Some place-based interventions–such as placing organic products together in one part of the store–had positive impacts on consumer demand. Some promotional interventions–such as including organic messaging near product displays and newspaper coverage–were effective at increasing consumer demand. Effectiveness differed across the type of product, store and customer, suggesting that organic marketing interventions need to be targeted strategically in order to promote more sustainable consumption.
Citation: Sadler A, Moran D, Jaacks L (2024) Effectiveness of real-world marketing of organic foods and beverages: A systematic review of recent evidence. PLOS Sustain Transform 3(8): e0000123. https://doi.org/10.1371/journal.pstr.0000123
Editor: Abiodun Olusola Omotayo, North-West University Potchefstroom Campus: North-West University, SOUTH AFRICA
Received: December 5, 2022; Accepted: July 25, 2024; Published: August 19, 2024
Copyright: © 2024 Sadler et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the paper and its Supporting Information files.
Funding: AS was supported by a studentship from the Natural Environment Research Council. DM acknowledges funding from UKRI under grant numbers BB/W018152/1 and BB/T004436/1. LMJ was supported by a Future Leaders Fellowship from UKRI (Grant Ref: MR/T044527/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
1. Introduction
Sustainable agricultural production and consumption is growing in response to the detrimental consequences of conventional, synthetic chemical-based agriculture. Organic farming is a subset of sustainable agriculture that aims to produce agricultural commodities without the use of synthetic chemicals. Alongside a growth in organic production, the global market for organic foods and beverages has expanded from €15.1 billion in 2001 to €106.4 billion in 2019, with sales concentrated particularly in North America and the EU [1]. Despite this growth, organic foods and beverages remain only a small share of the total food and beverage market [2]. For example, in Denmark, which is considered the global leader in organic consumption, organics only comprise 12.1% of total food and beverage sales [1].
Expanding the organic sector depends on growth in consumer demand. Consumer demand can be defined in various ways, but in this study refers to having: (a) a positive attitude towards organic foods and beverages, (b) an intent to choose or purchase organic foods and beverages, and/or (c) actual purchases or consumption of organic foods and beverages. Studies have shown that a variety of factors drive consumer demand [3–8], with Katt and Meixner [4] classifying these factors as consumer-related (e.g., demographics, values and attitudes, behaviour), product-related (e.g., product attributes and signalling), and purchasing-venue related. Marketing initiatives can play a crucial role in increasing consumer demand for organic products through targeting consumer attitudes and purchasing behaviours, while also addressing product- and purchasing venue-related factors.
McCarthy [9] defined a conceptual framework for marketing known as the ‘four P’s’: product, price, place, and promotion. The ‘product’ category entails aspects related to the quality, value and features of the product, as well as its branding and packaging. For example, putting the EU or US Department of Agriculture (USDA) organic logos on products. ‘Price’ encompasses both the initial pricing strategy, such as a price premium, as well as discount incentives to encourage purchasing. ‘Place’ refers to where the products are sold (both digitally and in physical stores), and to product placement within those spaces; for example, having a separate section in supermarkets for organic products. ‘Promotion’ refers to the messaging and communications strategies employed to raise awareness and improve perceptions of the product, encompassing partnerships and sponsorships, as well as differentiated advertising strategies, ranging from word-of-mouth, to traditional media (television, radio, print), and ‘new media’ (webpage promotions, social media, emails, texts, apps) [10]. This systematic review included marketing activities related to each of the four P’s.
Existing systematic reviews have explored aspects of marketing for organic foods and beverages. Bastounis et al. [11], for example, evaluated product and price attributes, finding that eco-labels (including organic) increased consumers’ willingness to pay for eco-labelled foods. They found that consumers were willing to pay a price premium of 3.79 PPP$/kg (purchasing power parity) for eco-labelled foods, with hypothetical willingness to pay being higher for organics than other ecolabels; however, the experiments were all conducted in hypothetical laboratory settings [11]. Other systematic reviews have similarly included studies of experimental marketing interventions conducted in laboratory settings [4,7,11,12]. Nonetheless, there is often substantial divergence between consumers’ reported behaviours in a laboratory setting and their actual behaviour in response to real-world stimuli [13–15]. To date, there has been no systematic review of real-world price-based interventions and their impact on organic food and beverage demand. By ‘real-world’, we refer to actual interventions as opposed to hypothetical evidence.
This systematic review synthesised the evidence from studies evaluating real-world marketing interventions that aimed to increase consumer demand for organic foods and beverages. The second aim was to identify characteristics of effective interventions. The intervention refers to exposure to any real-world marketing that aims to increase demand for organic foods and beverages. ‘Marketing’ can encompass any of the ‘four P’s’ framework outlined by McCarthy [9]. The primary outcome was consumer demand (i.e., attitudes, intention to purchase, and/or actual purchases or consumption) for organic foods and beverages. The detailed methodology for this systematic review is outlined in section 2; we then summarise the results (section 3) and discuss their relevance to the broader literature (section 4), concluding with the wider implications of our study (section 5).
2. Methods
2.1. Protocol and registration
A protocol for this systematic review was published on OSF Registries [16] under the registration DOI: 10.17605/OSF.IO/KBZRM. Since the registration of the protocol, the risk of bias tool has been changed from ROBINS-I [17], which is more suitable to health-related interventions, to the Evidence Project risk of bias tool [18], which is more versatile.
2.2. Eligibility criteria
Empirical studies of real-world marketing initiatives that aimed to increase consumer demand for organic foods and beverages were included. Studies of consumer demand were defined as those that evaluated consumer attitudes, intent to purchase, and actual purchases or consumption. Actual purchases or consumption can be considered as indicating consumers’ ‘revealed preference,’ as opposed to ‘stated preferences,’ which are identified through hypothetical experiments [19]. Although price elasticity studies are based on actual purchasing data, general studies that calculate the own- or cross-price elasticity of organic products were not included as they do not focus on a specific intervention; only studies that evaluate the impact of specific marketing interventions on price elasticities were included. Due to the variability of production methods for sustainable foods and beverages, this review only included studies of certified organic foods and beverages, to ensure comparability. Previous systematic reviews have included studies of experimental marketing interventions, such as willingness to pay studies conducted in a hypothetical laboratory setting [4,7,11,12]. However, there is often substantial divergence between consumers’ reported behaviours in a laboratory setting and their actual behaviour in response to real-world stimuli [13–15]. As such, this review focused uniquely on real-world marketing in order to evaluate the impact of these types of interventions on consumer demand. Only study designs that included a control group, cohort, or pre-post intervention comparison were eligible for inclusion.
The search was restricted to articles published in English after 1 January 2010. Research has shown that introducing a date restriction of 10–15 years in systematic reviews does not substantially impact their validity [20]. Studies published earlier than 2010 are less relevant to this study due to their lack of emphasis on ‘new media,’ which has since become a crucial avenue of marketing communications in the food and beverage industry [10,21]. Moreover, policy-makers consider ‘recency’ to be one of the most important factors when evaluating evidence, necessitating a cut-off date of no earlier than 2010 [22]. The search was not restricted according to geography. The last search date was 18 January 2024. The full list of inclusion and exclusion criteria is outlined in Table 1.
2.3. Information sources and search strategy
Studies were identified by searching five databases, including: CAB Abstracts, EconLit, ABI/INFORM Global, Scopus, and Web of Science Core Collection. These databases include both peer-reviewed and grey literature. Search terms included marketing (and variations on this terminology, such as advertising), consumer demand (and variations, such as consumption, purchase, and behaviour), organic, and foods and beverages (and variations, such as fruits and vegetables). The full search strategy is included in S1 Appendix.
2.4. Study selection and data extraction
All identified records were imported into Covidence software (Veritas Health Innovation, Melbourne, Australia) for analysis and duplicates were removed. One author (AS) screened the study titles/abstracts against the inclusion criteria and identified articles for full text review. After included studies were identified, backward reference searches were conducted to identify additional relevant studies. Any uncertainties regarding study eligibility were discussed with a second author (LJ). One author (AS) extracted data from the included studies using a pre-piloted data extraction form. The data points extracted for each study are outlined in Table 2.
2.5. Risk of bias
Each study was assessed at the study level for risk of bias using the Evidence Project risk of bias tool [18]. The tool was designed for assessing the risk of bias of both randomised and non-randomised study designs, including observational and quasi-experimental studies. It has been validated for use in systematic reviews that include a range of study designs, making it a relevant tool for this review [18]. The tool specifies eight criteria for assessment: study design (cohort, control or comparison group, pre-post intervention data); participant representativeness (random assignment of participants to the intervention, random selection of participants for assessment, follow-up rate of 80% or more); and equivalence of comparison groups (comparison groups equivalent on socio-demographics, comparison groups equivalent at baseline on outcome measures). The Evidence Project tool measures a ‘Follow-up rate of 80% or more’; however, most of the studies included in our review did not include a follow-up design. We therefore scored studies based on whether they had a participation rate of 80% or more, which is a more suitable metric for this systematic review and is employed by other systematic reviews, as well [23]. We added two categories for controlling for gender and income, given the importance of these variables in determining customer demand for organic products [4,24–27]. The tool does not provide a quantitative score for each study, as the criteria cannot be directly compared or weighted equally. Instead, we summarise the results of the risk of bias assessment descriptively in section 3.3.
2.6. Data synthesis
The results were narratively synthesised based on their intervention type, according to McCarthy’s [9] ‘four P’ framework: product, price, place, and promotion. These four intervention types were then synthesised into 17 sub-categories, identified during the data analysis phase, as outlined in Table 3 below. Results were also narratively synthesised based on the outcome type (attitudes, intention to purchase or consume, actual purchases or consumption).
2.7. Methodological limitations
This systematic review employed a broad search strategy because of the diversity of the types of marketing interventions we were trying to capture. This ensured we captured a comprehensive range of studies and interventions, although it required us to screen a high volume of articles. The screening and full text review process was conducted by only one author; however, any uncertainties over whether a study should be included were resolved through conversation with a second author (LJ).
3. Results
3.1. Study selection
A total of 18,743 titles/abstracts were screened against the eligibility criteria and 191 full texts were reviewed. A total of 22 studies were deemed eligible for inclusion in the systematic review (see Fig 1).
3.2. Study characteristics
After excluding one of the 22 articles from narrative results due to ‘high risk’ of bias (see Section 3.3), 21 articles on 20 studies were included. Two articles were separate evaluations of the same study [28,29]. The 21 articles included observations of 17,502,635 individual consumers, 3,200 households, and 1,214 supermarket or hypermarket outlets (see summary study characteristics in Table 4).
Where reported, the sample sizes of studies ranged from 9 [28] to 17,494,986 individual consumers [30]. The proportion of female participants ranged from 32% [31] to 88% [32], while the mean age ranged from 24 years [33] to 46 years [34]. Socioeconomic status was typically reported (if at all) as proportions of different income brackets, making comparison across studies difficult; however, the samples tended to be relatively high income, in line with observations in the literature that organic consumers typically have higher income levels [4,27]. Education level was only captured in four studies, with tertiary education levels reported at 72% in a Netherlands-based study [32], 47% in Germany [35], and 37% in Denmark [34]; a fourth study of university students included 34% graduate students [33].
Sixteen studies were conducted in Europe, with Sweden (N = 5) and Germany (N = 4) most commonly studied; four studies were based in the United States and one in Australia. Eleven studies employed a non-randomised controlled trial design, seven studies employed a panel design, and three studies employed a pre-post design. Four studies [28,29,32,36] evaluated all (i.e. unspecified) product categories. Fruits and vegetables were the most commonly studied food categories (N = 10), followed by milk (N = 5), coffee (N = 4), meat (N = 4) and eggs (N = 4).
Eleven studies were conducted using secondary data sources, including household and consumer panel data, sales data, social media posts, Google search volume index data, and newspaper databases. Ten studies collected primary data in-person, including six studies in supermarkets or hypermarkets, one study in a fine-dining restaurant, one at a hotel lunch buffet, and one in a university canteen.
The study characteristics for each intervention are outlined in detail in Tables A-C in S2 Appendix.
3.3. Risk of bias
The majority of included studies were published in peer-reviewed journals, however, one was published in conference proceedings [29]. Most studies either did not report funding sources or reported that they did not receive funding. Of those that did report funding sources, four were funded by government research and development grants [28,36–38] and one study was funded by a Swedish foundation comprised of employers’ associations and national labour unions [38], presenting a low risk of bias. One study was funded by ‘St. Duurteelt,’ but no details about this funder were available online [32], and another study was funded jointly by a Dutch supermarket chain and an agricultural innovation program [39]; these studies have a slightly higher risk of bias in representing the interests of the funding bodies. However, the overall risk of bias from funding agencies was low.
Most studies implemented only one of the three study design characteristics of cohort, control or comparison group, and pre-post design. Only two studies [40,41] implemented random assignment of participants to the intervention and one study [32] implemented random selection of participants for assessment. Three studies [35,38,42] reported that comparison groups were equivalent at baseline for sociodemographic characteristics, while two studies [31,38] reported that comparison groups were equivalent at baseline on outcome characteristics. The participation rate was over 80% for four studies [28,29,34,42], while seventeen studies either did not report the participation rate, or it was deemed not applicable due to the study design.
One study [43] was excluded from the narrative results due to the poor study design. The study design included a comparison group for only a subset of outcomes and did not clearly state whether this comparison group pertained to organic products or to the product category as a whole. Katzeff et al. [28] was included despite having a poor study design, with a small sample size (N = 9 customers) and no comparison group or pre-post evaluation. The results of the Katzeff et al. [28] article are helpful in informing the Zapico et al. [29] evaluation of the same intervention and have been peer-reviewed. Moreover, the Katzeff et al. [28] study was a qualitative, interview-based study, which may account for its low score in the risk of bias evaluation, but which does not discount the validity of its findings.
The risk of bias assessment for each study is detailed in Table A in S3 Appendix.
3.4. Interventions and outcomes
No studies evaluated ‘product’ interventions. Four studies evaluated ‘price’ interventions, four covered ‘place’ interventions, and seventeen studied ‘promotion’ interventions (see Fig 2 and Table 5). These studies measured a variety of outcomes related to consumer demand, including consumer attitudes (N = 3), intention to purchase (N = 3); and actual purchases or consumption of organic foods and beverages (N = 20).
Count of studies presented by intervention type (price, place, promotion), sub-type, and outcome (attitudes, intention to purchase, actual purchases).
Tables A-C in S2 Appendix summarise each intervention and its impact on consumer demand, with outcomes and effect sizes presented separately for attitudes, intention to purchase, and actual purchases.
3.4.1. Price.
Price premiums. Two studies evaluated the impact of organic price premiums on consumer demand, both of which focused on actual purchases [32,39].
Van Doorn and Verhoef’s [32] study of 1,246 households over 40 weeks found a statistically significant negative impact of organic price premiums on the share of organic purchases (number of organic items purchased out of the total number of items purchased in a category, for 29 categories), suggesting an inverse relationship between price premiums and consumer demand [32]. A subgroup analysis of quality conscious and environmentally oriented customers, however, found a significant positive interaction effect with price premiums, suggesting that these customers were willing to pay a higher price for organic products.
Van Herpen et al.’s [39] study of organic market share at the store level across 60 supermarket outlets in the Netherlands over one sales quarter found that organic price premiums did not have a significant effect on organic market share of jarred vegetables, baby food, eggs, coffee, and milk.
Across these two studies, organic price premiums were thus found to have no effect, or a negative effect, on organic demand for the overall customer population, with a subset of the population being willing to pay a higher price.
Price promotions. Two studies evaluated the impact of price promotional intensity on actual purchases of organic foods and beverages [32,39]. Price promotional intensity indicates the frequency of price promotions within a product category [32]. When price promotional intensity within a product category is high, consumers tend to substitute products based on price, thus theoretically disadvantaging organic products, which are typically more expensive [32].
One study of 1,246 households found that consumers were significantly less likely to purchase organic items in categories with higher promotional intensity [32]. Another study of 60 supermarket outlets found that price promotions did not have a strong relationship with the sale of organic products [39]. When broken down into subgroups based on quality consciousness, health consciousness, and environmental orientation, the direction of impact was mixed [32]. Quality- and health-conscious consumers were less likely to purchase organic items in categories with high promotional intensity (a significant negative interaction effect), while environmentally oriented consumers were more likely to purchase organic items in categories with high promotional intensity (a significant positive interaction effect).
One study of consumer panel data in the United States examined the differential effect of price promotions (including the use of coupons or an in-store discount for the product) on 36 food categories [30]. They found that price promotion effects were stronger for organic versus non-organic products in ‘virtue’ (i.e., healthier) food categories, but weaker for organic products in ‘vice’ (i.e., less healthy) categories. The price promotion differential was not significant for other comparison groups, for example for fresh versus non-fresh categories.
Across these three studies, the effectiveness of price promotions thus differed depending on product category and customer type, so conclusions about the overall effectiveness of price promotions cannot be drawn.
Variation of organic prices. One study [37] evaluated a price-based intervention at a fine-dining restaurant in Oslo, Norway, where menu prices were altered such that the organic veal option was offered at a higher, identical, and lower rate to the non-organic menu options, which were held at a constant price. The 2-week intervention with a sample size of 462 customers found that both higher and lower prices resulted in statistically significant decreases in the choice of the organic option.
3.4.2. Place.
Nature sounds within store. One study evaluated a non-randomised controlled trial in a Swedish supermarket, where nature sounds were played in the fresh produce section over the speakers [38]. The study was conducted over 12 days, surveying 627 customers in-store about their intention to purchase organic carrots. The study found that nature sounds positively and significantly influence the intention to purchase organic carrots in men; however, the effect was not significant for women, resulting in mixed effects on organic demand overall.
Product arrangement. Two studies evaluated the impact of product arrangement on consumer demand for organic foods and beverages [35,39]. One study was a comparison of two German supermarket outlets, one where organic products were clustered together and one where organic products were dispersed throughout the store [35]. They surveyed 217 customers over a 3-day period and found that those exposed to the clustered arrangement had a more positive attitude towards the retailer’s organic range, as compared to those exposed to the dispersed arrangement [35]. The other study was a retrospective evaluation of retail data from 60 supermarket outlets in the Netherlands with varied product arrangements (clustered, brand-based, price-based). They found that arranging organic products in a cluster or by brand had a significant, positive impact on organic market share (number of organic items purchased out of the total number of items purchased in that category), while arranging products based on price did not significantly impact organic market share [39]. Across these two studies, clustering of organic products or arrangement by brand was found to have a positive effect on consumer demand for organic products, while dispersed or price-based arrangements did not have a positive effect.
Product availability. Two studies evaluated the impact of product availability on organic market share [32,39]. One study was an evaluation of consumer panel data for 1,246 households and retail sales data over two periods of 20 weeks, for 29 food and beverage categories [32]. They measured availability as the number of organic options available in a category compared to total number of options available in that category. The study found that organic product availability has a statistically significant positive effect on the share of organic purchases. Broken down by subgroups of quality consciousness and environmental orientation, the authors found that quality conscious and environmentally oriented consumers were willing to purchase organic items even when their availability was low (a significant negative interaction effect). Another study measured the number of shelf facings dedicated to organic products across nine product categories in a retrospective evaluation of 60 supermarkets across the Netherlands. They found that the relative amount of shelf space allocated to organic products did not significantly impact the organic market share [39]. Across these two studies, one found that organic product availability had positive effects on organic market share, while the other found no significant effect.
Product positioning. One study evaluated the impact of product positioning on organic market share [39]. Product positioning metrics included the vertical and horizontal shelf position of the product and the squared distance to the middle shelf. This retrospective evaluation of 60 supermarket outlets across the Netherlands was conducted over 13 weeks (i.e., one retail sales quarter) for nine product categories, although only five categories are named in the article: jarred vegetables, baby food, eggs, coffee, and milk. Results were not disaggregated by product type. The study found an inverted, U-shaped relationship between vertical shelf position and market share, with vertical shelf position and squared distance to middle shelf having a significant impact on organic market share. The best shelf position was reported as just above the middle of the shelf. Horizontal shelf position (i.e., whether the product was at the edge of the category) was not significant.
3.4.3. Promotion.
Educational film. One study evaluated the impact of exposure to an educational film, Food Inc., on consumers’ actual purchases of organic foods and beverages, across 786 stores in the United States [44]. Food Inc. was a 2008 documentary film that critiqued the corporate food industry in the US and which posited organic, locally grown food as a solution. This retrospective pre-post evaluation measured exposure to the film through Google search stock values for the film title. The study found that a 1 SD increase in the Google search stock value for the film had a significant positive effect on organic market shares, measured as a weighted mean across three product categories (coffee, yoghurt, and peanut butter). When broken down into product category sub-groups, a 1 SD increase in search stock value for the film Food Inc. had a significant positive effect on organic market shares for yoghurt and peanut butter–a 0.66% and 0.15% increase in market shares, respectively–but not for coffee.
Messaging near product display. One non-randomised control trial evaluated the impact of messaging near an organic carrot display on consumers’ intention to purchase organic carrots over 12 days in a Swedish supermarket [38]. The messages consisted of a sign over the carrot display, stating “Eat more organic carrots!” for the treatment group and “Eat more carrots!” for the control; an additional treatment for climate-friendly carrots was also included. The study found that organic messaging did not impact intention to buy organic carrots in women, regardless of their level of connectedness to nature. By contrast, organic messaging positively impacted intention to purchase in men when they had high levels of connectedness to nature and negatively impacted intention to purchase when they had low levels of connectedness to nature.
Five studies evaluated the impact of organic messaging near the product display on consumers’ actual purchases or consumption [41,42,45,46]. One study was a retrospective pre-post evaluation of an organic shelf labelling intervention at a hypermarket in Sweden over 521 days, measuring actual purchases through changes in the quantity of organic products sold per category [45]. The study found that shelf labelling significantly increased store-wide sales for organic olive oil (43%) and coffee (21%); the impact on flour sales was not significant. Another shelf-labelling study focused on changes in the likelihood of purchasing an organic product per category, with this likelihood derived from observations of consumers’ actual purchasing behaviour [41]. This study was a non-randomised control trial at a large German supermarket outlet, conducted over two weeks. The authors found differing results depending on the product category; the purchase of pasta and vegetables was significantly more likely with the stimulus, while there was no significant change in purchasing behaviour for eggs and fruits. Conversely, a third non-randomised controlled trial at a Swedish mid-sized supermarket found that signs with a happy face next to organic tomatoes and peppers (no sign next to non-organic alternatives) were associated with less purchases compared to control weeks, while signs with normative messaging about the organic product for lemons, carrots, lettuce, broccoli and spinach had no significant effect [46]. Another non-randomised controlled trial at a university canteen in Italy found that the odds of purchasing at least one vegetable plate were 17% lower with an organic label [33].
Finally, a fifth study focused on actual consumption (rather than purchases) of organic vegetables at an all-inclusive hotel lunch buffet in Apulia, Italy. This study was a non-randomised controlled trial implemented over 12 weeks, whereby organic messages were placed on top of the salad bar at the hotel buffet and compared to other interventions and a control group [42]. The authors found that organic messaging near the product display had a significant positive impact on aggregate daily consumption of organic vegetables. Overall, across the six studies, authors found mixed results, with messaging near organic products increasing demand for some product categories and subsets of consumers, but resulting in negative or no effects in other contexts.
Messaging on in-store screens. One study at a large and small supermarket outlet in Germany evaluated the impact of messaging on in-store screens on consumers’ actual purchases of organic milk [31]. The intervention involved exposing consumers to either a digital screen or an augmented reality screen, as well as comparing the use of high-construal (i.e., abstract) versus low-construal (i.e., concrete) messages on these screens.
According to construal level theory, humans perceive objects at different mental, or ‘construal,’ levels based on their psychological distance [31]. This distance can be spatial, temporal, social, or hypothetical [47]. Psychologically distant objects are perceived at a ‘high-construal’ or abstract level, while psychologically close objects are understood at a ‘low-construal’ or more concrete, detailed level. Previous studies [48,49], cited by Jäger and Weber [31], found that matching marketing messages to the construal level of the object positively impacted consumer behaviour. Jäger and Weber [31] identified that organic foods and beverages were high-construal objects and evaluated whether displaying high-construal messages (such as messaging about environmental responsibility) versus low-construal messages (such as detailed information about personal health benefits) positively impacted consumer purchases of organic milk. They found that there was a marginally significant difference in the volume of organic milk purchased based on the construal level of messaging, with low construal messages about the personal health benefits of organic milk proving more effective. There was no significant difference in the number of customers purchasing organic milk between the high construal versus low construal message framing.
The intervention also included comparing the effectiveness of digital screens versus augmented-reality screens. The digital signage consisted of a screen displaying an image of a model surrounded by four advertising messages, with four different iterations (local versus organic milk, and high-construal versus low-construal messaging), depending on the treatment. The augmented reality screen consisted of a ‘magic mirror,’ which was a screen displaying live video footage of the customer, surrounded by the same messages outlined above. The study found that when the results for the large and small store were grouped together, customers did not buy significantly more organic milk with experimental conditions compared to the baseline. When broken into subgroups, the large store saw a significant increase in the volume of organic milk purchased and in the number of customers purchasing organic milk when the technology treatment was present, compared to the control conditions without the advertisements. There was no significant difference between the treatment and control for the small store. The authors found no significant difference in the volume of organic milk purchased or the number of customers purchasing organic milk between the augmented reality ‘magic mirrors’ and the digital screens.
Messaging on print advertisements. One study evaluated the impact of messaging on print advertisements displayed in supermarkets on consumer demand for organic foods and beverages [40]. The study used construal level theory to construct a 2 x 2 between-subjects experimental design, where temporal distance (present-oriented versus future-oriented) and social distance (featuring humans as low distance versus animals as high distance) were the manipulated factors displayed on the stimulus, alongside EU organic and bio logos. They found that intention to purchase organic pork was positively impacted by the two stimuli with high social distance (i.e., animals, both in present and future). The study also used structural equation modelling to evaluate the impact of the stimuli on the link between intention and actual purchase behaviour for organic fruits, vegetables, eggs, milk and other dairy, spreads, and meat. They found that the two stimuli with high social distance (i.e., animals, both in present and future) had a positive significant impact on converting intention to actual organic purchases.
Newspaper coverage. Three retrospective evaluations examined the impact of both ‘positive’ and ‘negative’ newspaper coverage on consumers’ actual purchases of organic foods and beverages, specifically fruits, vegetables, and milk [34,50,51]. One study conducted a difference-in-differences analysis of newspaper coverage data and retail sales for 181 stores across the United States to examine the impact of newspaper articles that were either ‘positive’ (supportive) or ‘negative’ (critical) towards organic production generally, organic milk specifically, and the National Organic Program [50]. They found that aggregate organic milk sales increased by 5.1% relative to conventional milk sales during weeks with news coverage of any volume. They also found that the first relevant article increased sales of organic milk by 4.8% relative to conventional milk; each additional article also increased sales, but at a decreasing rate. When newspaper coverage was broken down by local versus national coverage, the study found that organic milk sales increased more in response to local news coverage (7%) as compared to national news coverage (4.5%). ‘Positive’ coverage had a statistically significant positive impact on organic milk sales, whereas ‘negative’ coverage did not have a statistically significant impact on organic milk sales.
Another study evaluated the impact of ‘positive’ newspaper articles (about the health benefits of consuming organic foods) versus ‘negative’ articles (about the detrimental impacts of pesticides in conventional food) in Denmark, with a sample size of 3,200 households [34]. They used a two-step model to first evaluate the probability of becoming a consumer of organic fruits and vegetables and then calculated the amount of organic fruits and vegetables purchased among organic consumers. They found that ‘negative’ messaging disseminated both directly (i.e., through newspapers) and indirectly (i.e., through word-of-mouth) had a significant positive impact on the probability of becoming an organic fruits and vegetables consumer. ‘Positive’ messaging had a significant positive impact on the probability of becoming an organic fruits and vegetables consumer when directly obtained, but a negative impact when indirectly obtained. Among organic consumers, both ‘positive’ and ‘negative’ messaging had a significant positive impact on the amount of vegetables (but not fruits) purchased, but only when directly disseminated. When indirectly disseminated, only ‘positive’ messaging had a significant positive impact.
A third study evaluated the impact of ‘positive’ versus ‘negative’ news coverage of organic dairy on consumers’ willingness-to-pay (WTP) for the organic attributes of milk, calculated based on actual purchasing data from 187 stores over 7 years [51]. They found that a 10% increase in ‘positive’ articles was associated with 0.36 cents increase in consumers’ WTP for organic milk, while a 10% increase in ‘negative’ articles was associated with 0.48 cents decrease in WTP for organic milk.
Across the three studies, ‘positive’ newspaper coverage was found to have positive impacts on demand for a subset of organic products, while ‘negative’ newspaper coverage had mixed results.
On-menu messaging. One study evaluated the impact of including organic messaging in menu descriptions on consumers’ choice of the organic menu option [37]. This non-randomised controlled trial was conducted at a fine-dining restaurant in Oslo, Norway, with 462 customers over a two-week period. The experiment involved changing the menu descriptions for the veal option, while holding all other menu descriptions constant. The veal description changed between a control description (“trio of veal from Grøndalen farm”), an organic description (“trio of organic veal from Grøndalen farm”), an animal welfare description (“trio of veal from Grøndalen farm from happy calves that have received much care and exercise”), and one that combined the organic and animal welfare descriptions. The study found that the organic nature of the veal was not a statistically significant driver of customers’ menu choice.
Online consumer purchasing dashboard. Two evaluations of the same intervention, one qualitative and one quantitative, studied the impact of an online consumer purchasing dashboard with messaging about the benefits of organic products on consumer demand, including the three domains of attitudes, intention to purchase, and actual purchases [28,29]. The intervention was a digital dashboard of real consumer purchasing information across all grocery items, which was updated daily based on actual in-store purchases. This dashboard provided data on the proportion of actual purchases that were organic and displayed messaging on the positive environmental, animal welfare, and human wellbeing impacts of choosing organic foods and beverages. 65 users were identified through self-selection by emailing employees and other affiliated contacts of the retailer where the study was being conducted; Zapico et al. [29] surveyed all 65 users, while Katzeff et al. [28] interviewed nine of these users.
Katzeff et al. [28] concluded that eight out of nine participants had a positive attitude towards organic foods. Zapico et al. [29] similarly found that the majority of participants agreed that food being organic was important to them when shopping, suggesting overall positive attitudes towards organic food.
Katzeff et al. [28] also found that eight out of the nine participants found the intervention motivated them to purchase more organic food. Zapico et al. [29] measured the impact of the intervention on consumers’ actual purchases by evaluating the percentage change in the monetary share of their purchases that were organic. They found that the treatment group saw a greater increase (23.3%) in the share of organic purchases over the period of the intervention, compared to the reference group (6.1%). Overall, the online purchasing dashboard with organic messaging positively impacted consumer attitudes, intention to purchase, and actual purchases; however, the evidence to support these findings is limited.
Public information campaign. One study evaluated the ‘Organic Spring’ public information campaign conducted by the French agency for the promotion and development of organic farming every year for two weeks [52]. They found that the campaign in 2007 and 2008 was associated with increased actual purchases of organic milk, but only for private label brands (not for national-level brands), and there was no lasting effect in the week after the campaign. The effectiveness of public information campaigns at increasing organic food and beverage demand is thus inconclusive due to the limited volume of evidence.
Social media posts. One study conducted a retrospective analysis of social media and retail sales data to evaluate the impact of social media posts on consumers’ actual purchases of organic foods and beverages [36]. This study evaluated 963 Facebook posts by a ‘green product retailer’ alongside aggregated weekly sales data for 28,709 members of the retailer’s loyalty program over 204 weeks. The authors found that social media posts statistically significantly increased weekly organic sales amongst loyalty program members by 21%. Broken down by the subject matter of the posts, price posts (6%), health posts (9%) and environmental posts (5%) all statistically significantly increased organic sales.
4. Discussion
Evidence from 21 analysed studies suggests that some marketing interventions are effective at increasing consumer demand for organic foods and beverages. However, there are very few open-access, academic studies that have explored organic marketing interventions in the real-world, particularly in comparison to the volume of evidence on real-world interventions to prompt other dietary changes, such as increased fruit and vegetable consumption [53–56]. Much more evidence is needed to understand the impacts of product, price, place and promotion interventions on actual demand for organic foods and beverages across a variety of product categories.
There is a particular need for real-world studies on product interventions, as we found no studies that met our criteria for real-world product-based interventions with a comparison group included in the study design. The lack of evidence is surprising given the widespread use of organic logos. Previous systematic reviews have estimated consumers’ willingness-to-pay for organic and other sustainability logos in hypothetical laboratory settings [11,12]; however, actual purchasing behaviour has been shown to differ from laboratory settings [13–15], necessitating further research into the effectiveness of product-based interventions in real-world contexts.
In line with existing literature on organic pricing interventions, including price premiums and promotions [11,57–59], the four included price studies [30,32,37,39] found different results depending on customer and product type. In general, the studies found that organic products behave as normal goods for typical consumers, whereby higher prices act as a deterrent and lower prices stimulate demand. However, a subset of consumers–who tended to be conscious of the health, quality, or environmental impacts of food–were found to treat organic products as a luxury good. This suggests that in order to increase organic purchases beyond the current niche groups of organic consumers, the price differential between organic and non-organic products needs to be addressed. However, given the sparsity of evidence (only four studies) and the variation in results by product and customer type, additional research is required to confirm these findings.
The evidence for place-based interventions was also limited (only four studies), necessitating additional real-world interventions to draw conclusions [32,35,38,39]. Preliminary results from two studies suggest that arranging organic products in a cluster, rather than dispersing them alongside conventional counterparts, had a positive effect on consumer demand [35,39]. This is in contrast to previous studies of plant-based meat replacement products, which have found that placing meat replacement products next to the meat display (rather than alongside other plant-based products) significantly increased product sales [60–62]. Other interventions, such as playing nature sounds in the store [38], altering vertical shelf position [39] and altering the relative availability of organic products [32,39], had mixed results or inconclusive evidence. Future studies of place-based interventions would benefit from distinguishing between ‘dedicated’ organic consumers and those who ‘switch’ between organic and conventional products based on convenience, as the plant-based food literature suggests that effectiveness of place-based interventions differs across these consumer types [60,63]. Additionally, most studies found variation in effectiveness across product categories, indicating a need for future research disaggregated by product type.
There was more evidence for promotional interventions (seventeen studies) than for any other type of marketing, although the results were heterogeneous depending on the type of intervention, product category, store, and customer. In line with the literature on marketing interventions for other types of sustainable foods, including healthy and environmentally friendly foods [64–66], shelf-labelling was found to positively impact consumers’ intention to purchase [38], as well as actual purchases [41,45] and consumption [42] of organic products in four out of six studies. However, intervention effectiveness differed by product category and store and customer type, reflecting the heterogeneity reported in the broader literature [64]. Newspaper coverage–particularly positive coverage of organic products–was found to positively impact consumer demand for some products [34,50,51]; however, the interventions focused only on milk, fruits and vegetables, necessitating further research across a broader array of product categories. Conclusions about the effectiveness of social media, educational films, online consumer purchasing dashboards, menu interventions, and public information campaigns cannot be drawn due to the limited volume of evidence. Two studies evaluated whether the construal-level of messaging impacted consumer demand for organics, differentiating between high-construal (abstract) and low-construal (concrete, detailed) messaging on in-store screens [31] and print advertisements [40]. These studies found mixed results and lacked robust study designs; additional research on whether abstract or concrete messaging is more effective at increasing consumer demand across a variety of product types would be useful to guide the design of future marketing interventions.
The majority of studies included in this review focused on actual purchases of foods and beverages, as opposed to actual consumption. Actual purchases of food may not always be an exact proxy for consumption of those foods in the household, due to factors such as food waste, for example. Ideally, studies of organic food demand would include actual consumption as a metric; however, this data is challenging to collect. Nonetheless, studies have shown that household purchases, when objectively documented, are a reasonably accurate and unbiased measurement of overall dietary quality, which corresponds to actual consumption [67–69]. Metrics for measuring actual purchases were highly varied, making it challenging to directly compare studies; there is thus a clear need for a more standardised set of metrics for evaluating the impact of marketing interventions on consumers’ actual purchases or consumption of organic foods and beverages.
None of the included studies evaluated consumer demand across all three dimensions: attitudes, intention to purchase, and actual purchases or consumption. This makes it challenging to disentangle the causal effects identified in the theory of planned behaviour, whereby consumers’ attitudes influence their intention to purchase, and their intention to purchase influences their actual purchasing behaviour [4,70,71]. Future research should evaluate each of these dimensions for a given intervention to unpack the causal chain of consumer food purchasing behaviour and thus enable better targeting of marketing interventions.
Many of the studies identified for inclusion in this systematic review lacked robust study designs. Future research on evaluating the impact of organic marketing interventions on consumer demand would benefit from combining comparison groups with pre-post analysis, in order to better isolate the specific impact of the intervention on demand.
Six out of the 15 analysed studies evaluated marketing interventions in supermarkets or hypermarkets, with only one study evaluating a restaurant setting, one evaluating a hotel buffet, and one a university canteen. Supermarkets are currently a major source of organic food purchases; in the UK, for example, 64.5% of organic sales were in supermarkets, followed by 18.3% through home delivery, 2.6% through the food service sector, and 14.6% through independent retailers [72]. Online sales (both through supermarkets and other retailers) are growing in importance. Future research should expand beyond supermarket evaluations to include studies of marketing interventions at independent retailers and food service companies, as well as evaluating online purchases. Moreover, while studies of individual stores are useful, research on consumer demand over broader geographies will prove insightful, particularly for the evaluation of larger-scale marketing interventions, such as mass media campaigns.
A major limitation of the sample of studies included in this review is that all of the studies were conducted in high-income countries, reflecting a broader inequity in representation of lower- and middle- income countries (LMICs) across academia. Organic demand is rising in fast-growing economies, with India, for example, ranking fourth globally in terms of global value growth [73]. Future research should therefore focus on these contexts, fore-fronting the work of researchers from these countries.
Relatedly, the study focused solely on certified organic foods and beverages, excluding foods that are produced sustainably but which are not officially certified. There are a plethora of non-certified products in the market because of the high barriers to entry for organic certification [74]. The exclusion of non-certified products may explain the lack of studies in LMICs, where certification is often cost-prohibitive for farmers [75].
This study was limited to the evaluation of publicly available research. Our search strategy and database selection included both peer-reviewed and grey literature; however, we found that no grey literature studies met the eligibility criteria. This may be due to limitations in study design, whereby comparison groups were not incorporated in the evaluation of real-world marketing interventions. It is also likely that many studies of real-world marketing interventions have been conducted by private companies, such as organic brands and supermarket chains; however, this data is not available to the public. In order to understand and promote organic food and beverage consumption in the future, greater collaboration and transparency of research on the marketing of organic products is critical.
5. Conclusion
This review is the first systematic synthesis of evidence about the effectiveness of real-world marketing interventions at increasing consumer demand for organic foods and beverages. There is no real-world evidence on the effectiveness of product-based interventions at increasing consumer demand, representing an important area for future research. Price premiums had no effect or negative effects on general consumer demand, in line with expectations for normal goods. However, for a subset of consumers, organic products took on characteristics of a luxury good and thus consumers were willing to pay higher prices. Price promotions had mixed effects depending on product and customer type. Some place-based interventions–such as arranging organic products in a cluster and ensuring ready availability of these products–had positive and statistically significant impacts on consumer demand. Some promotional interventions–such as including organic messaging near product displays and securing newspaper coverage–were generally effective at increasing consumer demand. However, the effectiveness of these promotional interventions differed across product categories, message framing, and the type of store and customer. Promotional interventions were most effective for olive oil, coffee, pasta, vegetables, and milk, and when concrete message framing was used. Across most of the studies, the effectiveness of price, place, and promotional interventions differed by product category, suggesting that organic foods and beverages are heterogeneous in demand, requiring category specific marketing interventions. Across the three domains of consumer demand, attitudes and intention to purchase were less studied and thus results were inconclusive. Impacts on actual purchases or consumption of organic foods and beverages was the most frequently used metric, yielding different results depending on the type of intervention. Future research needs to incorporate stronger study designs, including at least a comparison group and ideally randomisation in the selection and allocation of participants. There is a particular gap in the literature on the impact of marketing interventions on consumer demand in lower- and middle- income countries, necessitating further research in these contexts. Overall, our findings suggest that marketing interventions can be an effective driver of consumer demand for certain organic foods and beverages and could be incorporated alongside production-side interventions at local, regional, and national scales to boost the production and consumption of more sustainable agricultural products.
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