Consumers switching to veg*n diets: A systematic review of the literature

Researcher Network member, Galareh Salehi, and colleagues present a recently published systematic review of how consumers shift to and maintain veg*an diets.

Abstract:

Omnivorous diets have several negative impacts on public health, environment sustainability and animal welfare. Switching to more responsible consumption choices such as vegan, vegetarian or plant-based (veg*an) are healthier, sustainable, and ethical dietary alternatives. There is a growing interest in studying veg*anism and veg*an diets. However, veg*anism continues being overlooked in research, especially within the domain of social-psychology and consumer behavior. Consequently, knowledge toward adhering to veg*an diets remain very limited. This paper aims to review and synthesise the related literature on how consumers shift to and maintain veg*an diets. A systematic literature review is conducted through the following four phases: search strategy, exclusion criteria, inclusion criteria, and data extraction. Total of 33 papers were reviewed. Results of synthesised studies showed the process of switching to veg*an diets started by awareness, continued by attitude development, fueled by various motivations, and supported by social and physical factors. These factors could be assessed by more representative and larger samples of consumers in the future.

Keywords: vegan diet; vegetarian diet; plant-based diet; consumer behavior; systematic literature review

1. Introduction

The omnivorous dietary practices (consuming both animal-derived and plant-based foods) is the social norm in most of the world (Armstrong Soule & Sekhon, 2019). There are many global on-going discussions on the several consequences of omnivorous diets. The main negative outcomes of these diets could be classified to (1) consumers’ physiological and psychological health; (2) environmental sustainability, and (3) animals’ welfare/rights (Neumane et al., 2020). Switching from omnivorous diets to plant-based, vegetarian or vegan diets (hereafter, veg*an diets) are closely linked with reducing or eliminating those negative consequences of animal-based food consumption (Weibel et al., 2019).

Veg*an diets have been understood in a continuum of least-strict to most-strict practices (e.g., Beardsworth and Keil 1991) aiming to decrease the amount and/or variety of animal-origin food products (Figure 1)[1]. The least-strict item, the omnivores, consume high volume of animal-origin food and low amounts of fruits and vegetables. Consumers’ attempts for reducing the meat intake locates them in two groups:  flexitarians, those who choose less or without meat meals if they were available, or reducetarians, those who attempt to reduce their meat consumption at least one day a week. The pescatarians consume fish, dairy foods, and eggs but not other kinds of meat. Plant-based dieters, food choices are “dominated by fresh and minimally processed plant-based foods” such as seeds, legumes, nuts, and products made from these foods such as seitan, tempeh, or tofu “and decreased consumption of meat, eggs and dairy products” (Wyker & Davison, 2010, p.170). Vegetarians abstain from all types of meat categories, yet still consume other animal-origin food products (e.g., eggs, and/or dairy products). Vegan diet, which is the most extreme practice in the continuum, excludes all animal-origin food products (Larsson et al., 2003).

It should be noted that a vegan diet is distinguished from veganism. According to Díaz (2017), vegan diet refers to a food practice, whereas veganism is a philosophy, a lifestyle, and a political movement that rejects, for moral reasons, the use of animals for human gain. Therefore, veganism eliminates as far as practicable and possible, all forms of exploitation of non-human animals for food, clothing, cosmetics and drugs, entertainment or any other purpose (The Vegan Society, 2016) and, by extension, suggests the consumption of products that are animal-friendly.

Figure1. Omnivore-vegan dietary continuum

Source: adapted from Beardsworth & Keil (1991)

There is an extensive body of non-medical literature studying veg*an consumption patterns (e.g., Zickfeld et al., 2018) or veg*an food choice (e.g., Allen & Baines, 2002). Despite consumption patterns and food choice decisions, the conscious commitment to follow a new diet is noticeably more consequential and an impressive decision (Wyker & Davison, 2010). However,this line of research is scant, and little is known about the transition to veg*an diets. (McDonald, 2000).. In addition, designing successful behavioral interventions need to be tailored for distinguished groups of consumers based on their dietary preferences and adoption process. Moreover, to date, there is no published systematic review on this subject. In light of above arguments, this systematic review focuses on consumers’ conversion process from omnivorous to veg*an diets.

2. Methodology

Following guidelines of Denyer and Tranfield (2009), the methodology of this systematic review is performed in four phases: (1) search strategy, (2) exclusion criteria, (3) inclusion/selection criteria, (4) data extraction .

(1) Search strategy. The potentially relevant papers were identified through an onscreen search of keywords through main electronic databases including WOS, Google scholar, Scopus, , Sciencedirect , Sagepub, Springer Link, Taylor & Francis, Wiley Online Library, Emerald insight, ProQuest, Brill, Ingenta connect, Oxford academic, MDPI, EBSCOHost, PsycINFO, and JSTOR. The searching for obtaining relevant articles is conducted in early June 2019, and again in March 2020. This systematic review is current as of 30th March 2020. Given the fact that above electronic sources encompass different domains and cover a varied category of research, the authors decided to occupy all of them.

(2) Exclusion criteria. Among different document types (articles; proceedings: 2,208; reviews: 1,869; meeting abstracts:724, and book chapters: 418) results refined to articles. Between the results of three main domains of WOS (core collection) categories chosen. Among JCR categories, nutrition dietetics (2,022), food science (1,043) behavioral science (141), ethics (111), sociology (91), economics (74), , philosophy (63), religion (49), social science interdisciplinary (35), business (35) and psychology social (34) were chose.

(3) Inclusion criteria. The inclusion criteria of identifying eligible studies was designed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) quality guidelines (Moher et al., 2009). Selecting eligible studies to be included for full manuscript review was evaluated based on (1) publication: if they were published in peer-reviewed (JCR or Scimago) journals; (2) language: and if they were written in the English language; (3) methodology: (3.1) research design nonempirical (conceptual) or empirical (quantitative, qualitative), (3.2) setting: restaurants or educational units, (3.3). 

3. Results and discussion

A total of 17,623 studies were identified through keyword search in electronic databases. The initial results were refined based on (1) document type and (2) research category. In the next step, the duplicated results were removed and 305 papers remained. The reference list of the 305 identified papers were screened and 41 papers added to the selected papers. The 346 selected papers were full text reviewed and evaluated based on the inclusion criteria. As a result, only 33 articles were eligible for data extraction. Selected studies’ research designs are as follows: non-empirical papers (n=1); mix-methods (n=3); quantitative methods (n=11), and qualitative methods (n=18). Among 32 empirical studies, 20 studies were conducted in the US, 3 in Australia, 3 in Canada, 2 in the UK, and 4 in European countries. All of 33 studies focused on one of the dietary behavioral changes in the omnivore-vegan continuum. For example, Weible et al. (2019) studied meat-reduction; Lea et al. (2006) investigated plant-based diet adherence; Boyle (2011) studied vegetarian diet; and McDonald (2000) and Mendes (2013) explored and conceptualized becoming vegan.

Regarding the aims and content of the papers selected in this systematic review, the following three themes can be highlighted: socio-demographic profile, motives, and process. 

Socio-demographic profile. Veg*an consumers have similarities in their socio-demographics and have differences in their dietary practices and motivations. Veg*an consumers are more likely to be female, high educated, middle or upper-middle social class, high IQ, and high physical and spiritual well-being (Díaz, 2012; Gale et al., 2007; Hirschler, 2011). 

Motives. Several motivations influence consumers to shift to veg*an diets. Usually, consumers switch to veg*anism with one motivation butand during their veg*an career their motivation may become multi-stranded.  Moral or ethical, health, sensory preferences, and  environment sustainability are the main motives of switching to veg*an diets (Beardsworth & Keil, 1991). World hunger, political concerns, social conditions of productions or religious beliefs were, in a lesser extend, other reasons of veg*an diets adherence (e.g., Merriman, 2010). Additionally, consumers usually start adopting veg*anism motivated by one motive but they become multistranted during the process (Boyle, 2011). 

Process. Three subtopics stand out: (1) Awareness and attitude development, (2) Social network and physical features and (3) Relapsing. 

Awareness and attitude development. Switching to veg*an diets usually start with memorable encounter experiences, i.e. an exposure to an event or educational materials or a direct experience (Chuck et al., 2016). The encounter experiences, interplaying logic (mainly health-motivated veg*ans) and/or emotions (mainly ethical-motivated veg*ans). Becoming conscious toward the issue usually follows by repression experience, i.e. confronting emotional and conflicting information (MacNair, 2001; McDonald, 2000). The conflicts of new information and emotions, depending on the subject’s physical and psychological capacity (Graca et al., 2019) may result in attitude change (see e.g. Rest, 1986), this is important because positive attitudes toward veg*an diets are the main determinant of consumers’ decision-making to switch to these diets (Klöckner, 2017) that are usually fueled by different motivations (Barr & Chapman, 2002).

Social network and physical features. The marginalized dietary group membership may put consumers at higher risk for rejection by their social networks (Chuck et al., 2016). Many veg*ans avoid telling people their dietary status to not be stereotyped (Romo & Donovan-Kicken, 2012). Therefore, veg*an relationships and communities are crucial especially in gradual process of veg*anism adherence (Beardsworth & Keil, 1991; Cherry, 2015). In this line, results of Haverstock & Forgays (2012) shows that those veg*ans who joined a vegetarian or vegan community group maintained their diet for a longer duration. However, many veg*ans have difficulties to find social support (MacNair, 2001), especially from family members (e.g. parents), this could explain why many of them would continue his/her veg*anism practice after being independent (Beardsworth & Keil, 1991; Worsley & Skrzpiec, 1998). This hostility from their friends and family does not influence men and women in the same manner: while significant others are favorable or neutral to men’s veg*anism adherence, they react negatively to the same dietary change in women (Merriman, 2010). In addition to social network influence, physical feature such as vegan food availability and affordability play a significant role on consumers’ veg*anism adherence (Menzies & Sheeshka, 2012).

Relapsing. Some of veg*ans choose lapsing or reversion from veg*an diets temporarily or permanently  (Beardsworth & Keil, 1991). Similarly to veg*anism adherence, abandoning veg*anism is usually a process for consumers as a response to inconvenience in difficult social and individual situations. However, it seems that those with ethical motives toward animal welfare usually maintain their veg*anism longer with low chances of relapse (Jabs et al., 1998). Former veg*ans mainly resumed their diet based on health-related reasons, personal and social inconvenience, meat cravings, and they showed political conservatism (Barr & Chapman, 2002). 

4. Conclusion

There is a growing interest in studying veg*anism and veg*an diets. However, veg*anism continues to be  overlooked in research, especially within the domain of social-psychology and consumer behaviour. Consequently, knowledge toward adhering to veg*an diets remains very limited. This paper aimed to review and synthesis the related literature on how consumers shift to and maintain veg*an diets. 

The systematic review of 33 studies generated 3 main conclusions: First, veg*an consumers have some similarities in their socio-demographic characteristics (e.g., female, high-educated). Second, they have differences in their dietary practices (see omnivore-vegan continuum) and motivations (e.g., animal-related, environment-related). Finally, regardless of their profile characteristics, the process of switching to veg*an diets usually starts by awareness, continued by attitude development and fueled by motivations, and maintained by social and physical factors. 

Considering the limited geographical scope of the studies and the lack of large and random sampling in both quantitative and qualitative studies, above conclusions are not necessarily generalizable. Therefore, it is suggested to conduct empirical future research with quota sampling, hypothetical and theory-based designs. Moreover, considering yet the novelty of veg*an dietary practice, more consistent and conclusive research is needed. 

Gelareh Salehi

(Comillas Pontifical University, Spain, gsalehi[at]comillas[dot]edu)

Estela Díaz Carmona

(Comillas Pontifical University, Spain, emdiaz[at]icade.comillas[dot]edu)

Raquel Redondo

(Comillas Pontifical University, Spain, rredondo[at]icade.comillas[dot]edu)

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