From Pixels to Palate: Communication around #vegan on Instagram and its relation with eating intentions.

Social media is an increasingly important yet understudied context for eating behaviors in general and veganism in particular. In four studies, we first explored and described the information environment the platform Instagram presents related to veganism. Second, we examined how engaging with this environment is associated with offline eating intentions via psychological mechanisms. We scraped datasets of Instagram posts tagged with #vegan (44,316 posts in total) and employed network analysis with their hashtags (Study 1), as well as clustering with images and sentiment analysis with texts (Study 2). Studies 3 (N = 117) and 4 (N = 251) used online surveys to investigate associations between different forms of engaging with social media content, psychological constructs, and offline eating intentions. Posts about veganism were frequently related to food, health and fitness, cosmetics, and photography. Images most often depicted food (34.7%), non-food products (30.4%), people (7.9%), and animals (2.0%). The sentiment of most posts was positive. Being exposed to Instagram content about veganism was more strongly and consistently associated with eating intentions than active forms of engagement. Attitude and self-identity emerged as the most relevant mechanisms for these effects. Food is the most prominent yet not sole topic among posts about veganism on Instagram, and hashtags used in this context partially relate to motives for following a vegan diet. Exposure to this information environment might influence offline eating decisions via psychological mechanisms. With growing usage and its potential influence, social media should receive increasing attention in (health) psychological research and practice.

The psychology of eating animals and veg*nism.

Vegetarian and vegan (Veg*n) diets are increasingly popular in Western societies and an increasingly common topic of psychological research. Animal-free diets hold considerable potential for helping curb the climate crisis and improving interspecies justice. This special issue presents recent contributions from research on the psychology of meat eating and veg*nism. To situate these articles in a broader context, we first establish the importance of studying veg*nism. We then review papers in this special issue, organized into themes of motivations and characteristics of veg*ns, attitudes towards veg*ns, attitudes toward meat and alternative proteins, intentions to eat meat or plant-based foods, consumption of meat or plant-based foods, and meat reduction interventions. We conclude with future directions for this blossoming field of study.

'Against the cult of veganism': Unpacking the social psychology and ideology of anti-vegans.

Despite the established health and ecological benefits of a plant-based diet, the decision to eschew meat and other animal-derived food products remains controversial. So polarising is this topic that anti-vegan communities - groups of individuals who stand vehemently against veganism - have sprung up across the internet. Much scholarship on veganism characterizes anti-vegans in passing, painting them as ill-informed, uneducated, or simply obstinate. However, little empirical work has investigated these communities and the individuals within them. Accordingly, we conducted a study using social media data from the popular platform, Reddit. Specifically, we collected all available submissions (∼3523) and comments (∼45,528) from r/AntiVegan subreddit users (N = 3819) over a five-year period. Using a battery of computerized text analytic tools, we examined the psychosocial characteristics of Reddit users who publicly identify as anti-vegan, how r/AntiVegan users discuss their beliefs, and how the individual user changes as a function of community membership. Results from our analyses suggest several individual differences that align r/AntiVegan users with the community, including dark entertainment, ex-veganism and science denial. Several topics were extensively discussed by r/AntiVegan members, including nuanced discourse on the ethicality and health implications of vegan diets, and the naturalness of animal death, which ran counter to our expectations and lay stereotypes of r/AntiVegan users. Finally, several longitudinal changes in language use were observed within the community, reflecting enhanced group commitment over time, including an increase in group-focused language and a decrease in cognitive processing. Implications for vegan-nonvegan relations are discussed.

Going veggie: Identifying and overcoming the social and psychological barriers to veganism.

We conceptualize the journey to ethical veganism in the stages of the transtheoretical model of change, from precontemplation through contemplation, preparation, action, and maintenance. At each stage, we explore the psychological barriers to progressing towards veganism, discuss how they manifest, and explore ways to overcome them. It is hoped that this paper can be used as a guide for animal advocates to identify the stage an individual is at, and understand and overcome the social and psychological barriers they may face to progressing. We argue that, while many people are ignorant of the cruel practices entailed in animal farming, many deliberately avoid thinking about the issue, are unable to appreciate the scale of the issue, and simply tend to favour the status quo. When engaging with the issue of farm animal suffering, meat-eaters are largely driven by cognitive dissonance, which manifests as motivated reasoning aimed at protecting one's image of oneself and one's society. This is facilitated by confirmation bias and complicit media which cater to the preferred views of their meat-eating audience. Even once convinced of veganism, habit and willpower present further barriers to acting on those beliefs. This is all in the context of a speciesist and carnistic culture where meat consumption is normal, farming is noble, and vegans are 'others'. We locate and elucidate each of these biases within the stages of the transtheoretical model and discuss the implications of this model for animal advocates and for further research.

Characteristics and clinical implications of the relationship between veganism and pathological eating behaviours.

OBJECTIVE: Veganism may serve as a socially acceptable means to restrict food intake and disguise pathological eating behaviours. Studies that include vegan participants typically group them with other meat avoiders (e.g., vegetarians), potentially masking risk factors unique to veganism. METHOD: We addressed this issue by recruiting two Amazon Mechanical Turk samples of 110 vegan and 118 omnivore participants, with comparable gender composition. We aimed to examine whether vegans showed higher disordered eating than omnivores, and if motives for pursuing a vegan diet impacted disordered eating. We assessed disordered eating using the Eating Attitudes Test, the Eating Disorder Examination-Questionnaire, and the Eating Pathology Symptom Inventory. RESULTS: Vegans displayed more pathological eating behaviours than omnivores, which was significantly predicted by cognitive restraint. However, body dissatisfaction levels were higher in omnivores than vegans. Diet motives did not influence vegans' disordered eating. CONCLUSION: We propose vegans have high levels of cognitive restraint, possibly due to their intention to avoid animal products. In turn, cognitive restraint subscales in eating disorder measures might be over-pathologising rates of eating disorders in vegans. Future research should monitor the progression of people's eating-related attitudes and behaviours before and after they transition to veganism to establish whether veganism increases the risk of disordered eating, or vice versa. LEVEL OF EVIDENCE: IV, cross-sectional study.

"If I became a vegan, my family and friends would hate me:" Anticipating vegan stigma as a barrier to plant-based diets.

A significant body of literature has developed which examines why meat consumption continues to be so important to Americans. Our paper contributes to this literature by examining how fear of stigmatization may be a barrier to avoiding meat consumption. This is an important subject because there is evidence that suggests that individuals who avoid meat, especially vegans, are stigmatized for disrupting social conventions related to food. In this paper, we present data from a series of focus groups in which vegan, vegetarian, and omnivorous college students discussed perceptions of vegans and veganism. Our analysis shows that non-vegans anticipate stigma associated with eating like vegans. We identify two strategies by which non-vegans attempt to avoid this stigma: social and behavioral distancing. These results suggest that vegan stigma is a barrier that inhibits dietary shifts toward a plant-based diet. Our results are important because they can be used to improve the efficacy of public health initiatives focused on encouraging plant-based diet adoption and meat consumption reduction.

A social identity needs perspective to Veg*nism: Associations between perceived discrimination and well-being among Veg*ns in Turkey.

We examined the associations between perceived discrimination, social identity need satisfaction, and well-being among a sample of vegetarians and vegans (veg*ns) in Turkey. Drawing on the Rejection Identification Model, Motivated Identity Construction Theory, and the Social Cure approach, we tested whether perceived discrimination was related to the satisfaction of esteem, meaning, belonging, efficacy, distinctiveness, and continuity needs derived from veg*n group membership and whether the satisfaction of these needs, in turn, was associated with psychological well-being and self-esteem. A total of 350 veg*ns living in Turkey participated in an online study and completed measures of perceived discrimination based on veg*n group membership, veg*n identity need satisfaction, psychological well-being, and global level self-esteem. As expected, perceived discrimination was prevalent among Turkish veg*ns (more so among vegans) and was strongly associated with the greater satisfaction of all identity needs. In turn, the satisfaction of efficacy and continuity needs was related to greater well-being, showing an indirect association between perceived discrimination and well-being. Findings also showed that the satisfaction of the esteem need predicted (less strongly) lower levels of psychological well-being and self-esteem, indicating only some aspects of need satisfaction through veg*n identities to have positive implications for well-being. Findings are discussed in terms of the relevant socio-cultural environment, social identity theories, and stigmatization in the context of veg*n group membership.

"More than a diet": A qualitative investigation of young vegan Women's relationship to food.

One's relationship to food is an important factor that can contribute to wellbeing but can also lead to eating disturbances. Research in this area has linked vegetarianism and veganism to disordered eating. However, through social media, many young women have recently started to share their vegan experiences with many highlighting the role that veganism may have on promoting a 'healthier' psychosocial relationship to food. The current study aims to qualitatively explore the role that veganism plays in young women's wellbeing and relationship to food. Participants were ten young vegan women aged 18 to 25. Semi-structured interviews were analysed using Interpretative Phenomenological Analysis (IPA). These women were found to passionately engage in a vegan lifestyle, as opposed to just a vegan diet, which appeared to have a number of positive effects such as a healthier lifestyle, a stronger sense of control and agency, more meaningful social relationships, and a sense of connection to a vegan sub-culture. Through veganism, many of the women transitioned from social disconnection and a focus on body image, to a stronger emotional (empathic), cognitive (knowledge of animal cruelty and healthy eating), and behavioural (diet and consumption choices, connections with others) investment in their social worlds. We suggest that the healing potential of veganism, is derived from this passionate investment of the self that redefines young women's ways of being in the world. The healing benefits of engaging in a vegan lifestyle may have clinical significance for working with young women who are socially disengaged or who are at risk of disordered eating.

What does the ORTO-15 measure? Assessing the construct validity of a common orthorexia nervosa questionnaire in a meat avoiding sample.

Orthorexia nervosa (ON) is a proposed diagnostic category that captures a pathological need to eat healthfully. The ORTO-15 is a self-report measure ostensibly designed to assess ON, but its suitability for capturing symptoms of pathology has been questioned. Vegans differ from omnivores in their focus on health and present with similar or lowered endorsement of eating behaviors symptoms, making them an ideal group to assess the construct validity of the ORTO-15. We tested the hypothesis that the ORTO-15 captures normative, rather than pathological, health focus. In total, 106 omnivores, 34 meat reducers, 50 lacto-ovo-vegetarians, and 191 vegans completed the ORTO-15 to quantify the presence and severity of ON and the Eating Disorder Examination Questionnaire (EDE-Q) as an established measure of eating pathology. More than 75% of respondents met criteria for a diagnosis of ON per established ORTO-15 cutoffs. Respondents above the 2.50 EDEQ cutoff (suggesting the likely presence of an eating disorder) did not differ in ORTO-15 scores from those scoring below the cutoff. There was a univariate main effect of meat avoidance type on the EDE-Q global scale (p < .01), with vegans endorsing fewer symptoms on the EDE-Q than semi-vegetarians (post-hoc p < .05). Vegans were more likely to meet the clinical ON cutoff of 40 on the ORTO-15 compared to omnivores (omnibus p < .01; post-hoc p = .01). Based on the ORTO-15, vegans' scores should be indicative of pathological eating behavior, but EDE-Q scores instead indicate the lowest levels in this group. The ORTO-15 is able to differentiate between types of meat avoiders, but given the difference in health focus between groups, the scale may be tapping into a construct other than pathological eating beliefs and behaviors.

Ethical concerns regarding animal use mediate the relationship between variety of pets owned in childhood and vegetarianism in adulthood.

Plant-based and vegetarian diets have been shown to have diverse health and environmental benefits and also serve to reduce farmed animal exploitation. It is therefore worthwhile to gain a better understanding of the factors that play a role in the decision to refrain from animal products. Past studies have shown that childhood pet ownership predicts the likelihood of adherence to a vegetarian diet in adulthood. Building on this research, we tested the hypothesis that the number of different types of pets owned in childhood is positively associated with degree of restriction of animal products in adulthood, and that this relationship is mediated by pro-animal attitudes. A self-selected convenience sample of 325 participants (77.2% female; mean age = 30.23 ± 12.5) reported on their vegetarian status and completed the Animal Advocacy Scale and Child Pet Ownership Questionnaire. The number of different pets owned in childhood was positively correlated with degree of vegetarianism in adulthood (p < 0.001), but was no longer a significant predictor when controlling for moral opposition to animal exploitation. A significant Sobel test (z = 4.36; p < 0.001) confirmed the presence of full mediation. Findings support the hypothesis that individuals who owned a greater variety of pets in childhood endorse more concerns regarding animal use. This, in turn, appears to predict the decision to refrain from animal products in adulthood. The possibility that an enhanced ability to generalize empathy from companion to laboratory, farm, and wildlife animals underlies this relationship should be examined in future research.

Conservatism predicts lapses from vegetarian/vegan diets to meat consumption (through lower social justice concerns and social support).

Lapses from vegetarian and vegan (i.e., veg*n) food choices to meat consumption are very common, suggesting that sustaining veg*nism is challenging. But little is known about why people return to eating animals after initially deciding to avoid meat consumption. Several potential explanatory factors include personal inconvenience, meat cravings, awkwardness in social settings, or health/nutrition concerns. Here we test the degree to which political ideology predicts lapsing to meat consumption. Past research demonstrates that political ideology predicts present levels of meat consumption, whereby those higher in right-wing ideologies eat more animals, even after controlling for their hedonistic liking of meat (e.g., Dhont & Hodson, 2014). To what extent might political ideology predict whether one has lapsed from veg*n foods back to meat consumption? In a largely representative US community sample (N = 1313) of current and former veg*ns, those higher (vs. lower) in conservatism exhibited significantly greater odds of being a former than current veg*n, even after controlling for age, education, and gender. This ideology-lapsing relation was mediated (i.e., explained) by those higher (vs. lower) in conservatism: (a) adopting a veg*n diet for reasons less centered in justice concerns (animal rights, environment, feeding the poor); and (b) feeling socially unsupported in their endeavor. In contrast, factors such as differential meat craving or lifestyle inconvenience played little mediational role. These findings demonstrate that ideology and justice concerns are particularly relevant to understanding resilience in maintaining veg*n food choices. Implications for understanding why people eat meat, and how to develop intervention strategies, are discussed.

Orthorexic and restrained eating behaviour in vegans, vegetarians, and individuals on a diet.

PURPOSE: Orthorexic eating behaviour, restrained eating, and veganism/vegetarianism are food selection strategies sharing several characteristics. Since there are no studies investigating their interrelationships, aim of the present study was to analyse orthorexic and restrained eating behaviour in (1) a sample of vegans and vegetarians and (2) a sample of individuals on a diet to lose weight. METHOD: Division of samples according to pre-defined criteria in (1) vegans (n = 114), vegetarians (n = 63), individuals with rare meat consumption (n = 83) and individuals with frequent meat consumption (n = 91) and in (2) participants on a diet with dietary change (n = 104), without dietary change (n = 37) and a control group of individuals not on a diet (n = 258). Orthorexic eating behaviour was assessed with the Düsseldorfer Orthorexie Skala and restrained eating was assessed with the Restraint Eating Scale. RESULTS: Vegans and vegetarians do not differ in orthorexic eating behaviour, but both groups score higher in orthorexic eating behaviour than individuals consuming red meat. There are no differences regarding restrained eating. Individuals on a diet with dietary change score higher in both orthorexic and restrained eating, than individuals without dietary change and individuals not on a diet. CONCLUSIONS: Individuals who restrict their eating behaviour, either predominantly due to ethical reasons or with the intention to lose weight, display more orthorexic eating behaviour than individuals not limiting their food consumption. Further research is needed to investigate whether veganism, vegetarianism, or frequent dieting behaviour serve as risk factors for orthorexia. LEVEL OF EVIDENCE: Level V, cross-sectional descriptive study.

Vegetarianism, depression, and the five factor model of personality.

This study investigated whether vegetarians and omnivores differ in their personality characteristics. We measured the five factor model of personality and depressive symptoms in vegetarians, who avoided meat and fish (n = 276); semi-vegetarians, who ate some meat and/or fish (n = 1191); and omnivores (n = 4955). Although vegetarians and semi-vegetarians were more open to new experiences, they were more neurotic and depressed than omnivores. Neither conscientiousness nor agreeableness varied as a function of dietary habits. These findings contribute to our understanding about differences between vegetarians' and omnivores' personalities, which might help us better understand individual differences in food preferences.

Motives of consumers following a vegan diet and their attitudes towards animal agriculture.

The number of consumers following a vegan diet has notably increased in many industrialised countries and it is likely that their influence on the food sector will continue to grow. The aim of the present study was to identify different segments of consumers according to their motivation for following a vegan diet. Another objective was to analyse the attitudes of these consumers towards animal agriculture. The main focus was to determine whether all consumers following a vegan diet oppose animal agriculture in general or if some of these consumers accept certain forms of animal agriculture. The 2014 study, conducted at seven vegan supermarkets in Germany, was based on face-to-face interviews with 329 consumers following a vegan diet. The open question on consumer motivations for adopting a vegan diet revealed three main motives: Animal-related motives (mentioned by 89.7% of the respondents), motives related to personal well-being and/or health (69.3%), and environment-related motives (46.8%). The two-step cluster analysis identified five consumer segments with different motivations for following a vegan diet. The vast majority of respondents (81.8%) mentioned more than one motive. We conclude that making a dichotomous segmentation into ethical versus self-oriented consumers, as previous authors have done, disregards the fact that many consumers following a vegan diet are driven by more than one motive. The consumer segments had significantly different attitudes towards animal agriculture. We identified consumers following a vegan diet (about one third of the sample) who might be open to forms of animal agriculture guaranteeing animal welfare standards going beyond current practices. The present study has interesting implications for the food sector and the agricultural sector.

Rationalizing meat consumption. The 4Ns.

Recent theorizing suggests that the 4Ns - that is, the belief that eating meat is natural, normal, necessary, and nice - are common rationalizations people use to defend their choice of eating meat. However, such theorizing has yet to be subjected to empirical testing. Six studies were conducted on the 4Ns. Studies 1a and 1b demonstrated that the 4N classification captures the vast majority (83%-91%) of justifications people naturally offer in defense of eating meat. In Study 2, individuals who endorsed the 4Ns tended also to objectify (dementalize) animals and included fewer animals in their circle of moral concern, and this was true independent of social dominance orientation. Subsequent studies (Studies 3-5) showed that individuals who endorsed the 4Ns tend not to be motivated by ethical concerns when making food choices, are less involved in animal-welfare advocacy, less driven to restrict animal products from their diet, less proud of their animal-product decisions, tend to endorse Speciesist attitudes, tend to consume meat and animal products more frequently, and are highly committed to eating meat. Furthermore, omnivores who strongly endorsed the 4Ns tended to experience less guilt about their animal-product decisions, highlighting the guilt-alleviating function of the 4Ns.

The Psychosocial Aspects of Vegetarian Diets: A Cross-Sectional Study of the Motivations, Risks, and Limitations in Daily Life.

INTRODUCTION: The popularity of vegetarian and vegan diets is linked to various motivations, such as health, ethics, ecology, and social and religious influence. India has the highest proportion of vegetarians and vegans. The practise of these diets is linked to moral and health reasons and environmental concerns. Vegetarianism may also be associated with eating disorders such as orthorexia (ON). AIM: The main aim of this study was to determine the psychosocial aspects of vegetarian diets. Understanding these aspects is crucial for identifying potential risks and developing effective interventions. This study investigated the reasons for following vegetarian diets, the duration of dietary adherence, the occurrence of feelings of restriction in selected situations, and the risk of orthorexia and other eating disorders. METHODS: A questionnaire survey was conducted among 186 individuals (82 vegetarians and 104 traditional dieters) between October 2023 and April 2024. The survey was administered via a Computer-Assisted Web Interview (CAWI) using Google Forms, distributed through social media, forums, and private messages. The inclusion criteria for the study group included consent, an age over 18, and a vegetarian diet, excluding those with eating disorders or diseases requiring strict diet therapy. The control group criteria were similar, excluding vegetarians and those requiring special diets. Four unreliable questionnaires were excluded from the analysis. The survey consisted of four sections: metric data, the ORTO-15 questionnaire, the EAT-26 questionnaire, and the TFEQ-13 questionnaire. RESULTS: The main motivations for following vegetarian diets were ethical and environmental (86.9%) and health (32.1%) reasons. Over half of the vegetarians had been following a plant-based diet for over five years. Vegetarians were more likely to feel restricted in restaurants and when grocery shopping. The ORTO-15 results indicate a higher risk of orthorexia among vegetarians (48.8% vs. 29.4% in the control group; p = 0.00673). The EAT-26 questionnaire showed a higher, but not statistically significant, risk of eating disorders among vegetarians (23.8% vs. 14.7%; p = 0.11391). The TFEQ-13 showed no significant differences between groups (Subscale 1: food restriction, p = 0.77279; Subscale 2: lack of control in overeating, p = 0.91935; Subscale 3: eating under the influence of emotions, p = 0.16612). CONCLUSIONS: This study concluded that ethical and environmental considerations and a belief in health benefits mainly drive vegetarians. An analysis of BMI revealed no significant differences between groups. The ORTO-15 results suggest a higher risk of orthorexia among vegetarians. The EAT-26 indicated a higher, but not statistically significant, risk of eating disorders among vegetarians and vegans. The TFEQ-13 showed no significant differences in restrictive eating, lack of control in overeating, and emotional eating. Vegetarians were likelier to encounter dietary difficulties in restaurants and shopping but less likely to feel socially excluded.

Veganism and body weight: An N of 1 self-experiment.

The causal effect that veganism has on body weight has not been scientifically examined. An N of 1 self-experiment was conducted in which blinded body weight and additional behavioural and psychological measures were assessed during two phases of vegan vs. non-vegan lifestyle adherence. In study phase 1, body weight change was -0.8 kg over 1 month of veganism (vs. +0.5 kg non-vegan month). In study phase 2, weight change was -1.2 kg over two veganism months (vs. +1.6 kg non-vegan months). Behavioural and psychological measures were similar during vegan vs. non-vegan periods. Veganism appeared to reduce body weight in this N of 1 self-experiment.

Healthy Food on Instagram Social Network: Vegan, Homemade and Clean Eating.

Social media platforms have become part of many people's lives. Users are spending more and more time on these platforms, creating an active and passive digital footprint through their interaction. This footprint has high research potential in many research areas because understanding people's communication on social media is essential in understanding their values, attitudes, experiences and behaviors. Researchers found that the use of social networking sites impacts adolescents' eating behavior. If we define adolescents as individuals between ages 10 and 24 (WHO's definition), 76% of USA young people at age 18-⁠24 use Instagram, so the Instagram social network analysis is important for understanding young people's expressions in the context of healthy food. This study aims to identify the main topic associated with healthy food on the Instagram social network via hashtag and community analysis based on 2,045,653 messages created by 427,936 individual users. The results show that users most associate Healthy food with healthy lifestyle, fitness, weight loss and diet. In terms of food, these are foods that are Vegan, Homemade, Clean and Plant-based. Given that young people change their behavior in relation to people's behavior on social networks, it is possible to use this data to predict their future association with healthy food characteristics.

Institutional resistance to veganism: Constructing vegan bodies as deviant in medical encounters in Estonia.

This article examines institutional resistance to veganism, with a focus on the medical system. Based on a qualitative analysis of vegans' accounts of medical encounters in Estonia, collected via an online questionnaire, I argue that the vegan body is socially constructed as a deviant entity by medical professionals. I suggest that the medical professionals' perceptions of vegans are based less on the actual conditions of their bodies but more on ideas about what are socially and politically acceptable identities and (bodily) practices. Deviance is produced through association with the uneasy category of 'vegan'. The experiences of vegans in the medical system illuminate the role of powerful social institutions in resisting transition towards more ethical and ecologically sustainable food practices and in endorsing human exploitation of other animals.

Vegetarianism and veganism compared with mental health and cognitive outcomes: a systematic review and meta-analysis.

CONTEXT: Vegetarian and vegan diets are increasing in popularity. Although they provide beneficial health effects, they may also lead to nutritional deficiencies. Cognitive impairment and mental health disorders have a high economic burden. OBJECTIVE: A meta-analysis was conducted to examine the relationship between vegan or vegetarian diets and cognitive and mental health. DATA SOURCES: PubMed, Scopus, ScienceDirect, and Proquest databases were examined from inception to July 2018. STUDY SELECTION: Original observational or interventional human studies of vegan/vegetarian diets were selected independently by 2 authors. DATA EXTRACTION: Raw means and standard deviations were used as continuous outcomes, while numbers of events were used as categorical outcomes. RESULTS: Of 1249 publications identified, 13 were included, with 17 809 individuals in total. No significant association was found between diet and the continuous depression score, stress, well-being, or cognitive impairment. Vegans/vegetarians were at increased risk for depression (odds ratio = 2.142; 95%CI, 1.105-4.148) and had lower anxiety scores (mean difference = -0.847; 95%CI, -1.677 to -0.018). Heterogeneity was large, and thus subgroup analyses showed numerous differences. CONCLUSIONS: Vegan or vegetarian diets were related to a higher risk of depression and lower anxiety scores, but no differences for other outcomes were found. Subgroup analyses of anxiety showed a higher risk of anxiety, mainly in participants under 26 years of age and in studies with a higher quality. More studies with better overall quality are needed to make clear positive or negative associations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42018097204.