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The Impact of a Vegan Diet on Many Aspects of Health: The Overlooked Side of Veganism

1 Internal Medicine / Nephrology, Geisinger Health System, Wilkes-Barre, USA

2 Medicine, Geisinger Commonwealth School of Medicine, Scranton, USA

3 Medicine, Geisinger Medical Center, Danville, USA

4 Internal Medicine, Geisinger Health System, Wilkes-Barre, USA

Vegetarianism in any of its various forms, particularly veganism, has been increasing in popularity over the past few years, especially among the young population in the United States. While several studies have shown that a vegan diet (VD) decreases the risk of cardiometabolic diseases, such as cardiovascular disease, type 2 diabetes mellitus, obesity, and non-alcoholic fatty liver disease, veganism has been associated with adverse health outcomes, namely, nervous, skeletal, and immune system impairments, hematological disorders, as well as mental health problems due to the potential for micro and macronutrient deficits. The goal of this review article is to discuss the current literature on the impact and long-term consequences of veganism on vulnerable populations, including children, adolescents, pregnant and breastfeeding women, and fetal outcomes in strict vegan mothers. It also focuses on the many deficiencies of the vegan diet, especially vitamin B12, and the related increased risk of malignancies.

Introduction and background

Vegetarianism in various forms has gained widespread popularity in recent years. These types include vegans, who adhere to the most stringent dietary restrictions, omitting all animal-source foods and their by-products from the diet. Others include lactovegetarians (no meat, fish, or eggs but do consume dairy goods), ovo-vegetarians (no meat, fish, or dairy products but do consume eggs), lacto-ovo-vegetarians (no meat but do consume eggs and dairy products), and pescatarians (no meat except fish and shellfish) [ 1 , 2 ]. There has been growing interest in dietary habits given the worsening obesity epidemic and obesity-related health concerns [ 3 , 4 ]. Obesity is an established risk factor for diabetes mellitus, which, in turn, is an independent risk factor for coronary artery disease [ 5 ]. While studies have shown that a vegan diet (VD) may be associated with improved health outcomes [ 6 , 7 ], the negative health repercussions of these food preferences, on the other hand, are rarely highlighted, and veganism may be associated with negative health effects due to nutritional deficiencies.

Additionally, vegans have a greater prevalence of mental health problems, which may lead to a poorer quality of life. An optimal diet should be balanced, consisting of lean meat, nuts, fresh fruits and vegetables, and olive oil (Figure ​ (Figure1) 1 ) [ 8 , 9 ]. A wholesome diet is essential in maintaining a healthy gut flora, which in turn is pivotal in avoiding inflammatory disorders [ 10 - 13 ]. The primary aim of this review will be to draw attention to the current literature associated with veganism, including the side effects of practicing a VD and long-term consequences for a variety of populations, including adults, adolescents, pregnant and lactating women, and the fetal outcomes of vegan mothers.‬‬‬‬‬‬

A recent systematic study examined the intake and adequacy of the VD in terms of macro and micronutrient intake in the adult European population. The study found that vegans consumed the least total protein compared to other diet groups, confirming concerns that VD may include insufficient protein, particularly in instances where legume, seed, and nut consumption is limited [ 14 ]. Vegans consume fewer essential amino acids than non-vegans [ 15 ]. Plant proteins are less digestible (50-70%) than animal proteins, and food processing methods like heating may further reduce digestibility. According to the WHO, animal proteins are considered complete proteins and have higher biological value, protein efficiency ratio, net protein utilization, and, ultimately, have a higher Protein Digestibility Corrected Amino Acid Score (PDCAAS) compared to plant proteins [ 16 , 17 ]. By and large, soy proteins constitute a significant protein source for most vegans [ 18 ].

Vitamin B12

Low vitamin B12 intake is a significant problem in vegan diets due to the exclusion of vitamin B12-rich foods such as meat, poultry, and eggs. A lack of vitamin B12 has been linked to neurologic and hematologic problems [ 19 ]. Low vitamin B12 intake has serious clinical consequences, although deficient symptoms appear gradually over time. High folate levels may also partly and temporarily obscure some of the typical vitamin B12 hematological manifestations. To prevent vitamin B12 deficiency, vegans must get their levels checked regularly and meet their daily requirements via supplements or fortified foods.

A growing body of research indicates that inadequate B12 consumption may contribute to carcinogenesis. Vitamin B12 deficiency increases uracil misincorporation, impairing DNA synthesis and genomic instability. Global hypomethylation of DNA is a characteristic of early carcinogenesis. Thus, if not adequately replaced, VD may inadvertently lead to cancers [ 20 ]. Wu et al found that blood B12 levels were substantially lower in menopausal and postmenopausal breast cancer patients, and patients with the lowest B12 levels had an elevated risk of breast cancer [ 21 ]. Reduced B12 levels have also been linked to an increased risk of cervical and gastrointestinal tract malignancies [ 22 - 24 ]. As a result, B12 supplementation is imperative for vegans due to the extensive and irreversible detrimental effects of the deficiencies.

Other minerals and micronutrients

Vegans have greater iron needs than other diet patterns [ 25 ], mainly because non-heme iron from plant-based foods is less bioavailable, as absorption is hindered by whole grains, legumes, and nuts due to their phytic acid content [ 26 ]. Vegans also have a zinc deficit. While meat, dairy, and eggs contain zinc, some zinc-rich plant foods (e.g., nuts, seeds, and whole grains) have poor bioavailability owing to the presence of phytate, which inhibits absorption in the gut [ 16 ]. Inadequate zinc consumption may be associated with mental health problems (e.g., depression), dermatitis, diarrhea, and alopecia, all of which are more prevalent among vegans [ 27 , 28 ]. Selenium insufficiency has also been seen among vegetarians.

Vitamin D, calcium, bone mineral density, and risk of fractures

Numerous studies have shown that vegans consume insufficient calcium and vitamin D, not only owing to the absence of dairy products but also due to calcium bioavailability problems in plant-based diets [ 28 ]. Vitamin D insufficiency exacerbates calcium shortage further owing to impaired intestinal absorption. After adjusting for socioeconomic variables, lifestyle covariates, and body mass index (BMI), a recent study reported that as compared to meat-eaters, there was an increased risk of hip fractures observed in vegetarians (HR 1.25; CI 1.04-1.50), vegans (2.31; 1.66-3.22), and fish eaters (1.26; 1.02-1.54) [ 29 ]. Vegans also had a greater incidence of overall fracture (1.43; 1.20-1.70), leg fractures (2.05; 1.23-3.41), and fractures in other major sites (1.59; 1.02-2.50). The higher risk of fractures may be related to vegans' significantly lower calcium intake, reduced dietary protein intake, and lower BMI [ 30 - 32 ].

Mental health

The most recent systematic review [ 33 ], which included eighteen studies, compared meat abstainers versus meat eaters in terms of mental health. The research included 160,257 individuals (85,843 females and 73,232 men) from various geographic areas, including 149,559 meat eaters and 8584 meat abstainers (aged 11 to 96 years). Eleven of the 18 studies found that meat-free diets were linked with worse psychological health, four were inconclusive, and three found that meat-free diets resulted in improved results. The most thorough research found that meat-avoiders (i.e., "full vegetarians") had a 7.4%, 24.1 %, and 35.2% 1-month, 12-month, and lifetime prevalence of unipolar depressive disorders, respectively. In contrast, meat consumers had a much lower prevalence: 6.3%, 11.9%, and 19.1%. Similarly, the 1-month, 12-month, and lifetime prevalence of anxiety disorders for meat abstainers were much higher at 20.4%, 31.5%, 31.5%, and 10.7%, 17.0%, and 18.4% in the meat eaters respectively. The study highlights the high incidence of mental health problems among vegans, emphasizing the vital need of increasing awareness of these illnesses to facilitate early intervention. Women notably appeared to be adversely impacted by mental disorders such as stress [ 34 - 36 ].

Orthorexia nervosa (ON) is defined as a fixation on health-conscious eating behavior [ 37 ]. It involves obsessive (compulsive) food decisions, self-imposed anxiety, self-punishment, and increasingly extreme limitations. As a result of diet-related concerns, individuals develop dietary restrictions, lack of food pleasure, inflexible and rigid eating behaviors, and ritual activities surrounding food preparations. Vegetarian, and vegan, women are more prone than males to have disordered eating attitudes and practices [ 38 ].

Although some studies indicate a reduction in mortality associated with vegetarianism and VD, the larger body of evidence indicates that the health benefits associated with vegetarianism may be due to other “lifestyle” factors associated with socioeconomic statuses, such as adequate physical activity, low alcohol, and drug consumption, or avoidance of tobacco products. Recently, Johnston et al. argued that the evidence supporting public health recommendations to reduce or eliminate meat intake was based on questionable studies and "inappropriate analysis" [ 39 ]. This argument and the growing body of contrasting and conflicting findings create a conundrum for doctors and policymakers alike.

Effects on children and adolescents

Adolescents are also known to show a strong preference for VD. A balanced diet is critical for children and adolescents to meet their bodies' rising demands during the growth spurt, rendering the implications of VD in this vulnerable age more intriguing. A recent study examined the anthropometry, dietary intakes, and nutritional status of 149 vegetarians, 115 vegans, and 137 omnivore children and adolescents using a cross-sectional design (6-18 years old, mean age: 12.7 ± 3.9 years) [ 40 ]. Vegetarians and vegans consumed more carbohydrates than omnivores (p = 0.0002). Vegetarians (p = 0.02) had the lowest protein consumption, however, vitamin B2, D3, HDL-C, and triglyceride blood concentrations did not differ between diet groups. The authors concluded that there are no specific nutrient concerns among vegetarian, vegan children and adolescents compared to omnivores. The study's cross-sectional design and lack of representativity should be considered when interpreting the findings.

In contrast to the above study, subsequent cross-sectional studies showed that vegetarian and/or vegan children had a lower bone mineral density (BMD) [ 41 , 42 ]. Desmond et al. observed that vegetarians and vegans were shorter than omnivores (-0.32 and -0.57 height z scores, respectively), but the difference was non-significant in vegetarians [ 42 ]. The research showed that after controlling for body size, vegan children had substantially lower vitamin D levels and BMD than omnivores. It is suggested to maximize childhood BMD to promote peak BMD and therefore reduce the risk of osteoporosis and fracture in adulthood. The authors concluded that vegans had lower BMDs even when body and bone size were taken into consideration. It does not seem to be ideal to start puberty, a period when bone-specific nutrition requirements are greater, with an already established BMD deficiency. If such deficiencies continue throughout adolescence as a result of a diet, they may raise the likelihood of poor bone outcomes later in life. Prospective longitudinal studies are required to better understand the consequences of VD on children and adolescents.

Effects on pregnancy, fetal outcomes, and lactation

Optimal fetal growth requires balanced maternal nutrition during pregnancy. Mothers on rigorous VD are at risk of vitamin insufficiency, which can lead to poor fetal outcomes. A recent study included 273 women, including 112 omnivores, 37 fish eaters, 64 lacto-ovo-vegetarians, and 60 vegans, respectively [ 43 ]. In comparison to an omnivorous diet, the vegan diet was substantially linked with an elevated risk of small-for-gestational-age infants (RR = 5.9, 95 percent CI, 1.2-21.8). All the groups had a similar incidence of preterm births. Birthweight in vegans was lower compared to lacto-ovo-vegetarians (3015 ± 420 g vs. 3285 ± 482 g, P = 0.004) and to omnivores (3328 ± 495 g, P < 0.001) but not to fish-eaters. Vegans also had a lower mean gestational weight gain compared only to omnivores (11.6 ± 4.2 kg vs. 14.3 ± 4.6 kg, P = 0.001). A review of 13 low and middle-income nations found low docosahexaenoic acid levels in breast milk in mothers on plant-based diets but greater in the fish-eating population [ 44 ].

Maternal B12 status influences their offspring’s B12 levels and is an independent risk factor for neural tube defects (NTD) [ 45 ]. Studies have shown an association between low B12, low birth weight, and pre-term delivery [ 46 ]. A Chinese study associated increased maternal pickled vegetable consumption with NTD due to excessive nitrate, nitrite, and N-nitroso compound content [ 47 ]. They found that eating pickled vegetables more frequently (>6 meals/week) increased the risk of NTD. The investigators also found that maternal consumption of meat, eggs, or milk (>1 meal/week) reduced the risk of NTD. Vegan mothers may have poor prenatal nutritional status, resulting in low maternal fat reserves for breastfeeding. The postpartum nutritional profile of vegetarian mothers declines without sufficient energy intake, thus maternal nutritional reserves are lost to promote infant normal development. 

Providers should evaluate a woman's nutrition and energy consumption frequently. Women on restrictive diets may need to take supplements or eat fortified foods to meet the required needs throughout pregnancy and breastfeeding. Plant-based diets during pregnancy and breastfeeding need a heightened awareness of the importance of consuming all necessary nutrients and vitamin supplements, as recommended by international guidelines [ 48 ].

Conclusions

While veganism has been shown to decrease the risk of cardiovascular and metabolic syndrome, it also carries the potential for micro- and macronutrient deficits. It should be noted that vegans often have better socioeconomic levels, live a healthier lifestyle with more physical exercise, and tend to smoke less compared to non-vegetarians, making it difficult to isolate the effects of veganism in observational research. Existing research is often skewed by selection bias, which is when the study sample is chosen based on prior eating patterns and such studies are often recruited in environments with a high level of health awareness. Our review focuses on the impact of veganism on vulnerable populations, including children, adolescents, pregnant and breastfeeding women, and fetal outcomes in strict vegan mothers. Vegans should be closely monitored and treated for nutritional deficiencies, in order to mitigate any long-term negative health outcomes. Given the growing interest in diets without animal protein intake in the general population, it is crucial, now more than ever, to have a clear understanding of both the risks and benefits of such diets among clinicians, policymakers, and the public.

The content published in Cureus is the result of clinical experience and/or research by independent individuals or organizations. Cureus is not responsible for the scientific accuracy or reliability of data or conclusions published herein. All content published within Cureus is intended only for educational, research and reference purposes. Additionally, articles published within Cureus should not be deemed a suitable substitute for the advice of a qualified health care professional. Do not disregard or avoid professional medical advice due to content published within Cureus.

The authors have declared that no competing interests exist.

Forty-five years of research on vegetarianism and veganism: A systematic and comprehensive literature review of quantitative studies

Affiliations.

• 1 Faculty of Economics and Business Administration, Universidad Pontificia Comillas. ICADE, Spain.
• 2 Business Management Department, Spain.
• 3 Quantitative and Statistical Analysis Department, Spain.
• PMID: 37223710
• PMCID: PMC10200863
• DOI: 10.1016/j.heliyon.2023.e16091

Meat production and consumption are sources of animal cruelty, responsible for several environmental problems and human health diseases, and contribute to social inequality. Vegetarianism and veganism (VEG) are two alternatives that align with calls for a transition to more ethical, sustainable, and healthier lifestyles. Following the PRISMA guidelines, we conducted a systematic literature review of 307 quantitative studies on VEG (from 1978 to 2023), collected from the Web of Science in the categories of psychology, behavioral science, social science, and consumer behavior. For a holistic view of the literature and to capture its multiple angles, we articulated our objectives by responding to the variables of "WHEN," "WHERE," "WHO," "WHAT," "WHY," "WHICH," and "HOW" (6W1H) regarding the VEG research. Our review highlighted that quantitative research on VEG has experienced exponential growth with an unbalanced geographical focus, accompanied by an increasing richness but also great complexity in the understating of the VEG phenomenon. The systematic literature review found different approaches from which the authors studied VEG while identifying methodological limitations. Additionally, our research provided a systematic view of factors studied on VEG and the variables associated with VEG-related behavior change. Accordingly, this study contributes to the literature in the field of VEG by mapping the most recent trends and gaps in research, clarifying existing findings, and suggesting directions for future research.

Keywords: 6W1H; Systematic literature review; Veganism; Vegetarianism.

© 2023 Published by Elsevier Ltd.

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• Published: 22 April 2020

Prevalence and psychopathology of vegetarians and vegans – Results from a representative survey in Germany

• Georgios Paslakis 1 , 2 ,
• Candice Richardson 1 ,
• Mariel Nöhre 3 ,
• Elmar Brähler 4 , 6 ,
• Christina Holzapfel 5 ,
• Anja Hilbert 6 &
• Martina de Zwaan 3  

Scientific Reports volume  10 , Article number:  6840 ( 2020 ) Cite this article

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An Author Correction to this article was published on 10 November 2020

This article has been updated

The aim of the study was to investigate the prevalence of, and attitudes toward, vegetarianism and veganism. We also assessed the association between vegetarianism/veganism and eating disorder, depressive, and somatic symptoms. A cross-sectional questionnaire survey in adults in Germany that was representative in terms of age, gender, and educational level was carried out. Data from 2449 adults (53.5% females) were included. Mean age was 49.6 (SD 17.1) years. A total of 5.4% of participants reported following a vegetarian or vegan diet. While the majority of participants agreed that vegetarian diets are healthy and harmless (56.1%), only 34.8% believed this to be true of vegan diets. The majority of participants also believed that a vegetarian (58.7%) or vegan (74.7%) diet can lead to nutritional deficiency. Female gender, younger age, higher education, lower body mass index (BMI), and higher depressive and eating disorder symptoms were found to be associated with vegetarianism/veganism. We did not find increased physical complaints in the group of vegetarians/vegans. Our results point toward a moderate prevalence of vegetarianism/veganism among the general population. Our findings suggest that health care professionals should keep eating disorder pathology, affective status in mind when dealing with individuals who choose a vegetarian/vegan dietary pattern.

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Introduction.

To date research about vegetarianism and veganism is still young even though plant-based nutrition seems to have gained increasing popularity and represents a growing social movement 1 . Vegetarianism is a generic term that encompasses a variety of dietary patterns that each involves, to some extent, the avoidance of meat 2 . While omnivores consume all types of animal products 3 , true vegetarians are defined as those who do not eat any meat, poultry, or fish 4 . Vegetarians may be further sub-classified based on the inclusion of eggs (ovo-vegetarians), diary (lacto-vegetarians), fish (pesco-vegetarians), poultry (pollo-vegetarians), or a combination of these foods in their diet 2 , 5 , 6 . Finally, vegans are those who refrain from eating any animal products, including meat, fish, dairy, eggs, and other animal-derived foods 3 . Individuals may adopt a vegetarian diet for a variety of reasons which may be ethical, moral, religious, environmental, health-related, or concerns about animal welfare 7 . The majority of recent studies suggest that ethical concerns are the most common motivation for adopting a vegetarian diet, followed by health considerations 3 , 5 , 8 . While health vegetarians avoid meat in order to derive the perceived health benefits of a vegetarian diet or to lose weight, ethical vegetarians avoid meat for animal welfare reasons 9 . The aim of the present study was to investigate the prevalence of, and attitudes toward, vegetarianism and veganism in a representative sample of the general adult population in Germany.

The prevalence of vegetarianism varies around the world with recent polls indicating that approximately 5% of Americans 10 , 8% of Canadians 11 , and 4.3% of Germans 6 follow a vegetarian diet. However, the highest proportion of vegetarians are found in India, where they comprise 30% of the population 12 , 13 . Veganism is less common with the prevalence reported to be about 2% in the United States 10 and less than 1% in Germany 14 . In several studies, education and income were found to be inversely associated with meat consumption 14 , 15 , 16 . Subsequent research conducted within Central European countries also indicates that vegetarians tend to be more educated and affluent than omnivores 14 , 17 . Allès et al . 18 confirmed that vegetarians tend to be more educated than omnivores, but also found out that vegans tend to have lower educational attainment. Additionally, women are far more likely to be vegetarian than men 8 ; even among non-vegetarians, women have been found to eat considerably less meat than men 1 , 14 , 19 , 20 .

Although strict and unbalanced dietary restrictions can pose a risk of micronutrient deficiencies 2 , it is the position of the Academy of Nutrition and Dietetics that appropriately planned vegetarian diets are nutritionally adequate and may be beneficial for health 21 . A comprehensive meta-analysis of 80 studies provides evidence for the link between a vegetarian diet and a lowered risk of cardiovascular disease, type 2 diabetes, obesity, and certain types of cancer 22 . Vegetarianism has also been associated with reduced risk of hypertension, diverticular disease, degenerative arthritis, and metabolic syndrome in other studies 4 , 23 . Also, the use of vegetarian and vegan diets is often associated with other health behaviors including non-smoking and regular physical activity 1 . Additionally, studies conducted in Western countries have consistently shown that vegetarians have a lower BMI compared to their non-vegetarian counterparts, with vegans having the lowest BMI 24 , 25 , 26 .

There is mixed evidence as to whether vegetarianism is associated with more positive or negative mental health 27 . Although vegetarians have reported more positive mood in some studies 28 , 29 , they have described more psychological symptoms associated with anxiety and depression in others 30 , 31 . Similarly, while some studies 32 , 33 , 34 have found a higher risk of depression among vegetarians, others 5 , 28 show no significant difference between vegetarians and omnivores. Furthermore, adolescent vegetarians were more likely to be depressed 35 and have contemplated suicide 36 when compared to adolescent omnivores. Adherence to a vegetarian diet has been hypothesized to be a factor in the development and maintenance of disordered eating 5 as the restrictive nature of the diet may be used as a socially acceptable way to refrain from eating specific foods 3 . The majority of studies 36 , 37 , 38 , 39 suggest that vegetarians exhibit greater levels of disordered eating than omnivores; however, two recent studies suggest that this may not always be the case 40 , 41 . Indeed, in one study by Timko et al . 5 , semi-vegetarians, defined as those who exclude red meat from their diet, were found to have the highest level of eating pathology, while true vegetarians and vegans appeared healthiest in regards to eating and body weight. Thus, it is important to understand attitudes toward plant-based diets and the potential association with eating disorder, depressive, and somatic symptoms, as these findings, in conjunction with those from additional longitudinal studies, can lead to the development of more specific guidelines for healthcare professionals to monitor patients that follow these types of diets.

While the primary aim of this study was to investigate the prevalence of, and attitudes toward, vegetarianism and veganism, we also assessed the association between vegetarianism/veganism and eating disorder symptoms, depressive symptoms, and the presence of somatic symptoms. We expected that consistent with previous studies, vegetarians/vegans would display a higher burden of eating disorder and general psychopathology.

Recruitment

A random sample of German residents aged 14 years and older (age range 14 to 91 years) were recruited as part of a cross-sectional survey on physical and mental well-being. For the purposes of the present investigation we only assessed adults (≥18 years of age). A demographic consulting company (USUMA GmbH, Berlin, Germany) assisted with sampling and data collection. The procedure was designed to yield a nation-wide sample representative in terms of age, gender, and educational level over the fieldwork period from May to July 2018. Sociodemographic data were collected in-person by trained interviewers and participants also completed a battery of self-report questionnaires.

Data acquisition

In Germany, no directory is generally available that contains the addresses of all private households or individuals, which could be used by market research agencies as a sampling frame. The data collected by the local authorities are only available for surveys considered to be of major public interest. A group of agencies called the “Arbeitsgemeinschaft ADM-Stichproben” closes this gap by providing a sampling frame to member agencies, the so-called “ADM-Sampling-System for Face-to-Face Surveys”. This frame allows representative face-to-face samples to be drawn for all households in Germany and for all people living in those households. In addition, the main statistical data are provided on a detailed level for this population. The ADM-Sampling-System is described in detail elsewhere 42 , 43 .

The participation rate was 46.9% (2531 of 5393 persons), taking into account all refusals to participate, as well as interviews that failed to take place due to respondents’ illness or being otherwise unavailable during the fieldwork. All participants provided their written informed consent in accordance with the Helsinki declaration. The study was approved by the Ethics Committee of the Medical School of the University of Leipzig.

The following sociodemographic data were assessed: gender (male and female), age (distinguished according to groups: 18–24, 25–34, 35–44, 45–54, 55–65, >65 years), educational level (<12 and ≥12 years), monthly income (0 to <1000, 1000–2500, and ≥2500 euros per month), population size (<5000, 5000–50000, and ≥50000 residents). The BMI was calculated based on participants’ self-reported height and weight.

Dietary assessment

To assess self-reported dietary patterns, participants were asked the following question “Have you been consciously eating a vegetarian diet for at least 2 weeks?” This question has been repeated for vegan diet. It was explained to participants that vegetarian means omitting meat, but eating plants and milk products, and vegan means omitting all foods of animal origin.

Subsequently, participants were presented with a series of 11 statements about vegetarian diets. The same statements were asked for a vegan diet. Participants responded to each statement using a 4-point Likert scale ranging from “totally agree” to “totally disagree”. All statements were short and simple:

A vegetarian diet is completely healthy and harmless.

A vegetarian diet can lead to a nutritional deficiency.

People who follow a vegetarian diet are seldom overweight.

Individuals who follow a vegetarian diet are more productive.

A vegetarian diet is able to prevent disease.

A vegetarian diet is good for the environment.

A vegetarian diet is less cruel to animals.

People who follow a vegetarian diet are made fun of.

A vegetarian diet is not tasty.

A vegetarian diet is expensive.

People who eat a vegetarian diet do so out of ethical motivation.

Additionally, omnivores were asked if a vegetarian or vegan diet would be a viable diet for them to pursue. All questions and statements were constructed and finally chosen from a larger pool by experienced nutritionists, physicians and psychologists.

Psychological assessment

Participants also completed the Patient Health Questionnaire-4 (PHQ-4) 44 , the Eating Disorder Examination-Questionnaire 8 (EDE-Q8) 45 , and a brief form of the Giessen Subjective Complaints List (GBB-8) 46 . The PHQ-4 allows for the brief measurement of depression and anxiety based on participants’ responses to 4 items on a Likert scale ranging from “not at all” to “nearly every day”. Total scores range from 0 to 12, and correspond to no (0–2), mild (3–5), moderate (6–8), or severe (9–12) psychological distress 44 . The EDE-Q8 is an 8-item self-report questionnaire used to assess eating disorder psychopathology. Scores range from 0 to 6, with higher scores indicating greater psychopathology 45 . Similarly, the GBB-8 is a brief, self-report questionnaire used to assess somatic symptom strain. Total scores range from 0 to 32, while scores on the four subscales (exhaustion, gastrointestinal complaints, musculoskeletal complaints, and cardiovascular complaints) range from 0 to 8 with higher scores indicating greater symptom strain 46 .

Statistical analyses

For analysis of the dietary statements, the answers “totally agree” and “agree” were grouped together, as were “disagree” and “totally disagree”. T-Tests or Chi-square tests were performed appropriately when comparing vegetarians/vegans with omnivores. In order to examine the predictive value of the independent variables, a binary logistic regression was performed with vegetarianism and veganism as dependent variable. The level of significance was set at p ≤ 0.05. Bonferroni correction for multiple testing was performed according to the number of independent variables in each hypothesis testing. Unweighted data were used. Statistical analyses were performed using SPSS (IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.).

Participants

A total of 2531 individuals participated in the survey. Of those, 82 were excluded for being younger than 18 years. Thus, data from a total of 2449 adults were analyzed. This cohort consisted of 46.5% (1138/2449) males and 53.5% (1311/2449) females. Mean age was 49.6 (SD 17.1) years, and 40.9% (1001/2449) of participants were aged older than 55 years. Additionally, the mean BMI was 25.9 (SD 2.1) kg/m 2 . More details on socio-demographics of the cohort are shown in Table  1 .

Prevalence of self-defined vegetarianism and veganism

When participants were asked whether they have followed a conscious vegetarian diet for at least two weeks, 5.2% (126/2444) indicated yes. The non-vegetarian participants were further asked whether a vegetarian diet would be a viable diet form to pursue. Of the 2316 respondents to this question, 11.2% (259/2316) indicated yes. In a similar manner, 1.3% (31/2446) of participants reported following a strict vegan diet. The non-vegan participants were further asked whether a vegan diet would be a potential diet form to adopt, to which 5.9% (142/2414) indicated yes.

There was considerable overlap in the endorsement of vegetarian and vegan dietary patterns. Of the 133 (5.4%) participants who reported following a vegetarian and/or vegan diet, 18% (24/133) answered “yes” to both questions, 76.7% (102/133) reported following a vegetarian but not a vegan diet, and 5.3% (7/133) indicated they followed a vegan but not vegetarian diet. Given this overlap, for the present analysis, those who endorsed a vegetarian and/or vegan diet were grouped together. Thus, the prevalence of current self-defined vegetarians/vegans was 5.4% in the present sample.

Attitudes toward vegetarian and vegan diets

When participants were asked about their attitudes toward a vegetarian diet, the majority of both vegetarians/vegans and omnivores agreed that a vegetarian diet is completely healthy and harmless, good for the environment, and less cruel to animals. The majority of both groups also believed that those who eat a vegetarian diet do so out of ethical motivation, and are seldom overweight. Conversely, the majority of both groups disagreed with the notions that vegetarians are made fun of and that a vegetarian diet is not tasty. While the majority of vegetarians/vegans agreed that vegetarians are more productive and that the diet can prevent disease, only a minority of omnivores agreed with these statements. Similarly, while the majority of omnivores agreed that a vegetarian diet is expensive and can lead to nutritional deficiencies, the majority of vegetarians/vegans disagreed with these statements. Full details are displayed in Table  2 .

Similarly, when asked about their attitudes toward a vegan diet, the majority of vegetarians/vegans and omnivores, again, agreed that those who eat a vegan diet do so out of ethical motivation, are seldom overweight, and that a vegan diet is good for the environment and less cruel toward animals. However, in opposition to their attitudes toward vegetarian diets, the majority of both groups believed that a vegan diet can lead to nutritional deficiency, and that those who follow a vegan diet are made fun of. While the majority of vegetarians/vegans agreed that a vegan diet is completely healthy and harmless, can prevent disease, and that those who follow a vegan diet are more productive, the majority of omnivores disagreed with these statements. Similarly, while the majority of omnivores agreed that a vegan diet is expensive and not tasty, the majority of vegetarians/vegans disagreed with these notions. Full details are displayed in Table  3 .

Comparison between self-defined vegetarians/vegans and omnivores

Comparing vegetarians/vegans to omnivores, no differences in income distribution or population size of the community or city of origin were found. Among vegetarians/vegans, a significantly higher proportion were female (73.7% vs. 26.3%; X 2 (1) = 23.174, p < 0.001). Additionally, vegetarians/vegans were significantly younger than omnivores (M = 40.9, SD = 15.5 vs. M = 50.0, SD = 17.0; t(2442) = −6.033, p < 0.001). Finally, 51.5% of vegetarians/vegans attained 12 or more years of education compared to 21.8% of omnivores (X 2 (1) = 61.531, p < 0.001). Vegetarians/vegans also had a significantly lower BMI compared to omnivores (M = 24.0, SD = 4.7 vs. M = 26.0, SD = 5.0; t(2423) = −4.555, p < 0.001). Similarly, vegetarians/vegans had significantly higher eating disorder psychopathology in the EDE-Q8 (M = 1.3, SD = 1.4 vs. M = 1.0, SD = 1.3; t(2440) = 2.619, p = 0.009), as well as slightly, but not significantly, higher depression scores in the PHQ-4 (M = 2.0, SD = 2.3 vs. M = 1.5, SD = 2.1; t(140) = 2.327, p = 0.21) scores compared to omnivores. More details are shown in Table  4 . In terms of somatic complaints, vegetarians/vegans and omnivores did not significantly differ in their experiences of exhaustion, gastrointestinal complaints, musculoskeletal complaints, cardiovascular complaints, or overall symptom strain (Table  5 ).

A binary logistic regression analysis was conducted to predict vegetarianism/veganism based on gender, age, education, population size, income, BMI, EDE-Q8 score, and PHQ-4 score. A significant regression model was found, χ 2 (8) = 835.0, p < 0.001: gender (female), (younger) age, (higher) education, (lower) BMI, (higher) PHQ-4 score, and (higher) EDE-Q8 score were significant statistical predictors of vegetarianism/veganism (Table  6 ).

The prevalence rate of self-defined vegetarians/vegans among the general German population found in the present investigation (n = 133, 5.4%) is comparable to that reported in an earlier German representative sample, in which the prevalence was found to be between 3% and 6% 14 . The current prevalence rate is also similar to those reported in US investigations 10 . A significant minority of omnivores reported that they would consider a vegetarian (11.2%) or vegan (5.9%) diet for themselves in the future showing that some people have an interest in adopting this kind of nutrition (“prospective vegetarianism”) 20 . Omnivores were more open to becoming vegetarian than to becoming vegan. However, meat consumption is still part of the traditional and social norm in Western societies 47 .

Regarding general attitudes toward vegetarian/vegan forms of diet in the general population, we noticed that both diet forms were considered expensive. Vegetarian and vegan diets are often perceived to be expensive 48 , and have therefore been associated with lower openness to try a vegetarian diet 49 . However, when compared to meat eaters, “true” vegetarians have been shown to report lower food expenditures 50 . While a vegetarian diet was considered to be healthy by most respondents, the majority did not think the same about vegan diets. This is in line with the German Nutrition Society which clearly states that a vegan diet cannot fulfill the daily recommendation for vitamin B12 intake and that supplementation is needed in most of the persons sticking on a vegan diet. Moreover, veganism is not recommended for pregnant and lactating women 51 . Additionally, almost two-third of the respondents said that vegans are made fun of and also a slight majority of respondents agreed that vegetarians are made fun of. Most respondents stated that vegetarian/vegan diet is less often associated with overweight. Vegan diet is not considered tasty. People have more negative beliefs about veganism than vegetarianism which is in line with literature. Literature also shows that vegetarians themselves report unfavorable social experiences 52 and biases with omnivores belittling their character 20 .

We found that female gender, younger age, lower BMI, higher depression scores, and higher eating disorder-related psychopathology were significantly associated with vegetarian/vegan diets. In terms of gender differences, this is entirely in accordance with the existing literature 1 , 8 , 14 . There is an extensive literature on the association between meat and masculinity 19 showing that men view meat as a more essential part of a proper diet. Thus it is not surprising that we found a higher proportion of females to be vegetarians/vegans. Similarly, we found that vegetarians/vegans were significantly younger than omnivores, as previously documented in multiple studies conducted among adults in Germany 14 , the UK, Canada, and the U.S 18 , 24 , 53 , 54 , 55 . Our findings are also in congruence with previous research showing an association between higher education and reduced meat consumption 14 , 15 , 16 , as over half of the vegetarians/vegans in our study attained 12 or more years of education compared to 22% of omnivores. Conversely, while previous research has documented greater affluence among vegetarians 14 , 17 , we found no difference in income distribution between vegetarians/vegans and omnivores in our sample. We also found vegetarians/vegans to have a lower BMI compared to their omnivorous counterparts; which is consistent with existing literature 10 , 24 , 25 , 26 .

Limited data is available on the associations between vegetarian diet and mental health 34 . While some studies have shown no significant differences in depressive symptoms between vegetarians and omnivores 5 , 28 , our results more closely align with those that have documented higher risk for 32 , 33 , 34 and more psychological symptoms associated with depression 30 , 31 among vegetarians/vegans. The prevalence of participants who screened positive for potential cases of depression and anxiety (PHQ-4 > 6) was 5.3% in omnivores and 8.5% in vegetarians/vegans. However, we cannot make any assumptions about causality. Do more depressed individuals select to follow a vegetarian/vegan diet or does following a vegetarian/vegan diet increase the risk for developing depression? It cannot be excluded that nutritional status may affect brain processes and may influence onset and maintenance of mental disorders 34 .

Our results allude to an association between choosing to subsist upon a diet excluding meat and displaying symptoms of disordered eating. The difference in EDE-Q8 scores remained even after adjusting for gender and age which are known to influence eating disorder symptoms. This result is in accordance to the majority of previous similar studies 36 , 37 , 38 , 39 , even though the overall scores in the present sample were close to scores found in the general German population 45 . In terms of the potential link between vegetarianism and the development of eating disorders, evidence from three retrospective chart reviews 56 , 57 , 58 show that approximately half of all patients diagnosed with anorexia nervosa report adhering to a vegetarian diet. Others have emphasized that this might represent a more orthorexic behavior with a fixation on health-conscious eating 59 . Furthermore, two-thirds of individuals with history of an eating disorder reported that their vegetarianism was related to the eating disorder as it allowed them to restrict caloric intake and increase feelings of control; however, the majority of these individuals also indicated that they adopted a vegetarian diet after the onset of their eating disorder 60 . Thus, vegetarianism may be a symptom of the disorder or a maintaining factor, rather than linked to its causal development 3 . As far as the clinical implications of our findings are concerned, our findings imply that health care professionals should keep the association between eating disorder psychopathology and vegetarian/vegan forms of diet in mind when dealing with individuals who choose this form of diet; especially in younger women. Similarly, affective status should be considered in the same group in question.

We did not find differences with regard to physical complaints between the groups of vegetarians/vegans and omnivores. Thus, although self-reported symptoms cannot be accounted for factual differences in health status between the two groups under investigation, we conclude that vegetarians did not differ in complaints of (somatoform) symptoms compared to the general omnivore population. In one German study vegetarians reported a better current health status than omnivores 14 . This finding is in contrast to another previous German investigation showing an increased prevalence for somatoform disorders in vegetarians 34 . Michalak et al . 34 found evidence for elevated prevalence rates in vegetarians not only for somatoform syndromes but also for depressive disorders, anxiety disorders as well as for eating disorders. This is the only study that did not rely on self-report but used clinical diagnoses of mental disorders as assessed with standardized diagnostic interviews and that controlled for socio-demographic characteristics. For depressive, anxiety and somatoform disorders the adoption of a vegetarian diet followed the onset of mental disorders and the authors hypothesized that a mental disorder increases the likelihood of choosing a vegetarian diet probably with the goal to positively influence the course of the disease.

There are some limitations to consider. The response rate was relatively low (46.9%), which is, however, common in general population research. The current use of vegetarian and vegan diets was self-reported, and it is known from previous studies that self-identified vegetarians do not necessarily completely abstain from meat 6 , 19 . Furthermore, we define “vegetarian/vegan” as a person who sticks to that diet for at least two weeks, which means, that this definition is rather lenient. Therefore, also short-term vegetarians/vegans might be within the survey. We did not assess the motivation for following a vegetarian or vegan diet. A further limitation lies in the lack of assessment of objective measures (e.g., BMI) and the reliance on self-reports. Additionally, considering that this was a cross-sectional study, and that the vegetarian/vegan group was mostly young females, it may be that young females are more prone to having an eating disorder regardless of the diet they follow. Thus, vegetarianism/veganism may be a symptom or maintaining factor of the disorder rather than linked to its causal development. Due to the cross-sectional design in this study, no conclusions can be made regarding the causality of the association between diet and the examined individual differences. In contrast, the strengths of our study are the inclusion of a large representative sample of the German population and the use of standardized questionnaires to assess depressive, eating disorder, and somatic symptoms.

Taken together, the prevalence of current and self-defined vegetarianism and veganism in the present research was 5.4% which is comparable to other German and international studies. People’s attitudes toward vegetarians and vegans still point toward some biases. Finally, the present survey showed that there are not only differences between self-defined vegetarians and omnivores in socio-demographics, but also in levels of eating-related symptoms and potential cases of depression and anxiety.

Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Change history

10 november 2020.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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G.P. and M.d.Z. designed the study. G.P. and C.R. conducted the statistical analyses. M.N., E.B., C.H., and A.H. participated in instrument selection and development of the questions on veganism and vegetarianism. The first draft was written by C.R. All authors reviewed the manuscript and accepted the final version.

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Paslakis, G., Richardson, C., Nöhre, M. et al. Prevalence and psychopathology of vegetarians and vegans – Results from a representative survey in Germany. Sci Rep 10 , 6840 (2020). https://doi.org/10.1038/s41598-020-63910-y

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Your diet is one of the first places to start if you’re looking to manage your health and weight. Focusing on whole foods from plant sources can reduce body weight, blood pressure and risk of heart disease, cancer and diabetes — and it can make your environmental impact more sustainable.

But how do we embrace plants in our diets if we’re so accustomed to including meat and dairy as primary nutrition sources?

We spoke with Dr. Reshma Shah, a physician, plant-based eating advocate, co-author of “Nourish: The Definitive Plant-Based Nutrition Guide for Families” and Stanford Healthy Living instructor, about simple ways to incorporate more plants into your diet and the benefits this can provide for both you and the planet.  

Focus on whole, minimally processed foods.

People use many different terms to describe a plant-based diet, including vegetarian, lacto-ovo vegetarian, pescatarian, and flexitarian to name a few. The most restrictive is veganism, which  excludes all animal products, including meat, eggs and dairy. 

While there are health benefits to adopting a vegan diet, highly processed foods with little to no nutritional value, like Oreos or French fries, could still be a legitimate part of a vegan diet.

In contrast, a whole-foods, plant-based (WFPB) diet: 

• Emphasizes whole, minimally processed foods
• Limits or avoids animal products
• Focuses on plant nutrients from vegetables, fruits, whole grains, legumes, seeds and nuts 
• Limits refined foods like added sugar, white flour and processed oils 

Recommendations from organizations including the U.S. Dietary Guidelines for Americans, World Health Organization, American Diabetes Association and American Cancer Society tout the benefits of plant-based whole foods and caution against high amounts of red and processed meats, saturated fats, highly refined foods and added sugar. 

The vast majority of what nutritional experts are saying reflects the mantra made famous by Michael Pollen in his book “The Omnivore’s Dilemma” — eat food, mostly plants, not too much . 

Eating a plant-based diet helps the environment.

According to a report by the U.S. Food and Agriculture Organization, “The meat industry has a marked impact on a general global scale on water, soils, extinction of plants and animals, and consumption of natural resources, and it has a strong impact on global warming.” 

The meat and dairy industries alone use one third of the Earth’s fresh water , with a single quarter-pound hamburger patty requiring 460 gallons of water — the equivalent of almost 30 showers — to produce.

Reducing your meat and dairy consumption, even by a little, can have big impacts. If everyone in the U.S. ate no meat or cheese just one day a week, it would have the same environmental impact as taking 7.6 million cars off the road.

Plant-based diets prevent animal cruelty. 

Ninety-four percent of Americans agree that animals raised for food deserve to be free from abuse and cruelty , yet 99% of those animals are raised in factory farms, many suffering unspeakable conditions . 

If you would like to lessen your meat and dairy consumption due to animal welfare concerns but aren’t ready to eliminate all animal products from your diet, then you can start by taking small steps, like going meatless one day a week or switching to soy, almond or oat milk. Shah admits that initially she was not ready to give up animal products entirely. 

“I think it is a process and recommend that people go at the pace that feels comfortable for them.” 

Plant-based diets include all nutrients — even protein.

According to the American Dietetic Association, “appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, and for athletes.”

Shah says that there are a few key nutrients that strict vegans and vegetarians should keep in mind, including B12, iron, calcium, iodine, omega-3 fatty acids and vitamin D, but all of these can be obtained through plant-based foods, including fortified plant-based milks, fresh fruits and vegetables or supplemental vitamins, if needed. 

“I think the number one concern for people is that they won’t be able to get enough protein eating a plant-based diet. I also think that people widely overestimate the amount of protein they need.”

All plant foods contain the nine essential amino acids required to make up the proteins you need, and many vegetarian foods like soy, beans, nuts, seeds and non-dairy milk products have comparable amounts of protein to animal foods. 

“Ninety-seven percent of Americans meet their daily protein requirements, but only 4% of Americans meet their daily fiber requirements . I’ve never treated a patient for protein deficiency. If you eat a wide variety of foods and eat enough calories, protein should not be a concern.”

Savor the flavor of plant-based foods. 

Adopting a plant-based diet does not mean subsisting on boring, tasteless food. Shah enjoys incorporating flavorful, varied dishes from around the world, including Ethiopia, Thailand and her native India. 

To get started on your plant-forward journey:

• Start small: Start with adding a “Meatless Monday” to your meal plan and investigate one simple and delicious recipe to try each week. Once you have identified a few favorites, you can add them to your rotation and maybe go meatless one or two days a week. You can learn a few easy techniques to incorporate in many dishes, like roasting vegetables or blending quick and easy soups. 
• Change your plate proportions: Instead of giving up your meat-based protein completely, try to reduce the space it takes on your plate. Instead of a quarter-pound sirloin steak or a full serving of roasted chicken, try a vegetable-heavy stir-fry with a few slices of beef or a salad with chicken. Once your palate and mindset have adjusted to the smaller quantity of meat, try replacing it occasionally with plant-based proteins like tofu, seitan or beans.  
• Be prepared when dining out: If possible, try to examine the restaurant menu ahead of your meal, so you’ll arrive with a plan of what you can eat. Ask for the vegan options and don’t be afraid to request substitutions or omissions for your dish. Fortunately, with more people choosing a vegetarian lifestyle, many restaurants now provide tasty, meat-free options to their customers. 
• Share a dish: Bring a dish to share at a party or potluck; this will lessen your worries about food options. Let your host know ahead of time that you are planning on bringing a dish or, if that is not possible, be upfront and find out if any modifications can be made to accommodate your preferences. Often a simple solution can be found with a little advanced planning.
• Accommodate family members: It can be tricky when one family member is ready to commit to a new diet and lifestyle while others are not. Shah recommends approaching this situation compassionately and allowing for flexibility, if possible. Hopefully your family will be willing to support you even if they are not ready to make the same commitments. Communication is key, and Shah says that the conversation is over the minute someone feels judged, so try to look for points of compromise to reach an amicable solution. 
• Feeling satisfied: A diet of nothing but lettuce and vegetables will leave you feeling hungry and unfulfilled. Be sure to bulk up your meals with filling, fiber-rich whole grains, plant-based proteins and healthy fats. Plant-based meat substitutes like Beyond Beef, seitan and veggie burgers can also be a satisfying choice when you are craving your favorite meat-based comfort food.

Remember that small, consistent changes can add up to big benefits for your health and the planet. Treat yourself and others with compassion as you embrace this new lifestyle, and take time to enjoy the different flavors and textures you discover in your journey.

“It is a really delicious, healthful, sustainable and compassionate way of eating. It doesn’t have to be perfect. Just start simply, do what feels comfortable for you and your family, and don’t forget to celebrate the joy of eating and connection around food.” 

Dr. Reshma Shah will be teaching a plant-based online cooking class with Healthy Living this summer on Tuesday, July 13, from 4:00 – 5:30 p.m.

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6518108/
• https://www.sciencedirect.com/science/article/pii/S2212371713000024 
•  https://www.portland.gov/water/water-efficiency-programs/save-water-home 
•   https://water.usgs.gov/edu/activity-watercontent.php  
• https://www.ewg.org/meateatersguide/a-meat-eaters-guide-to-climate-change-health-what-you-eat-matters/reducing-your-footprint/)  
• https://www.aspca.org/about-us/press-releases/aspca-research-shows-americans-overwhelmingly-support-investigations-expose 
•  https://www.sentienceinstitute.org/us-factory-farming-estimates
•  https://pubmed.ncbi.nlm.nih.gov/19562864/ 
•   https://www.ars.usda.gov/ARSUserFiles/8040053 0/pdf/0102/usualintaketables2001-02.pdf

I’m vegan, but sometimes I eat meat: What is happening to veganism?

The movement is torn between upholding a strict posture against the consumption of living beings and incorporating people with a plant-based diet who have the odd piece of cheese.

Veganism is on the rise. We are surrounded by vegan substitutes for milk, shampoos, donuts and tacos . In January, Kentucky Fried Chicken launched a vegan version of its battered chicken, which consists of a mixture of mushrooms with 11 types of herbs and spices. However, something doesn’t add up: vegans and vegetarians represent a tiny fracture of the general population. What’s behind this imbalance?

Being vegan is a challenge. We live in a meat-based society, which has given risen to carnism, a term coined by U.S. social psychologist Melanie Joy to describe a world where meat is the norm and included in most menus. Another difficulty is humans don’t like to stand out: we tend to follow the behavior of our social group, according to Canadian social psychologist Steven Pinker. That’s why giving up meat can be especially hard.

In Justice for Animals, renowned U.S. philosopher Martha Nussbaum writes that she eats fish because she believes that fish do not develop life plans and killing them painlessly, if they have lived in freedom, is not reprehensible. “I’m less worried about doing this than consuming 70 grams of protein daily to stay healthy at my age (73). It is something I question myself about and with which I am not satisfied, but it is the point I am at.”

The truth is that a large number of people feel uncomfortable ordering a separate meal, or bringing their own vegan food to a family gathering. Not to mention turning down their grandmother’s homemade, butter-filled cookies. As a result, a high percentage people who start a vegetarian or vegan diet end up abandoning it. Activism has its limits. In 2014, Faunalytics surveyed 11,500 consumers in the United States and Canada who were starting a vegan or vegetarian diet and found that, within six months, 84% of them had given up.

In 1980, the main reason for going vegan was animal welfare, but today, the leading reasons are for personal health and the environment. And this, for some activists, has many implications. “The difference is that one is altruistic and other is less so,” says Nuria Almirón, a Spanish activist, researcher and professor in the department of communication at the Pompeu Fabra University. “The latter have very weak ethics. Helping others is what gives you inner strength. Many people believe that they are taking the step out of genuine concern for the environment, that they are doing it for the planet, but in reality they are doing it because they are very scared to think that all of this, and our lives, is going to end. There is a self-centered component.” Almirón adds that the meat sector lobby uses “fear tactics,” addressing health concerns that also scares people off veganism.

Estela Díaz Carmona, a Spanish lawyer, has been vegan since she was a teenager. When she started to take an interest in veganism, she immersed himself in the works of philosophers such as Peter Singer, the author of the groundbreaking book Animal Liberation (1975) and Tom Regan ( The Case for Animal Rights ). She was trying to understand the reasons for our tendency towards speciesism, which discriminates against animals because they are considered inferior species to us.

Later, inspired by her activism, she decided to study eating behaviors. “I came across consumers who stated: ‘I’m vegan, but sometimes I eat cheese.’ But that’s not being vegan!” Before, says Díaz Carmona, activists were steeped in the foundations of veganism. Now there is much more “confusion,” she says “Veganism is the dietary manifestation of an ethical struggle. It is a political-moral movement and we are supposed to be part of this current. I don’t understand why some people do not understand that this is not being vegan.”

In 2016, the Spanish consulting firm Lantern decided to start studying vegans. So far they have presented four reports. In 2021, they concluded that there was “a tsunami” of veggie consumers. This “veggie” label includes vegans, vegetarians and flexitarians — people who largely consume vegetables and legumes, but who also eat meat, including red meat, between two and four times a month. Based on their survey, carried out between 1,000 and 1,200 people, there are around 4.5 million veggie consumers in Spain, of whom 9% (3.5 million) are flexitarian. This trend is seen across the Western world: in the United States, for example, it is estimated that 15% of the population is flexitarian. “If we only talked about vegans and vegetarians we would be referring to a very niche group of the population,” says Jaime Martín, the director of Lantern.

According to the surveys, young people aged between 18 and 25 are most likely to follow a plant-based diet. But interestingly, they are also more likely to eat a lot of meat as they consider it “part of their culture and their identity,” says Martín.

Given the challenges of following a strict vegan diet, there is debate in the movement about whether people who are interested in reducing their meat consumption should also be included. After seeing the high percentage rate of people giving up on veganism, Canadian activist Jo Anderson, Research Director at Faunalytics , encouraged activists to put aside a puritanism that, in her opinion, makes people feel like failures if they slip up. According to Anderson, “‘absolutism’ or ‘abolitionist’ approach to advocacy is often partly why those who try the diet slip back into eating animal products.”

In 2017, Belgian activist and strategist Tobias Leenaert published How to Create a Vegan World: a Pragmatic Approach , a work that shocked many vegan activists, who considered Leenaert “a traitor,” he explained . His message is that, in a society like ours, it is better to have a more “pragmatic” approach to veganism. In other words, if the ultimate goal is to reduce the harm against animals, there are better chances of achieving that if lots of people reduce their meat consumption, rather than if a tiny proportion of people completely cut out meat products from their diet.

The Flemish activist is in favor of accepting the aspiring vegan who’s addicted to the melted cheese on pizza, of eating the lasagna that’s accidentally been made with non-vegan pasta sheets and of witholding judgement of the vegan friend who eats sushi once a year because it’s part of a tradition they have with their uncle. “It’s easy to be a philosopher and recite truths about the rights of animals. It’s much harder to get your hands dirty and do the right things at the right time truly to make a difference,” he writes in the book. “That’s the art of high-impact advocacy.”

Melanie Joy — the creator of the concept of carnism who wrote Why We Love Dogs, Eat Pigs and Wear Cows — sees a big difference between people who are 100% vegan and those who are 99%, arguing that the latter have not embraced a vegan mindset. “Our mind is carnistic , we can’t forget that. This dominant culture is made to predominate, and veganism is a challenge to the usual diet,” she explains. “Vegans, who are the ones who oppose it, are considered emotional, problematic, sentimental, arrogant… And all these labels can be very hard to manage.” Joy lists some of the obstacles faced by vegan consumers: economic accessibility, since many meat products “are subsidized,” and the difficulty of buying fresh vegetables within a reasonable distance.

The social psychologist is not concerned that there are people who describe themselves as vegans and continue to eat meat. She believes that few vegans do this and argues that language is important. “Why are there so many feminists? In the 1970s, this word was used with pride. But there was a reaction against it and feminism became a dirty word, and we still sometimes fight against that contrary view. At first, queer was a negative word, but then it was embraced.”

Ed Winters is a young British vegan, who says that as a teenager he was a big fan of Kentucky Fried Chicken, until he saw a documentary about how chickens were dismembered — an awakening he recounts in his book This Is Vegan Propaganda.

Winters is concerned that the rise of veganism will dilute what the movement really stands for. “Meat consumption has different impacts: on our health, ethics, environmental justice... Because it has so many meanings, it can be many things to different people. I think it’s good that the word ‘vegan’ is used and seen as something normal, but the word could lose its true meaning. And while I don’t think we’ve reached the point where we need to be concerned, we are at a time where for many, vegan is not necessarily what it should be, which is ‘I want to help animals and in doing so reduce my impact on the Earth with my dietary decisions,’” he says in a video call.

According to Winters, the key to being more lenient with people who reduce their meat consumption without going 100% vegan is that it increases acceptance of veganism. Even if these consumers don’t see it as the answer needed to bring about a change in our behavior, he believes they would understand that change needs to happen for us to live in a more ethical and sustainable world. “When people realize that there has to be a change, it’s easier for them to conclude that perhaps that necessary change is veganism.”

“It is more important that all products be labeled vegan correctly than it is to label people,” says Carrie P. Freeman, a professor of communication at the University of Georgia in Atlanta, who is vegan. In an “imperfect” world like ours, you cannot be an ideal vegan, she says. But we can try to avoid animal exploitation to the best of our ability, be environmentally responsible, and want our communities and governments to make these ethical practices easy and accessible. “On my campus there was a movement asking for 50% of the menu to be vegetarian, but, unfortunately, it did not prosper. Nowadays, they only offer you one vegetarian dish on the menu. A generalized or more widespread global commitment is needed.” However, she highlights the work of the Default-Veg initiative, which seeks strategies to promote a plant-based diet.

While Leenaert may be seen as a traitor to some in the vegan movement , his approach has helped achieve something unprecedented: the Belgian government has funded a vegetarian project in the city of Ghent. Since 2009, every Thursday, the town goes vegetarian, with every restaurant offering 100% meat-free menus. Recently, the city’s public schools have joined the initiative and every Thursday, students have a meat-free menu made up of vegetables, cereals, and legumes.

According to Leenaert, we must take into account the effect that our behavior has on others. The more veganism is presented as doable and fun, rather than strict and complicated, the more people will try to be vegan, he says. “And if someone finds it difficult to follow this diet, then make an exception,” he says by videoconference from the Belgian city. “If we allow exceptions, people will want to try it. It’s that simple.”

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Vegan dog food has been hailed as the healthiest – our study shows the reality is more complicated

Professor of Small Animal Medicine, University of Liverpool

Senior Lecturer covering Veterinary Neuroscience and Neuropharmacology, University of Liverpool

Disclosure statement

Alexander German's academic position at the University of Liverpool is financially-supported by Royal Canin. He has also received research funding from the same company for projects unrelated to the current study. Finally, he has received financial remuneration and gifts for providing educational material, lecturing and consultancy work, again unrelated to the current study.

Richard Barrett-Jolley has received funding from UKRI and PetPlan. He is also currently Chair of the BBSRC funding panel "Committee A".

University of Liverpool provides funding as a founding partner of The Conversation UK.

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Two years ago, a study was published that claimed nutritionally sound vegan diets are “the healthiest and least hazardous dietary choice for dogs”.

We recently published a study challenging those findings. Based on our analysis of the data the original study used, we argue the association between diet and dog health (or more accurately, the owner’s opinion of their dog’s health) is minimal at best.

To understand why we came to a different conclusion, you need to understand how previous research on vegan dog food has been conducted and why scientists have different views on the subject.

To date, there are several published studies about the health effects of vegan dog food. Some are experimental cohort studies , where various health metrics are monitored while dogs are fed a vegan diet.

The longest was a 12-month study published in 2024, where 15 dogs ate dry dog food made from plant-based ingredients. All dogs remained healthy and there were no obvious adverse effects. However, since there was no control diet group, we cannot assume that means a plant-based diet is superior to a conventional one.

Some published studies do claim superior health for dogs fed vegan food versus other food types. However, these studies based their findings on information from owner surveys. The results from such studies rely on owner recollections and perceptions. You are studying owners’ beliefs about how healthy their dog is rather than their actual health.

The largest of these surveys , published in 2022, gathered data from over 2,000 dog owners . It included information both about the owners and their dogs, including of course the type of food the dogs were fed.

Owners were asked to recall details of their dogs’ veterinary care (such as number of veterinary visits and medication) and to report how healthy they believed their dog to be. The results of this study suggested that dogs fed a vegan diet appeared to fare better than those fed a conventional diet.

However, the statistical analyses did not explore the effect of confounding factors such as the age or breed of the dog or characteristics of the owners.

What does the new study contribute?

We conducted further analysis on the data from the original study, using different statistical techniques, effectively creating models to explain the data. We tested the effects of other owner and dog variables, as well as dog and owner diet.

For example, we looked at the owner’s age, sex and education status, and the dog’s sex, breed, age and whether they were neutered. Some statistical models also included veterinary care variables.

We found owner opinions of dog health were most strongly associated with the age of the dog: owners of younger dogs reported them to be in better health. Other variables (such as owner age, owner education and breed size) also featured in our analysis. For example, we found younger owners reported their dogs to be in better health.

Models that explained the data best of all included veterinary care variables. For example, visiting the vet more was associated with poorer owner-reported health. However, the association between vegan dog food and owner-reported health was minimal in all our models, whether or not we included the veterinary care variables. Once you take other variables into account, the effect of vegan dog food disappears.

So, why did the original study suggest a positive effect for vegan diets?

We can’t be sure but it was something we looked into. One possibility is that the survey population was unusual with many more vegan dogs than expected – 13% compared with about 1% in the general population. We also found almost all the owners that fed their dog vegan food consumed either a vegan or a vegetarian diet themselves.

This is concerning given the study findings relied on owner reports of dog health. Such recollections and responses might be influenced consciously or unconsciously by owner beliefs. If you believe that a vegan diet is best it might have an unconscious effect on perception of your dog’s health.

What does this mean?

You cannot draw a firm conclusion about what diet type is actually best for dogs from our findings. However, notwithstanding the limitations of using owner reports, there is no meaningful association between feeding vegan food and dog health. Instead, other variables are likely to be far more important.

Plus, most commercial vegan dog foods are formulated in the same way as conventional diets. Apart from only using plant-based raw materials, such vegan dog food is made by the same manufacturing processes . Many ingredients are also the same . Given such similarities, it would be surprising for one diet to give a markedly superior health on effect.

Ultimately, the most important thing for dog health is for the diet to be formulated correctly so that it meets all essential nutrient needs , according to evidence-based guidelines .

From the data published so far, no major health concerns have been identified for feeding vegan diets to dogs. However, the evidence does not suggest that there is any meaningful health benefit either.

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