Meat and mental health: a systematic review of meat abstention and depression, anxiety, and related phenomena

Figures & data

Text Box 1. Included psychological outcomes.

Primary outcomes

1. Depression or depressive symptoms/disorders

2. Anxiety or anxiety-related symptoms/disorders

Secondary outcomes

3. Deliberate self-harm (e.g., attempted suicide)

4. Mood/stress perception

5. Affective well-being/Quality of life (QoL)

Table 1. Summary table.

Citation and study design	Participants (sample size, population, and setting)	Psychological health outcome (description/scale/measure)	^++Definition of vegetarian sample and comparison group	Key findings
Baines et al. (2007). Public Health Nutrition, 10(5), 436–442 Cross-sectional	9113 Australian women between 22 and 27 years of age	The Medical Outcomes Study Short Form Health Survey SF-36.	Vegetarians (n = 252) excluded red meat, poultry, and fish; semi-vegetarians excluded red meat (n = 827); Non-vegetarians (n = 8034) ate red meat.	Vegetarians and semi-vegetarians had poorer mental health, higher depression and anxiety related symptoms, and greater rates of self-harm than non-vegetarians.
Bas et al. (2005). Appetite, 44(3), 309–315 Cross-sectional	1205 students from Turkey; 597 females and 608 males between 17 and 21 years (Mage = 21.3)	The Social Physique Anxiety Scale (SPAS), and the State-Trait Anxiety Inventory (STAI)	“Are you a vegetarian?” Yes/No Vegetarians (n = 31), non-vegetarians (n = 1174).	Female vegetarians scored significantly higher on the STAI than female non-vegetarians.
Beezhold et al. (2015). Nutritional Neuroscience. 2015;18(7):289–296 Cross-sectional	620 adults from USA; 487 females and 133 males between 25 and 60 years of age (Mage = 34.83)	The Depression Anxiety Stress Scale-21 (DASS)	Vegans: consumed no animal foods (n = 283). Vegetarians: consumed only eggs or dairy (n = 109). Omnivores: consumed meat, poultry, or fish (n = 228).	Vegans reported significantly lower anxiety and stress and scored significantly lower on total DASS −21 compared to omnivores.
Beezhold et al. (2010). Nutrition Journal, 9, 26 Cross-sectional	138 Seventh Day Adventists from USA 77 females and 61 males (Mage = 43.04)	DASS and the Profile of Mood States (POMS)	Vegetarians: excluded all flesh foods (n = 60); Omnivores (n = 78).	Vegetarians reported significantly better mental health (lower scores on the DASS and the POMS) than omnivores.
Beezhold and Johnston, (2012). Nutrition Journal, 11, 9 Randomized control trial	39 adults from USA; 32 females and 7 males; age not reported	The DASS and POMS	Vegetarians: avoided all animal foods except dairy (n = 13). ^++Fish eaters: consumed fish, avoided eating meat and poultry (n = 13). Omnivores: consumed meat and/or poultry (n = 13).	Vegetarians reported significantly better mood than omnivores and fish eaters after the trial.
Boldt et al. (2018). Journal of the International Society of Sports Nutrition, 15(1), 33 Cross-sectional	281 European endurance runners; 159 females and 122 males (Mage = 40)	The World Health Organization Quality of Life Assessment - Brief (WHOQLA-Brief)	Vegetarians/vegans: excluded animal products such as meat, fish, dairy products, eggs, and honey (n = 158). Omnivores: no dietary restrictions (n = 123).	No significant differences in QoL between vegetarians/vegans and omnivores.
Forestell and Nezlek (2018). Ecology of Food Nutrition, 57(3), 246–259 Cross-sectional	6450 USA undergraduate students; **3707 females and 2715 males between 16 and 47 years (Mage = 18.96)	The Center for Epidemiologic Studies Depression Scale (CES-D)	*Vegetarians: restricted all meat and fish products (n = 276). Omnivores: regularly ate fish and/or meat (n = 4955).	Vegetarians had significantly higher CES-D scores than omnivores.
Hibbeln et al. (2018). Journal of Affective Disorders, 225, 13–17 Cross-sectional	9668 male partners of English women in early stages of pregnancy; age categories (<25 to 35+)	The Edinburgh Postnatal Depression Scale	“How many times nowadays do you eat?” followed by 17 categories of foods Yes/Never Vegetarian/vegan (n = 350) Omnivore (n = 9318)	Vegetarians had significantly higher depression scores than non-vegetarians.
Lavallee et al. (2019). Journal of Affective Disorders, 248, 147–154 Cross-sectional, longitudinal	22,417 adults from Germany, Russia, USA, and China; **13,006 females and 8596 males; (Mage = 39.10)	The DASS and the Positive Mental Health scale	* “Are you currently vegetarian?” Yes/No Vegetarians: excluded meat and/or fish (n = 3400). Non-vegetarians: included meat (n = 18,603).	Cross-sectional: Vegetarian diet related to higher levels of depression and anxiety among Chinese students. Longitudinal: Vegetarian diet was predictive for depression and anxiety in Chinese students.
Lindeman (2002). Ecology of Food and Nutrition, 41(1), 75–86 Cross-sectional	308 women from Finland; age 13 to 74 (Mage = 29)	CES-D	Vegetarians (n = 42);^++Semi-vegetarians: avoided red meat or only ate fish (n = 69); Omnivores (n = 197).	Semi-vegetarians and vegetarians had more symptoms of depression than omnivores.
Matta et al. (2018). Nutrients, 10(11) Cross-sectional	90,380 adults from France; 48,035 females and 42,345 males; Age: 16 to 69 years (Mage = 42.78)	CES-D	Vegans: no consumption of animal products (n = 81). ^++Pesco-vegetarians (n = 832); ^++Lacto-ovo-vegetarians (n = 562). Omnivores: consumed all foods (n = 88,905).	The odds of depressive symptoms increased when meat was excluded from the diet. The prevalence of depressive symptoms increased with the number of excluded food groups.
Michalak et al. (2012). International Journal of Behavioral Nutrition and Physical Activity, 9, 67 Cross-sectional	4181 German adults; **2233 females and 1883 males; age: 18 to 65 (Mage = 38.87), and a socio-demographically matched subsample of non-vegetarians (n =  242)	The Munich Composite International Diagnostic Interview (mental disorder)	*“Do you currently follow a vegetarian diet (no meat) or did you follow a vegetarian diet in the past?” Answers: “no, never,” “yes, completely,” or “yes, predominantly.” ^++Vegetarians (n = 54), and non-vegetarians (n = 3872)	Vegetarians displayed elevated prevalence rates for depressive and anxiety disorders in both full and matched subsample.
Neumark-Sztainer et al. (1997). Archives of pediatrics and adolescent medicine;151(8):833–838 Cross-sectional	321 adolescents matched on age, sex, and ethnicity drawn from a larger population in Minnesota; 261 females and 60 males; age: 12 to 20 years	Health compromising behaviors assessed with a 6-point Likert-type scale ranging from never to daily. Single item: “Have you ever tried to kill yourself?”	“Are you on a special diet because of being a vegetarian?” Cross-checked with FFQ. Vegetarians (n = 107), non-vegetarians (n = 214)	Vegetarians had a greater prevalence of reported suicide attempts compared to non-vegetarians.
Perry et al. (2001). Journal of Adolescent Health, 29(6), 406–416 Cross-sectional	4746 USA adolescents; **2255 females and 2265 males; age 11 to 18 years (Mage = 14.9)	Depressive symptoms assessed on a 7-item standardized scale	“Are you a vegetarian?” Yes/No *Vegetarians (n = 262), non-vegetarians (n = 4258)	Vegetarians were more likely to think about killing themselves and “ever tried to kill [themselves]” than non-vegetarians.
Pfeiler and Egloff (2018). Appetite, 120, 246–255 Cross-sectional	Study 1: 4496 German adults; 2351 females, 2145 males; age: 17 to 96 years (Mage = 51.84) Study 2: 5125 German adults; **2669 females, 2409 males (Mage = 52.42)	Study 1 and 2: Affective well-being, life satisfaction (three and single item, respectively)	Study 1 (n1) and*Study 2 (n2): Vegans: no animal product (n1 = 13, n2 = 28). Vegetarians: no meat and avoided fish (n1 = 110; n2 = 278); meat-eaters (n1 = 4373, n2 = 4819).	No significant differences between the groups in either study on affective well-being or life satisfaction.
Stokes et al. (2011). 63. Journal of Adolescent Health, 48(2), S50 Cross-sectional	38 female adolescents meeting the DSM-IV criteria for anorexia nervosa (AN); (Mage = 16.5)	The Beck Depression Inventory (BDI) and the STAI	Vegetarians: no consumption of any form of meat (via author correspondence); Vegetarians (n = 17), non-vegetarians (n = 21);	Vegetarians with AN reported higher anxiety and trended toward higher levels of depression than non-vegetarians with AN.
Timko et al. (2012). Appetite, 58(3), 982–990 Cross-sectional	486 USA university students; **374 females and 111 males; age: 18 to 40+ years (Mage = 24.90	The DASS	Vegans: excluded animal products (n = 35). Vegetarians: ovo-, lacto- or lacto-ovo vegetarian (n = 111) ^++Semi-vegetarians: consumed no red meat or pork (n = 75). Omnivores: ate meat (n = 265)	No significant differences between the groups on depression, stress, and anxiety.
Wirnitzer et al. (2018). Nutrients, 11(1). Cross-sectional	245 endurance runners from German-speaking countries; 141 females and 104 males (median age: 37–40)	Stress perception: “Are you under pressure and/or are you suffering from stress?” Yes/No	Vegans: rejected all products from animal sources (n = 91). Vegetarians: no meat (n = 45). Omnivores: no dietary restrictions (n = 109).	No differences between the groups on stress perception.

⁺⁺ The term “semi-vegetarian” was defined differently across the studies. When the term was used to describe meat-abstainers, the group was included in our analyses. If “semi-vegetarian” included occasional meat consumers, the group was not included in our analyses.

* Discrepancies between the total sample of participants and the diet groups.

** Discrepancies between the total sample of participants and the number of males/females.

Note: AN: Anorexia Nervosa; SF: short form; BDI: The Beck Depression Inventory; CES-D: The Center for Epidemiologic Studies Depression Scale; DASS: The Depression Anxiety Stress Scale; FFQ: Food Frequency Questionnaire; SPAS: The Social Physique Anxiety Scale; STAI: The State Trait Anxiety Inventory; POMS: The Profile of Mood States; QoL: Quality of Life; WHOQLA: The World Health Organization Quality of Life Assessment.

Figure 1. PRISMA flow-chart: search results.

Table 2. Primary outcomes.

Prevalence or risk of depression and anxiety, or related symptoms
Confidence in results	*Favored meat-consumers (total n = 143,760)	No significant differences (total n = 28,893)	*Favored meat-abstainers (total n = 758)
High	Michalak et al. (2012) (Depression and Anxiety)
High	Matta et al. (2018) (Depression)
Moderate	Baines et al. (2007) (Depression and Anxiety)
Moderate	Hibbeln et al. (2018) (Depression)
Moderate	Bas et al. (2005) (Anxiety: Females)	Bas et al. (2005) (Anxiety: Males)
Moderate		Timko et al. (2012) (Depression and Anxiety)
Moderate-to-low		Perry et al. (2001) (Depression)
Moderate-to-low	Forestell and Nezlek (2018) (Depression)
Moderate-to-low	Lavallee et al. (2019) (Depression and Anxiety: China)	Lavallee et al. (2019) (Depression and Anxiety: US, Germany, Russia)
Low	Lindeman (2002) (Depression)
Low			Beezhold et al. (2010) (Depression and Anxiety)
Very low	Stokes et al. (2011) (Depression and Anxiety)
Very low			Beezhold et al. (2015) (Anxiety)
Very low		Beezhold and Johnston (2012) (Depression and Anxiety)

* Lower prevalence or risk.

Table 3. Secondary outcomes.

Prevalence or risk of self-harm, mood/stress perception, affective well-being, and quality of life (QoL)
Confidence in results	*Favored meat-consumers (total n = 36,597)	No significant differences (total n = 27,439)	*Favored meat-abstainers (total n = 797)
Moderate	Baines et al. (2007) (Self-Harm)
Moderate	Neumark-Sztainer et al. (1997) (Suicide attempts)
Moderate-to-low	Perry et al. (2001) (Suicide attempts and ideation)
Moderate-to-low		Pfeiler and Egloff (2018) (Life Satisfaction and Affective Well-being)
Moderate-to-low	Lavallee et al. (2019) (Positive Mental Health: China)	Lavallee et al. (2019) (Positive Mental Health: US, Russia, Germany)
Low		Boldt et al. (2018) (QoL)
Low		Wirnitzer et al. (2018) (Stress)
Low			Beezhold et al. (2010) (Mood/Stress)
Very low			Beezhold et al. (2015) (Stress)
Very low			Beezhold and Johnston (2012) (Stress)

* Lower prevalence or risk.

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Hibbeln, J. R., K. Northstone, J. Evans, and J. Golding. 2018. Vegetarian diets and depressive symptoms among men. Journal of Affective Disorders 225:13–17. doi: 10.1016/j.jad.2017.07.051.

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Lavallee, K., X. C. Zhang, J. Michalak, S. Schneider, and J. Margraf. 2019. Vegetarian diet and mental health: Cross-sectional and longitudinal analyses in culturally diverse samples. Journal of Affective Disorders 248:147–54. doi: 10.1016/j.jad.2019.01.035.

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