A review of 18 studies examining the relation between the consumption or avoidance of meat and psychological health concluded that people who avoid meat had significantly higher rates or risk of depression and anxiety.

The new research published in Critical Reviews in Food Science and Nutrition¹ found one in three vegetarians suffer from depression or anxiety in their lifetime and compared to meat-eaters, vegetarians were two times more likely to take prescription medications for mental illness.

“Vegetarian” can be a fuzzy term. To avoid confusion, the researchers only examined studies that provided a clear distinction between meat eaters and those who abstained from meat. Data was collected from 160,257 participants in Europe, Asia, North America, and Oceania.

The authors undertook the rigorous systematic review given the dramatic surge in veganism and mental illness over the past two decades, as a necessary first step in examining the relations between meat and mental health. ‘What we eat’ and ‘how we eat’ are integral parts of our identity and directly influence our physical, social, and mental health.

The authors were truly surprised at how consistent the relation between meat-avoidance and the increased prevalence of mental illness was across populations. The researchers found clear evidence that those who abstained from consuming meat tended to have higher rates or risk of depression, anxiety, and self-harm compared to those who did not. Less clear was how meat consumption was related to stress perception and quality of life.

Since correlation does not imply a causal relationship, the authors suggested:

• that individuals struggling with mental illness may alter their diets as a form of self-treatment;
• vegan and strict vegetarian diets may lead to nutrient deficiencies that increase the risk of mental illness;
• many individuals with eating disorders use veganism and vegetarianism as a ‘cover’ to hide their illness; and
• individuals who are extremely sensitive to or focused on the suffering of animals may become both vegetarian and depressed or anxious as a result.

These findings have implications when defining what constitutes a ‘healthy diet.’ Mental health may need to be emphasized when evaluating the benefits and risks of particular dietary patterns.

¹ Urska Dobersek, Gabrielle Wy, Joshua Adkins, Sydney Altmeyer, Kaitlin Krout, Carl J. Lavie & Edward Archer (2020) Meat and mental health: a systematic review of meat abstention and depression, anxiety, and related phenomena, Critical Reviews in Food Science and Nutrition, DOI: 10.1080/10408398.2020.1741505