According to a new meta-analysis published in the journal Critical Reviews in Food Science and Nutrition, compared to meat abstention, meat consumption is associated with lower levels of depression and anxiety.
In 2017, mental illness was considered to be the leading cause of disability globally. The World Health Organization estimated that approximately 300 million people suffered from depression, and 260 million were living with anxiety, reflecting a considerable increase in these disorders over the past two decades. In parallel with the observed increases in mental disorders, vegetarianism and veganism are becoming more prevalent. Motivators for this dietary choice include ethical, environmental, and animal rights-based concerns, as well as attempts to improve mental health via diet.
“My interest was driven by the dramatic surge in both restrictive dieting (e.g., veganism and vegetarianism) and mental illness over the past two decades,” explained study author Urska Dobersek, an assistant professor at the University of Southern Indiana. “Our previous systematic review was qualitative (Dobersek et al., 2020) and the natural next step was to show a quantitative relation between meat and mental health.”
Dobersek and colleagues extracted data from 20 existing studies, including cross-sectional and longitudinal studies, as well as randomized control trials. In these studies, depression and anxiety were assessed through self-report ratings, the use of prescription medication, a medical diagnosis, or diagnostic interview. A total of 171,802 participants between ages 11 to 105 were included in this meta-analysis, of which, 157,778 identified as meat consumers while 13,259 identified as meat abstainers. Participants’ geographic locations included Europe, Asia, North America, and Oceania.
The researchers found that individuals who consumed meat experienced lower levels of depression and anxiety compared to individuals who abstained from meat. Vegans were found to experience greater levels of depression compared to meat consumers. Participants’ sex did not explain these associations. Further, the analyses revealed that the more rigorous studies were (i.e., relying on physician-diagnosed mental illness as opposed to self-report questionnaires), the stronger the observed benefits of meat consumption.
The findings suggest that “restrictive diets are unhealthy and may lead to unhappiness in the long-term,” Dobersek told PsyPost. “The idea that we can become healthier (or happier) by eliminating foods and beverages is simplistic, unscientific, and not supported by valid evidence.”
“Dietary restrictions are the antithesis of eating a varied (read: Healthy) diet. It makes no sense to tell people to eat a “varied” diet followed by a laundry-list of things they shouldn’t eat and drink! The best advice is to eat everything in moderation, exercise daily, and do the things that make you happy.”
This work has several strengths, including its large sample size, and criteria to include only studies that provided a clear dichotomy between meat consumers and meat abstainers.
However, the researchers note a few limitations. This meta-analysis only included studies that were published in English, which could bias the results toward Western norms. Excluding papers in other languages (such as Hindi), could have omitted studies that were conducted in regions that follow predominantly vegetarian or plant-based diets. As well, despite the observed link between meat consumption and mental health, these results prevent inferences about the temporal order of these variables and causal conclusions.
“As always, correlation does not imply causation,” Dobersek explained. “For example, individuals struggling with mental illness may alter their diets as a form of self-treatment; yet vegan and strict vegetarian diets may lead to nutrient deficiencies that can actually increase the risk of mental illness.”
“Additionally, many individuals with eating disorders use veganism and vegetarianism as a ‘cover’ to hide their illness; and individuals who are extremely sensitive to the suffering of animals may also become both vegetarian and depressed/anxious as a way to help alleviate this suffering.”
Despite the limitations, Dobersek said that the findings “provide further evidence that because humans are omnivores, it is illogical and potentially unhealthy to recommend restrictive diets to non-clinical populations.”
The meta-analysis, “Meat and mental health: A meta-analysis of meat consumption, depression, and anxiety”, was authored by Urska Dobersek, Kelsey Teel, Sydney Altmeyer, Joshua Adkins, Gabrielle Wy, and Jackson Peak.