A strict vegetarian diet has long been scrutinized for the toll it can take on a person’s physical wellbeing, but a new scientific report raises another important question: what about a vegetarian’s mental wellbeing?

There’s a good deal of medical literature associating deficiencies of B12 and omega-3 with depression. These essential nutrients are most commonly found in meat, fish, and other animal products. So it’s not necessarily surprising to hear that vegetarianism is linked with depression.

Even so, the report details a number of worrisome findings, citing data from a compilation of surveys examining different groups in different countries but with similar findings: vegetarians are significantly more prone to depression than the omnivorous majority of the population. A sample of the findings is below.

  • A longitudinal study of 14,247 young women found that 30 percent of vegetarians and semi-vegetarians had experienced depression in the previous 12 months, compared to 20 percent of non-vegetarian women. (Baines, 2007)
  • A study of 4,116 Germans including vegetarian, semi-vegetarian and non-vegetarian people found that more vegetarians suffered from depressive disorders in the previous month, the previous year, and throughout their lifetime.
  • In a British study, 9,668 men who were partners of pregnant women took the Edinburgh Postnatal Depression Scale. Seven percent of the vegetarians obtained scores indicating severe depression compared to four percent of non-vegetarians.
  • Investigators from the College of William and Mary examined depression among 6,422 college students. Vegetarian and semi-vegetarian students scored significantly higher than the omnivores on the Center for Epidemiologic Depression Scale.

This Psychology Today article confirms the findings of the report but challenges them by citing three studies showing no meaningful difference between the different dietary groups. One concern: those three studies use significantly less people to arrive at their numbers—486, 620, and 138 respectively. Such low and unrepresentative numbers cannot be credibly compared to studies involving roughly 5,000 to 15,000 people.

The United States is currently facing an invisible but ever-present crisis of people facing depression and loneliness. 30 years ago, 1 in 50 Americans took an antidepressant medication and, as of 2014, 1 in 9 Americans do. That rate has almost doubled since 2010 and more than tripled since 2000, revealing the widespread reach of this crisis.

In 2017, 47,000 Americans took their own life, with the suicide rate increasing 33 percent between 1999 and 2017. In fact, American suicide rates are at the highest they’ve been in 50 years.

A Google search of “vegan isolation” reveals that many vegans struggle with issues of isolation, not because the diet calls for it, but because it’s a side-effect of the strict lifestyle which excludes all animal products.

The correlation of vegetarianism and depression is cause for concern. Additional and better research is needed to shed more light on this critical issue.