Depression symptoms higher in those following vegetarian diet, study finds

Eating a vegetarian or vegan diet has been linked to increased chances of suffering symptoms of depression, according to new analysis.

Authors of the study suggest “nutritional deficiencies” could account for the “significant depressive symptoms” they discovered in participants identifying as vegetarian or vegan.

Deficiencies researchers highlighted include key fats and nutrients meat is rich in, such as Vitamin B12.

Researchers from the University of Bristol and National Institutes of Health, based in the US, made the claims after re-investigating earlier research.

Their paper is based on re-analysis of data from an older study conducted in 1992 with around 10,000 expectant fathers in Avon, Devon, of which only 350 men were vegetarians.

The paper, published in the Journal of Affective Disorders, found a statistically significant relationship between symptoms of depression and a vegetarian diet.

This stayed true even when adjusting for other factors linked to higher rates of depression, such as a family history of mental health problems, employment status and alcohol consumption.

However a more controlled investigation is needed before it can be suggested vegetarianism caused these depressive traits or vice-versa.

The original study tested male participants against the Edinburgh Post Natal Depression Scale, 18 weeks into their partners' pregnancy.

It also asked participants to report foods they ate. Men identified as vegetarian were those who had a “lower consumption of sausages, burgers, meat pies, meat, poultry, liver and white fish” and 97 per cent of the vegetarians enjoyed “green leafy vegetables”.

But the paper did show they weren’t averse to eating meat, with more than one in ten saying they would happily eat a meat pie, and at least four reporting to eating offal.

And a higher proportion of those the study identified as vegans reported eating red meat than those who called themselves vegetarians, 7.2 per cent versus 4.7 per cent.

Study authors say while a vegetarian diet is associated with improved heart health and other benefits, “little is known about the benefits or risks” of a vegetarian diet on mental health.

It concludes that diet can impact on mood in several ways, including a lack of key vitamins or fats, although these levels were not tested.

The paper says: “Since exclusion of red meat primarily characterises vegetarians, lower intakes of vitamin B12 merit consideration as a contributing factor. Our findings are also consistent with a [2014] evaluation of 1046 Australian women where lower red meat consumption was associated with nearly a doubling of risk for major depressive and anxiety disorders.”

But it acknowledges diet choice and mental health are affected by multiple factors, saying: "This study does not resolve the question of whether adoption of a vegetarian diet will increase, or decrease the risk of depressive symptoms or affect mental well-being or what specific nutrients, if any, may influence those risks, but does suggest that a randomised controlled trial of selected nutrients or foods may be warranted.”