Is there a connection between meat consumption and mental health?

A review of primary research examining psychological health and well-being and consumption or avoidance of meat has thrown up some interesting conclusions, and it might just have you reaching for a chicken sandwich or similar.

A review of literature comprising over 160,000 participants aged 11-96 from four continents and published in Critical Reviews in Food Science and Nutrition reveals clear evidence that not eating meat is associated with higher rates or risk of depression, anxiety and self-harm.

The role of meat?

There has been a lot of research into the benefits and drawbacks of eating, or not eating, meat yet, taken as a whole, published studies can be quite contradictory.

Meat provides a range of essential nutrients and bioactive substances, yet some reports have said that avoiding it can be beneficial and that vegetarian diets can prevent and treat disease.

Other studies have suggested  there is a reduction in mortality associated with vegetarianism, however there is a larger body of evidence that suggests that the benefits associated with vegetarianism may not be due to the avoidance of meat per se, but instead due to other lifestyle changes.

The inconsistent and contradictory nature of studies to date is what prompted this latest piece of research, its authors hoping to identify outcomes, strengths, and limitations in the scientific literature on the relationship between mental health and meat.

From all of the available literature available online, only 18 studies were found to meet their inclusion criteria for review. Of the the people included in the published studies, 149,559 were meat eaters, while 8,584 were meat abstainers.

Association

Eleven of these studies demonstrated that not eating meat was associated with poorer psychological health. Four studies were equivocal, and three studies found that meat abstainers had better outcomes.

When looking at the most rigorously conducted studies, all showed that the prevalence or risk of depression and/or anxiety were significantly greater in those participants who avoided eating meat.

If you are wondering why the researchers focused on only a small sample of all of the published literature, there were a number of factors that needed to be considered.

What, for example, is vegetarianism? For some, it is not abstaining from all meat, but simply from red meat, for example, so the researchers narrowed their focus to include only studies where vegetarians were defined as not consuming any meat at all. A number of other criteria, such as how rigorously research was conducted, were also applied.

The researchers note that that those who abstained from meat consumption had a greater risk or prevalence of depression, anxiety and self-harm. However, they point out that meat avoidance may simply be a behavioral marker that signifies poorer mental health.

Study designs and/or a lack of rigor in studies preclude inference of causal inference and none should be inferred, however, they add, the study does not support avoiding meat consumption for overall psychological health.