Research: Meat and Mental Health

Meat-free diets, including veganism and vegetarianism, have become increasingly popular over the past decade. Between 2014 and 2019, the number of British individuals identifying as vegan quadrupled and of these, 50% were aged 15 and 34 years old and 63% identified as female. A vegan lifestyle is now protected under the scope of international human rights in the UK, which means we have a collective responsibility to respect the choice of those wanting to adhere to a vegan lifestyle, as well as avoid discriminating against anyone who chooses to do so. Before we go any further, we just want to acknowledge the privilege of being able to choose a certain dietary style that not all are afforded.

Some of the motivations behind the rise in meat free diets include concern for animal welfare, the environment, trends promoted by the media and social media as well as for “health” reasons.

 When it comes to plant based diets, you don’t have to look too far for the plethora of associated “health” benefits including lowering cholesterol, reducing blood pressure and protecting against cancer.  At the same time, it’s hard to know if it’s the absence of meat, or the addition of plant based foods rich in fibre, antioxidants and phytonutrients, that may underpin these benefits. We are certainly not going to argue about the benefit of adding in diversity to our diets, including a variety of plant foods, however, is cutting out meat really the best way to improve your health?

Potentially not. Some studies have shown that not consuming meat is linked to poorer mental health and wellbeing when compared to those following a meat inclusive diet. In 2017, The World Health Organisation declared that mental illness was the main cause of global disability and it’s estimated that around 280 million people worldwide experience depression.

The emerging field of nutritional psychiatry has already explored links between our diet and mental wellbeing. The most well-known trial is the SMILES trial conducted by Professor Felice Jacka which found that a 12 week dietary intervention was more effective at improving symptoms of moderate to severe depression than a social support befriending service. The SMILES trial was the first randomised control trial which showed that dietary intervention, with clinical guidance from a nutrition professional may be an effective, accessible and affordable treatment for depression.

The current study aimed to explore the relationship between consuming or avoiding meat and how this may impact psychological health and general wellbeing.

Method

A systematic review including 18 academic papers with information from over 158,000 participants was gathered. Around 150,000 of these participants were meat eaters and around 8,000 were non-meat eaters. The researchers were investigating the following primary and secondary outcomes:

• Primary outcomes: Anxiety and depression

• Secondary outcomes: Self harm, mood and stress and quality of life

Each paper was ranked from most rigorous to least rigorous according to its methodology as this had an impact on the outcome of results.

Results

• The most rigorous study found non-meat eaters to be 15% more likely to have depression compared to those who were eating meat.

• The same study also revealed that prevalence of anxiety in non-meat eaters was over twice that of those who consumed meat.

• Non-meat eaters were over three times more likely to self-harm and twice as likely to attempt suicide than those who ate meat.

• Better mood states and lower stress levels were linked to not consuming meat.

• No differences in quality of life between meat eaters and non-meat eaters were found.

Limitations

• All studies used self-reported dietary intake methods which are subject to bias.

• Studies which were not conducted in English were excluded from this study and therefore the results may be biased towards more Western norms, one of which includes the greater consumption of meat.

• Inferences made using these results are only as accurate as the original data collected and given the huge variation in the methodological rigor of the studies included, caution must be taken when drawing definitive conclusions from these results.

Conclusion

Most of the studies included, particularly the ones that were of a higher quality, highlighted that that non-meat eaters were at a significantly higher risk for depression, anxiety and self-harm related behaviours. However, we must be mindful that this does not indicate a causal relationship between the avoidance of meat and psychological outcomes, but rather a correlation. 

 Some plausible mechanisms behind this link may include nutritional deficiencies, such as omega 3, an essential fatty acid predominantly found in oily fish, vitamin B12, both of which are  components of optimal cognitive functioning and mental wellbeing. Other nutrients which tend to be higher or more bioavailable in meat based products and play a role in mental wellbeing include iron, zinc and selenium.

Whilst it is absolutely possible to obtain a full nutrient profile through a vegetarian or vegan diet, the latter of which will require some supplementation, one certainly has to put in a little bit more effort. With the popularity of veganism in particular, many are switching without proper education.

Moreover, many plant based alternatives of popular foods do not mimic the nutrient profile of the meat alternative, as demonstrated in a 2021 study comparing meat products and plant based equivalents. Researchers found that many metabolites which play important roles for both cognitive and physiological functioning, were found exclusively or in much higher quantities in the grass-fed beef compared with the plant based alternative. These metabolites included essential omega 3 fatty acids, such as DHA, and vitamins including iron and zinc. Interestingly, phytosterols and tocopherols, both known for their antioxidant and anti-inflammatory properties, were found in greater abundance in the plant-based meat alternative, supporting the study’s conclusion that a combination of both red meat and plant-based meat alternatives would be nutritionally complementary. At Isa Robinson Nutrition, we are all about all foods fit!

It is also important to acknowledge that diet is not the only factor which impacts our mental health. Many of the studies included did not account for other influences, for example, disposable income, exercise habits, smoking and alcohol intake, social class, history of trauma or adverse childhood experiences (ACEs). Between 2012 and 2017, mental illnesses such as anxiety and depression, were found to be the largest ACE-attributed cost in England and Wales at £11.2 billion per year. The World Health Organisation has estimated that 30% of mental illness seen in adults across 21 countries may be due to ACEs. Therefore, future studies are needed which control for these variables.

Some individuals avoid meat consumption due to higher costs. Given the rise in cost of living and food prices, poor mental health may be linked to increase psychological stress associated with the social determinants of health, rather than meat or no meat. We know the social determinants of health play a much greater role in the overall picture of wellbeing when compared to factors such as diet or exercise.

In addition, avoiding consumption of animal products through dietary styles such as veganism and vegetarianism have been associated with masking eating disorders and orthorexia. Individuals who are undernourished, albeit from food poverty or an eating disorder, are at great risk of anxiety, depression and poor mental wellbeing.

When it comes to meat and mental health, the jury is still out on the exact link and more studies are needed.

In summary, whilst the findings from these studies are interesting, mental health is a complex and multifactorial topic. It is too simplistic to suggest that consuming meat or not consuming meat is the difference between having good mental health or struggling with mental health. Undoubtably there are positives and negatives associated with a meat-free diet, therefore it is important to find what works for you and not to feel pressurised into changing what you’re eating based upon the influence of others around you. One thing we would like to hold, is that meat often gets a bad rep, and we know many of our clients often fear meat based products due to lots of the media headlines that paint this as a somehow “bad” food. On the contrary, all foods fit and as we explored, meat contains plenty of nutrients, it can also be part of traditional cuisines, family favourites, social eating and tastes delicious.

We invite you to check in with your intentions in following any particular dietary style to ensure it’s coming from a positive place and one that allows you to feel freedom, flexibility and joy in eating, rather than feeling restricted or punished.