The Australian Health and Welfare Report, Australia's Health 2018, released recently highlighted that 45% of Australians will experience a mental illness at some point in their lives (1). Left untreated, mental illness can be a significant burden to bear and affect relationships, work, physical health etc.
Generally when we think of nutrition and eating well, we focus on our physical health- our risk of developing chronic diseases like diabetes, heart disease or some cancers, or maintaining a healthy body weight. But there is an emerging body of evidence that is pointing to the fact that what we eat, or don't eat, has an impact on our mental health too.
A recent study (2) by the Food and Mood Centre at Deakin University in Melbourne, the Smiles Trial, examined the relationship between food and mood and came up with some promising results for the future treatment of depression. Using a randomised control trial (the gold standard in evidence-based research), researchers recruited participants who were experiencing depression and had a low quality diet at baseline and divided them into two groups. The control group received social support for the duration of the study (12 weeks), while the intervention group received personalised dietary advice from and Accredited Practising Dietitian for the duration of the study. Both groups were assessed via a depression rating tool, the MADRS, at the commencement and conclusion of the trial. At the conclusion of the trial, participants in the dietary advice group had significantly lower scores on the depression rating tool compared to the control group, with 32% of participants in the intervention group having such a low score that they were now deemed to be 'in remission' from depression.
So what changes did the participants in the Smiles Trial make to manage such an improvement in their mental health outcomes? The focus of the personalised dietary advice involved encouraging adherence to a more traditional style of eating, involving greater consumption of the following 'healthful' foods:
* whole grains
* low-fat and unsweetened dairy foods
* raw and unsalted nuts
* lean red meats
* olive oil
And just as importantly, participants were encouraged to reduce the intake of 'extra foods' that are more common in a Western way of eating, including:
* refined cereals
* fried food
* processed meats
* sugary drinks
The results of this study back up what is seen in many observational studies around the world - depression and other mood disorders such as anxiety are less common in cultures that adhere more to a traditional diet than those with a Western diet. There seems to be something in the more plant-based, less processed style of eating that is is protective for mental health. So what exactly is it about this style of eating that is so beneficial?
There is a lot of emerging evidence in the field of nutritional science that points to the link between our gut health and our mood. Put very simply, we have a mix of both 'good' and 'bad' bacteria that reside in our intestines. Foods like wholegrain, fruits, vegetables, legumes, fish etc (the traditional-style foods that were encouraged in the above study) feed our 'good' bacteria and foods like refined cereals, fried foods, fast foods, sugary beverages etc (the Western-style foods) feed our 'bad' bacteria. When our 'bad' bacteria outnumber the 'good' we are at more risk of things like mood disorders and other chronic diseases. So eating to feed our 'good' bacteria can have a positive effect on our mental, as well as physical health.
But the realist in me knows that for many people, improving their diet quality by increasing intake of the traditional foods and reducing intake of the more Western-style of foods is a pretty big ask. Some people lack the time to prioritise health eating, others lack the education of what constitutes healthy eating, others lack the motivation, others think healthy eating is dull and tasteless. I'm sure that many of the participants in the SMILES study experienced the same, but by working with an Accredited Practising Dietitian they were able to make the required changes that saw such a great benefit to their mental health.
If you are interested in improving your diet quality to improve either your mental or physical health, please get in touch.
1. Australian Institute of Health and Welfare 2018. Australia’s health 2018: in brief. Cat. no. AUS 222. Canberra: AIHW
2. Jacka et al (2017) A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial), BMC Medicine15:23