It is widely accepted that what we eat has a large impact on our physical health. There’s not many of us would argue otherwise.
However, it is not until relatively recently that it’s become more widely appreciated that what we eat also plays a major role in influencing our mood and mental wellbeing, both in the short and long term.
One of the first scientific trials to investigate the link between diet and mental health was the SMILES trial (Supporting the Modification of lifestyle in Lowered Emotional States).
The SMILES trial was the first intervention study to investigate the effect of dietary improvement on people living with depression compared to a control group living with depression who did not receive dietary intervention.
It is 3 of the key findings from this trial that I’d like to share with you in this post because these findings are important.
Actually, these findings are incredibly important and yet as with any advancements in scientific understanding there is a delay between the evidence and the translating to uptake of the information in the teaching and crucially using of this information in day-to-day healthcare practice.
Therefore, it is my hope that after you read this post and understand these 3 key findings from the SMILES trial you can use your knowledge to begin to make your own decisions whether dietary changes may be worth considering as part of your own or someone you care abouts treatment for depression. Or possibly a place worth investigating as a means of improving your mental wellbeing overall and without your necessarily having to be currently suffering from clinical depression.
Before I share these 3 key findings from the SMILES trial, I want to quickly give you some essential context to the SMILES trial to help you understand what it all means…
The SMILES Trial in a Nutshell
The SMILES study was the first randomised controlled trial (RCT, parallel-group single blinded) of its type.
The trial included 67 participants over the age of 18 who met the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV-TR) diagnostic criteria for a major depressive episode (MDE), scored 18 or over on the Montgomery–Åsberg Depression Rating Scale (MADRS)1 and scored 75 or less, out of a possible score of 104, on a Dietary Screening Tool (DST)2 modified for Australian food products. The participants were assigned to two groups;
Group 1 (33 participants) who received personalised dietary advice, nutritional counselling and support, including motivational interviewing, goal setting and mindful eating from a clinical dietitian (APD)
and
Group 2 (34 participants) who received social support in the form of a trained person engaging in either a discussion about topics of interest to the participant and/or playing board or card games with the intention of keeping the participants engaged and in a positive mood.
The trial ran for 12 weeks (3 months) in which time both intervention groups received either 7 dietitian consults or 7 social support sessions of approximately 1hr each. The first 4 sessions occurred weekly and the following 3 were fortnightly.
My Take on the 3 Key Findings from the SMILES Trial
Key Finding #1
The results of the study showed the people who were in the dietary change group had a statistically significant reduction in their depressive symptoms compared to those who were in the group who received social support without dietary intervention.
At 12 weeks 32.3% of those in the dietary support group compared to 8% of those in the social support group met criteria for remission of major depression3.
Key Finding #2
The improvements in depressive symptoms were not linked to weight changes (or self-efficacy, quitting smoking and/or changes in physical activity levels).
The trial clearly showed the beneficial effects dietary changes in and of themselves have on mental health irrespective of whether or not these changes influence anything physical.
In my line of work as a dietitian I often receive referrals from general practitioners for patients who have tried weight loss diet after weight loss diet in the name of “health” and I think this Key
Finding #2 is such an important one to consider if you’ve ever had a thought along the lines of “well my weight doesn’t change even when I eat well, so what’s the point?”
The point is while your weight may not change when you eat well but your health does.
The point is your weight may not change when you eat well but your wellbeing and enjoyment of life does.
And that is more important than the number on the scale.
Key Finding #3
The cost of eating the mood improving diet was not higher than the cost of the food participants was purchasing before they began the trail.
It is a common stance that eating “healthy” is more expensive that not eating “healthy”. I certainly understand where this comes from especially if you live in a remote location where access to foods is limited and prices higher of those which are more perishable (for example fresh fruits and vegetables).
However, as a dietitian and having the understanding of what it truly means to eat “healthy” it is in reality often very affordable, and this is what the SMILES trial found. Why? Because when it comes to real and true “healthy” eating this does not include expensive powders and potions, it simply means choosing the majority of your foods from the core food groups (grains, meats and alternative, dairy and alternatives, fruits and vegetables).
Now that you’ve read my summarised take on what I believe are some of the key findings from the SMILES trial you may be intrigued to know what exactly was this diet the participants went on and what was it about this special mood improving diet which made it so great for mental health?
What Exactly Was This Mood Improving Diet?…
The mood improving diet was called ‘ModiMedDiet’ and was based on the Australian Dietary guidelines and the Dietary Guidelines for Adults in Greece.
It didn’t include any special supplements or specific “health food” products. The focus was simply on increasing diet quality by encouraging the consumption of the following 11 key food groups (recommended servings in brackets).
- Whole grains (5–8 servings per day)
- Vegetables (6 per day).
- Fruit (3 per day).
- Legumes (3–4 per week).
- Low-fat and unsweetened dairy foods (2–3 per day)
- Raw and unsalted nuts (1 per day)
- Fish (at least 2 per week)
- Lean red meats (3–4 per week)
- Chicken (2–3 per week)
- Eggs (up to 6 per week)
- Olive oil (3 tablespoons per day)
While simultaneously encouraging a decreased consumption of “extras” including sweets, refined cereals, fried food, fast-food, processed meats and sugary drinks (3 or less per week). Red or white wine consumption beyond 2 standard drinks per day and all other alcohol (e.g. spirits, beer) were included within the “extras” food group.
For anyone who is interested in the macro composition of diets the dietary composition of the ModiMedDiet was: protein 18% of total energy (E); fat 40% of E; carbohydrates 37% of E; alcohol 2% of E; fibre/other 3% of E.
The diet was designed to be easy to follow, sustainable, palatable, and satiating.
Participants did not have amounts in terms of calories or serving sizes they had to eat but rather ate ad libitum (as they pleased).
How Does What We Eat Affect Our Mental Health?
While we may not know the exact intricacies, we do know there are countless ways in which what we eat affects our mental health, mood and wellbeing.
Some of the ways improving diet is suggested to play a role in improving depressive symptoms include preventing inflammation and oxidative stress pathways, as well as enhancing brain plasticity (neurogenesis and neuroplasticity) and promoting beneficial changes in gut microbiota. For more specific details of just how diet affects our mental health and how you can use this to improve your mood and mental health click on these links to read my earlier posts 5 Simple Tips on How to Eat to Boost Your Happiness, Can Curing Depression Be As Simple As Eating Better? 4 Often Overlooked Nutritional Deficiencies Which Can Cause Depression and Can Nutrition Help Depression?
In addition to the direct role the chemical components within the types of foods we consume have on our bodies improvements in behaviours associated with food such as cooking, shopping and meal patterns evidently are likely to have a therapeutic benefit and were all included within the SMILES intervention.
Take Away Tips
The SMILES trial showed what we eat can improve our mental health, including remission from major depression, that this improvement in mental health and mood is irrespective of weight loss or other physical changes and that eating a mood enhancing diet need not be expensive.
Since the results of this pioneering study were published there have been a number of studies to follow which have duplicated the results. That is, they’ve also shown the achievement of great improvements in depressive symptoms of participants when they underwent a period of dietary improvement, including the HELFIMED study4.
Based on the conclusions drawn from the SMILES trial and others like it, it becomes easy to see that diet is central to our mental health and wellbeing.
Diet can be used as an effective and relatively fast acting therapeutic tool.
By no means am I saying diet is the be all and end all of mental health and that improving your diet will always result in improvements in mental health but at the end of the day what we eat is clearly a stepping off point from which all else, including our mental capacity follows. We are biological beings and as such will always be limited by our biology.
The SMILES trial and others like it collectively advocate for the addition of dietitians (APDs) to mental health care teams (the only mental health conditions for which sufferers currently receive Government assistance with funding for dietetic treatment are eating disorders).
Given the rapidly growing evidence that what we eat can so drastically affect our mental health these advocations are worth considering as a first line of treatment.
I want to make it abundantly clear at this point that I am advocating for your or your loved one to work with a clinical dietitian if your goal is to enhance your mental health through dietary changes and not simply knowing diet is important and taking dietary changes into you own hands or jumping into the advice of this or that person on YouTube or Instagram. Because just as dietary changes can greatly improve mental health when done correctly, they have the potential to cause just as devastating effects when done incorrectly.
The SMILES trial did not show remission from clinical depression in people who drastically changed their diet based on something they Googled on the internet. It found a high percentage of people achieved remission from clinical depression with the support of a trained professional in human nutrition. There is a big difference between the two. Moral of the story: if you found this blog of interest and are intrigued to know whether you or a loved one may be able to experience any meaningful change in mental health and mood through adjusting what you eat please work with a clinical dietitian.
This is too important an area with too much potential to go right and too much potential to go wrong to give DIY a crack.
With my whole heart I hope you found this information useful and inspiring.
Become Great. Live Great.
Bonnie.
Reference
- Montgomery SA, Asberg M. A new depression scale designed to be sensitive to change. Br J Psychiatry. 1979;134:382–9.
- Bailey RL, Miller PE, Mitchell DC, Hartman TJ, Lawrence FR, Sempos CT, et al. Dietary screening tool identifies nutritional risk in older adults. Am J Clin Nutr. 2009;90(1):177–83.
- Jacka, F.N., O’Neil, A., Opie, R. et al.A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med 15, 23.
- Parletta N, Zarnowiecki D, Cho J, Wilson A, Bogomolova S, Villani A, et al. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression: a randomized controlled trial (HELFIMED). Nutr Neurosci. 2017.
