SMILES Study: Depression and Nutrition


There is rarely a single study that definitively establishes new knowledge, but occasionally there are studies that open a window into an important new phenomenon. It is the latter type of study that was published last week in the area of nutrition and adult depression.1 The question this study asked was: In adults with depression who eat a poor diet, does teaching them about nutrition have an impact on their mental health? At the end of the 12-week intervention, the answer was: Yes, and in about 1/3 of those adults, depression symptoms dropped below threshold for diagnosis.

This study, called SMILES (Supporting the Modification of Lifestyle Interventions in Lowered Emotional States), was carried out in Australia over 12 weeks. Participants were randomized to receive either Dietary Support (DS) or Social Support (SS). To participate, they had to meet criteria for having had a Major Depressive Episode. And they also had to report on the Dietary Screening Tool that they had low intake of dietary fiber, lean protein, fruits, and vegetables; as well as a high intake of sweets, processed meats, and salty snacks.

Since everyone has an opinion of what might be the ideal diet, it is important to understand that they did not teach a gluten-free or dairy-free approach, nor Paleo or ketogenic, etc. The diet that was taught to the Dietary Support group followed a whole-foods Mediterranean approach, described as follows:

The primary focus was on increasing diet quality by supporting the consumption of the following 12 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); and olive oil (3 tablespoons per day), whilst reducing intake of ‘extras’ foods, such as sweets, refined cereals, fried food, fast food, processed meats and sugary drinks (no more than 3 per week).” 

Each participant randomized to DS received 7 hours of sessions with a dietitian. Those assigned to SS received a similar amount of time in a ‘befriending’ arrangement. There were 31 people who completed DS and 25 who completed SS.

On the primary outcome measure of depression (the MADRS), the DS group improved significantly more than the SS group, with a large effect size. And the changes in depression scores were significantly correlated with changes in diet; in other words, the people who improved their diets the most were the ones who experienced the most improvement in mood.

We are especially appreciative of the evaluation of cost provided in this article (watch for a future blog on the topic of government savings possible from embracing nutritional treatments). The estimated weekly cost of food for their participants prior to the intervention was $138AUS; the cost of the recommended diet for the DS group was only $112AUS.

One of the incidental bits of information in this article indicates the huge potential for clinical applications. They screened 166 referrals in order to find the 67 who were randomized; i.e., 99 were screened out. But what is particularly informative is that only 15 of the 99 excluded were screened out because they had a diet that was ‘too good.’ Or, to express it another way, only 15 out of 166 (9%) of a group of adults with depression met Australian guidelines for having a good diet.

Like any worthwhile study, it raises many other questions: What happened to the 2/3 who did not get much better? Would they have improved if they had been given additional nutrients in pill form? What about people who might have improved more if they had also gone gluten-free? And, importantly, what kind of results would they get if people had not been required to have such a poor quality diet to enter the study?

Finally, we want to conclude by pointing out something that may be obvious, but perhaps not. Finding that improving diet has such a dramatic improvement on 1/3 of people with depression means that poor diet is an extremely important cause of mental disorders.

Show 1 footnote

  1. 1. Jacka FN, O’Neil A, Opie R, Itsiopoulos C, Cotton S, Mohebbi M, Castle D, Dash S, Mihalopoulos C, Chatterton ML, Brazionis L, Dean OM, Hodge AM, Berk M. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med. 2017 Jan 30;15(1):23. doi: 10.1186/s12916-017-0791-y.


Mad in America hosts blogs by a diverse group of writers. These posts are designed to serve as a public forum for a discussion—broadly speaking—of psychiatry and its treatments. The opinions expressed are the writers’ own.


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  1. As an FYI, since many people develop metabolic issues from being on psych meds, eating grains (5–8 servings per day); and fruit (3 per day) would substantially spike blood sugar in alot of people even though it is considered to be “healthy” food. See

    Since extreme blood sugar spikes can cause depression, I would urge anyone who is concerned about metabolic issues to buy a glucometer and testing strips and take extensive measurements to see what foods affect you.

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    • Blood sugar spikes are responsible for a variety of “mental” symptoms. If you wanted to test yourself, the “clinical” way would be to test at hour intervals for 5 or 6(best) hours after your test meal. The medicos who routinely do this just use glucose for a standard test meal but a high carbohydrate meal may do as well, as you’re doing a rough field survey, in any case.

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    • Agree, @AA on grains and fruit. The authors come across glibly when they write, ‘…everyone has an opinion of what might be the ideal diet…’, when Integrative and Functional nutrition has clear evidence on what constitutes a better diet than the really mediocre diet shown above for the study.
      Liz Sydney

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  2. Great article! The one thing I think is missing, though, is a recognition that OF COURSE not all instances of depression are caused by poor diet or will be remediated by improved diet, because DEPRESSION IS NOT A LEGITIMATE DIAGNOSTIC CATEGORY. But we DO see that at least a third of depressed people could be dramatically improved in their mood by eating better. What is going on with the other two-thirds should be investigated, of course, but we would expect that not all of them will improve with ANY particular intervention, because DEPRESSED PEOPLE NEED DIFFERENT THINGS.

    This is vitally important, because analysis of this kind of study is dramatically hampered by the categorical clumping of depressed people into one group. This subjective grouping serves the interests of the drug companies, because they can say, “Well, nutritional counseling only helped a third of depressed patients, while antidepressants helped 45%, so antidepressants are better.” I strongly encourage you to write unequivocally on this point, as it is a very important argument to undercut any efforts by mainstream psychiatry to minimize the importance of these results.

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    • Good to see that you’ve caught on to depression as a syndrome with multiple causes. Some are: simple inadequate diet that the writers reviewed, vitamin dependencies (B1,B3,B6,B12, folate likely most common), blood sugar fluctuations, thyroid problems, metal poisoning (lead, copper, aluminum the most common), BC pills (they raise serum copper), subclinical scurvy, etc. Notice also, how few mainstream shrinks ever bother to review such things, which is why they think 50% improvement rates of medicated patients is such a great thing, while simple investigation can get 90% improvement rates, IF our shrink can pick treatments properly.

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      • Not to mention the people who are depressed because they are trapped in a dead-end job or an unhappy or dangerous marriage or kids (like me) who are forced to attend school every day for 13 years in a soul-crushing environment and have no sense of self-efficacy. Sometimes depression is not due to bad nutrition, it’s because depression is a normal expression of distress when in distressing circumstances, regardless of someone’s nutritional state.

        It is just too much work for them to figure out what’s actually going on. Much easier to blame the patient and drug them into submission!

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        • Easier than having your subject take a quantitative psych test like the HOD or EWI in the waiting room to get an idea of what they’re experiencing before you see them, in order to find out what the right questions to ask are and what you’re likely to have to do.

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          • Never heard of the HOD or the EWI. I personally never bothered with testing of any kind when I worked with people in distress. I generally found that asking them the questions instead of having a test do it for me allowed a lot more nuanced approach. The challenge is maintaining sufficient objectivity and being OK not knowing what you have to do until you get enough information. I wish there were some “objective test” but I haven’t seen one yet that even comes close. I will look into those, though.

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          • I’m not a professional therapist, so if I’ve got to do a psych-type interview, I need help deciding how to do my interview unless there’s something I can see and readily identify. If I have to do psych-type stuff, it’s generally with someone else’s treatment failures.

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  3. Doing studies to measure people’s “mental states”, is wrong. I hope people refuse to cooperate and find ways to obstruct your future studies.

    If people are depressed, its because they lead depressing lives. So the solution is to solve the problem in their lives. Psychotherapists and life coaches are not going to do this. Political and legal organizing will


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  4. A lot of children’s behaviour issues would lessen or disappear if families quit sugar (and sugar substitutes) and colourings; quit conventionally grown food in favour of organic; quit gluten and most dairy; and supplemented with good fats (coconut, grapeseed, some fish oils except that’s suspect now with ocean contaminants). But it’s a lot to ask a time-stressed family of limited means, so pharma wins the day because it’s quick, available, and convenient…just like the crap food they’re eating. And dumb health professionals are clueless about nutrition and quick with the prescribing pen, which exacerbates the problem.

    No easy answers.

    Liz Sydney

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  5. Wonderful. This study supports my hypothesis called “natural nutrition theory of intelligence.” I wrote a free ebook detailing the effects of various diets and individual foods on mental state. This ebook also describes the effects of other physiological treatments on mental state: cold and hot hydrotherapy, hot environment, breath holding, hyperventilation, physical exercise, fasting, etc., etc. The book contains over 1000 scientific references, “How to Become Smarter” Charles Spender, 2010, available everywhere. I will definitely add this study to the list of cited literature.

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  6. Many people recover from depression spontaneously without treatment, i.e. they recover with time (I believe David Healy says 80% recovers within several months, and he’s like the biggest expert on depression; the rate might be lower in this study because the patients had “major depression”, whatever that means, and the study only lasted 12 weeks). This was not taken into account here. Also, blaming gluten and dairy or the abscence of supplements for the group that didn’t get better sounds ridiculous to me. What you should look at, is whether or not they had psychological support and received some kind of therapy. That is after all still the main recommended treatment for depression, and definitely your best bet for recovery. How can you draw conclusions about the influence of diet on depression if you don’t look at other factors like therapeutic interventions?

    I am the first one to support the idea of eating healthily but I don’t like how the alternative mental health movement is trying to blame gluten and dairy for just about every problem on the planet, and how they are promoting dangerous supplements when there are is hardly any science that proves their efficacy. Mainstream psychiatry made the huge mistake of reducing mental illness to chemical imbalances, i.e. a biological problem. Aren’t you doing exactly the same with this whole gluten thing and all the “vitamin deficiencies”? I just don’t get it. Not everything is about food, and it’s certainly not gluten that is destroying the human race. Just my opinion.

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  7. Elsie,

    I definitely share your concerns about the alternative mental health movement. Pushing someone to take a “million” supplements seems no different than pushing meds.

    But having said that, I know when I don’t take enough vitamin D, I feel more depressed than usual. However, taking the right amount isn’t going to going to magically make all my problems disappear.

    I am also concerned that these authors promoted the Standard American diet of high carb, low fat that has not worked for many people, including folks with metabolic issues who have said this type of diet worsens their condition. They also don’t seem to realize that studies have shown that good fats like the ones Liz Sydney mentioned should not be avoided.

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  8. I am not familiar with the: “SMILES Study, Depression and Nutrition”.
    I looked at the food breaking (i am at Europe). That is not a Mediterranean Diet.
    You can call that a: “diet aproach based at…”, or a “variation of…”
    But is not a Mediterranean Diet. Is a variation of a America diet. But i will not argue about that, since the Mediterranean Diets of 1960 are gone. Is pointeless.

    Like has already been said, depression has many causes. And there is the natural (traditional) path of self-healing depression (in due time). And there is the pills-for-depression-for-life path.

    People familiar with diets… know that is hard to change food/dring habits.
    So, to change many things at a diet, will work? Will last.

    Fish. At the so-called “Mediterranean” of the “SMILES Study”, they ate fish:
    a) “(at least 2 per week)”;
    b) “whole grains (5–8 servings per day)”;

    And seems Japan one of the countries that has the lowest rates of depression of the world, used to be among the top fish eaters. There are grahics about that.
    Cereals and their produtcs on the other hand…

    Marine Omega 3 (daily, at a high supplement dose). Seems to help people with SZ and depression.

    And Psychiatrists usually are very ignorant about foods/ supplments. Hospital foods/drinks suck… big time.

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    • Agree @AntiP, The diet they show is only barely better than the average conventional North American diet and the authors are glib in their defense of it. People looking to significantly alter their mind/body health would do better to look to Functional and Integrative nutrition, which speak/s directly and forcefully to how food affects the gut-brain system.
      Liz Sydney

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