SMILES diet depression trial: reduced depression and anxiety

The SMILES trial, A randomised controlled trial of dietary improvement for adults with major depression was recently published BMC Medicine. It is the first randomized controlled trial to test whether dietary improvement can actually treat depression. Yes, we’re using dietary improvement and treat in the same sentence!

The objective was to determine if “structured dietary support, focusing on improving diet quality using a modified Mediterranean diet model” would have an impact on mood. The outcome is very exciting:

‘SMILES’ was a 12-week, parallel-group, single blind, randomised controlled trial of an adjunctive dietary intervention in the treatment of moderate to severe depression. The intervention consisted of seven individual nutritional consulting sessions delivered by a clinical dietician. The control condition comprised a social support protocol to the same visit schedule and length.

The results indicate that dietary improvement may provide an efficacious and accessible treatment strategy for the management of this highly prevalent mental disorder, the benefits of which could extend to the management of common co-morbidities.

These encouraging results were seen in participants who switched from a junk food diet to a real foods diet. Of the 67 who were enrolled in the study, the majority were using some form of therapy: psychotherapy and medications combined or psychotherapy only or medication only. There were 31 in the diet support group and 25 in the social support control group. Participants had to have been eating this diet in order to be accepted into the study:

a poor (low) intake of dietary fibre, lean proteins and fruit and vegetables, and a high intake of sweets, processed meats and salty snacks.

The dietary approach followed by participants in the study intervention group was the ‘ModiMedDiet’ which is based on the Australian Dietary guidelines and the Dietary Guidelines for Adults in Greece.

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). 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. Individuals were advised to select red wine preferably and only drink with meals.

The dietary composition of the ModiMedDiet was as follows: protein 18% of total energy; fat 40%; carbohydrates 37%; alcohol 2%; fibre/other 3%.

Here are the reasons I’m excited about this research:

• It’s the first randomized controlled diet depression study and ONE THIRD of the dietary intervention group saw improvements in their depression symptoms.  This was just diet alone and switching from processed/junk food to real food with no specific dietary restrictions!
• Participants also reported improvements in anxiety symptoms.
• The authors even addressed the cost factor, stating it was more affordable to eat this way ($112 per week vs $138 per week).
• The authors address the fact that the dietary intervention group was able to make these dietary changes “despite the fatigue and lack of motivation” that we so commonly see with depression.
• I’m optimistic about it paving the way for making dietary approaches part of the standard of treatment for mental health conditions. The paper suggests the addition of “clinical dieticians to multidisciplinary mental health teams.”  I’d like to add that these dieticians, together with nutritionists and health coaches would need to be well versed in functional medicine approaches.
• According to an article on ABC, one participant continued the Mediterranean diet after finishing the study and is now doing a diploma in health science. How inspiring is this? When we get results like this we want to share them with everyone!  

These are very encouraging results and we applaud the positive results of this SMILES study which are truly groundbreaking.

Let’s also be aware of where we are headed with future research and how we can improve on the trial diet.  The researchers conclude with this comment about future research:

The scaling up of interventions and identification of the pathways that mediate the impact of dietary improvement on depressive illness are also key imperatives

Professor Jacka recently shared this paper on how personalized dietary interventions successfully lower post-meal glucose i.e. how certain foods can affect two people quite differently because of our unique gut bacteria. She said that she wants to do a similar personalized nutrition study for depression if they are successful in obtaining NHMRC funding.

Here are some questions I’ve been asked about this SMILES trial (and I’m sharing here in case you have similar questions):

• why did only one-third of the study intervention group see improvements?
• why was wheat and other grains included?
• why was low fat dairy and lean meats emphasized?
• why was there no mention of grass-fed meat, wild fish, healthy fats like butter and coconut oil, pastured eggs or chickens or quality organic fruits and vegetables?

The ideal dietary approach for anxiety, depression and any health condition is always one that high quality, is personalized and takes into account biochemical individuality. With the removal of gluten, grains and the inclusion of the other dietary changes mentioned above, plus addressing all nutritional imbalances I expect we will see more than one-third of the dietary group experiencing improvements in depression in future trials.  

I truly appreciate the work of Professor Felice Jacka and her team and look forward to seeing more studies like the SMILES trial, using a personalized approach and quality foods that include grass-fed red meat and wild fish, plus pastured eggs or chickens, and healthy fats; and organic produce as a baseline. 

And then future trials that also look at the impacts of these dietary changes on anxiety and depression: gluten and/or grain removal;  removal of high histamine foods and high oxalate foods;  a low FODMAPs diet; the specific carbohydrate diet/SCD; a Paleo diet and so on – all based on biochemical individuality. We know these diets works in clinical practice and now we just need the research to back this up.  In part 2 of the blog, I share some incredibly inspiring diet-depression and diet-anxiety Paleo success stories.

In summary:

• a simple change like switching from junk to real food can have a major impact on your depression and anxiety – ONE THIRD of the dietary intervention group saw improvements in their depression symptoms and many also saw reduced anxiety. This is profound! 
• you may need to make additional dietary changes (gluten-free, grain-free, low FODMAPs i.e. avoiding or adding certain foods based on your biochemical individuality) and always add healthy fats and focus on quality
• you may also need to address brain chemical imbalances with amino acids supplements, address gut health, adrenal issues, low zinc, low vitamin B6, low vitamin D etc. too

Are you encouraged by this research?

And have you made similar dietary changes to those done in the SMILES trial and seen a reduction in your anxiety and depression?

Have you removed gluten or grains and made additional dietary changes, and added supplements and seen even more benefits?

Note: to avoid confusion I’ve used the Australia spelling of “randomised” and “fibre” in the quoted sections and the US spelling “randomized” elsewhere in the blog.