Do you feel guilty when you regularly have slumps? And the injunctions of the ‘come on, shake it off!’ type don't work and only aggravate your feelings of powerlessness or guilt? The good news is that science is making giant strides in this area and it is now clearly established that depression is not just a matter of willpower, it is also very much a question of nutrition.
- With Anne Weber
Nutritional psychiatry
It's only in the last fifteen years or so that researchers have become aware of the impact of what we eat on our brain and how it plays a central role in depression and, more generally, on our mood.
These scientific developments are at the frontier between nutrition and psychiatry, and scientific papers on the subject are appearing almost daily.
Scientists consider this to be a new discipline in its own right: nutritional psychiatry, which can be defined as the discipline that studies how nutrients affect our moods and behaviour.
It concerns mood, but also our tolerance to stress, inflammation, vitality, sleep, cognition and dysfunctional behaviour. This new discipline brings together epidemiologists, nutrition researchers and psychiatrists.
SMILE
I became interested in the subject in 2017/2018 after discovering the SMILE trial of the " Food and mood Center " from Deakin University in Melbourne, Australia.
I was taken aback by its incredible results.
The subjects of this serious scientific study were all suffering from depression (moderate to severe). After 3 months on a diet free from ultra-processed foods and including large quantities of plants, 30% experienced complete clinical remission of their depressive syndromes.
In other words, 30% of genuinely depressed patients were cured within 3 months by a simple change of diet.
The Mediterranean diet, but not only
Which foods are best? The SMILE trial, followed by many others, studied the Mediterranean diet.
To sum up its composition: every day (exercise, water, fruit, vegetables, wholegrain cereals, spices and nuts) , every week (fish, eggs, white meat, pulses and dairy products made from goat's or sheep's milk), and occasionally (sweet treats and red meat).
But it's important to point out that all traditional diets, all over the world, obtain similar results in the various studies when they don't contain ultra-processed foods and include large quantities of plants. They are also associated with better mental health, and reduce the risk of developing depression by 30 to 35%.
Ultra-processed food
In the studies involving ultra-processed foods (UPFs), the scientists did the opposite of the SMILE trial: they selected adults with no symptoms of depression and increased the doses of ultra-processed foods.
The results of three meta-analyses are indisputable: an increase in ultra-processed products in the diet goes directly hand in hand with an increase in the risk of reporting depressive symptoms.(1).
A chicken and egg situation ?
The doubters will say ‘it's a well-known fact that when you're depressed you eat badly, and not the other way round!'
Professor Felice Jacka, a pioneer and authority in the field of nutritional psychiatry, took care to verify in several studies that it was not depression that led to a poorer diet.
Bipolar disorder and the ketogenic diet
The area of research and application is constantly expanding.
Recent promising results show the effects of the ketogenic diet (high in fat and low in carbohydrates) on bipolar disorder. (1).
Foods are studied one after the other, and the studies follow one another at a very steady pace.
One thing is certain: what we put on our plates every day has a major impact on our mood.
In short: good food AND very little ultra-processed food.
According to Felice Jacka, there are two parameters that make up a ‘good diet’ from the point of view of mental health and mood: eating enough good food (plants, vegetables, fruit, cereals, pulses, nuts and seeds) AND eating a diet that includes a small amount of ultra-processed foods (UPT).
You need to combine the two: healthy food at home is not enough if you eat junk food outside the home, whether you're a teenager going to a chain store with a clown as its mascot, or an adult on a business trip eating ready meals in a hurry.
If reading this article has inspired you and you want to get started today, it may be easier than you think. You could, for example, start by changing your habits at work and learning about the reality of ultra-processed foods to make them less desirable.
The end of the 2 p.m. rush
In 2018, after measuring the impact of food on mood, we systematically carried out a short study with all the teams we worked with on the food and drink available in the workplace. Surprisingly, the vast majority of participants actually wanted something other than the sugary drinks and pastries or cakes that abounded during breaks.
They just hadn't thought about it as a group. Fresh water, good coffee, a nice choice of tea and fruit made the majority happy, at no extra cost, and with a reduction in the 2pm energy crash. Some teams with top sportsmen and women added oilseeds and dark chocolate.
You could start simply by discussing as a team the content of your coffee breaks and other social moments and see what you really want collectively. It's often easier to introduce and maintain new habits as a group.
Find your ‘immortal fries'
When it comes to our bad habits, whether in food or in name, it is always useful to provoke a ‘disenchantment’. In fact, when the brain realises that the habit it has ingrained for your own good is not in fact the right choice, it is capable of reprogramming itself.(3).
Personally, ‘immortal chips’ have played a large part in my disgust with fast food chains, for example.
In the science centre that I ran in the early 2000s, we hosted the exhibition ’ Creepy Crawly ' of the Danish centre Experimentarium. Nous avions traduit le titre de l’exposition par ” Les petites bêtes qui vivent avec nous et sur nous “.
One of the displays that struck visitors was a large transparent cabinet with one side refrigerated and the other not. Identical foodstuffs were placed on either side and photos were taken automatically at regular intervals, transformed into short films to give an accelerated view of the putrefaction process.
This made it possible to see the differences in putrefaction rates between foods, and also between those in the fridge and those at room temperature.
That's where I discovered these ‘immortal fries’.
We put a portion of fries from a famous fast-food chain into this two-compartment cupboard .... and found that they didn't rot. Retaining their original appearance for days, weeks .... months... Hence their nickname of ‘immortal fries’.
A better understanding of what we eat can create the conditions for disenchantment and help us to break our eating habits if we so wish.
You too can try the immortal fries experiment or just watch the 2004 documentary ‘ Supersize me " who gave us the idea for this test. If you haven't seen it, it's a documentary you can watch with the whole family. It's as entertaining as it is informative.
(1) https://foodandmoodcentre.com.au
(2) Read the article La recette du bonheur " by Hélöise Rambert in the magazine Epsiloon from October 2024
(3) See Justin Brewer's research, some of which is reproduced in French in his book ‘Craving, comment on devient accro et comment s'en libérer’. https://arenes.fr/livre/lecraving/