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Food and Mood - The Link Between What We Eat And How We Feel

6 min read
15/01/20 11:41

You Are What You Eat

The saying “You are what you eat” seems to have its origins almost two centuries ago. The French lawyer, politician, epicure and gastronome Jean Anselme Brillat-Savarin (probably a 19th century version of someone like celebrity chef and molecular gastronomist Heston Blumenthal), wrote in his 1826 book “Physiologie du Gout, ou Meditations de Gastronomie Transcendante the words “Dis-moi ce que tu manges, je te dirai ce que tu es” (tell me what you eat and I will tell you what you are”.


The phrase made its first appearance in English about 100 years ago in the Bridgeport Telegraph newspaper under an advertisement for beef, with the tagline: “Ninety per cent of the diseases known to man are caused by cheap foodstuffs. You are what you eat.” Even 100 years ago, we seemed to understand the direct link between nutrition and health. About 20 years later, the American radio presenter and writer Victor Lindlahr wrote a book entitled “You are what you eat: how to win and keep health with diet”.


What about mental health?



In essence, we’ve known for a long time that what we eat contributes to our health but we’ve tended to remain focused mostly on physical health. What about mental health? It’s not hard to theorise that nutrition and diet would contribute to mental health indirectly. For example, a diet high in processed foods, with high amounts of added salt, fat and sugar and low amounts of dietary fibre and low levels of phytonutrients will almost certainly lead to medium term physical health impacts (like reduced stamina, feelings of sluggishness and in the longer term, a likely increase in non-lean body mass, reduced participation in activity and exercise and increased disease risk. This will almost certainly impact mental health at some level – it’s hard to imagine being at the top of your mental game if your physical wellbeing is below par.


But could food impact mood and mental health more directly than that? As it turns out, the answer seems likely to be “Yes”. There’s a great deal of research currently in the area of food and mood and one of the leading researchers is Australia’s own Professor Felice Jacka, from the Food and Mood Centre at Deakin University. As a whole, this field of research is called “Nutritional Psychiatry”.


The SMILES trial


In 2017, Prof Jacka and her team published the results of a randomised control trial which looked at whether a modified diet could improve symptoms of depression. Named the SMILES (Supporting the Modification of lifestyle In Lowered Emotional States) Trial, their conclusion noted “the results of our study suggest that dietary improvement guided by a clinical dietician may provide an efficacious treatment strategy for the management of this highly prevalent mental disorder”. This is exciting for a number of reasons.


Firstly, if diet can “treat” or “reduce/eliminate signs and symptoms and reverse disease”, then the next question to consider is “could diet prevent the onset of depression?”. As far as I know, there are no published studies currently which answer that question but it’s certainly worth asking, but there are already studies showing that poor diet is a risk factor for poor mental health.


Secondly, given what we know about the side effects of pharmacological treatment for depression (which can include nausea, vomiting, diarrhoea, headache, drowsiness, dry mouth, insomnia, nervousness, agitation, restlessness, dizziness and sexual problems), what’s not to love about a potential treatment that doesn’t have those??


It’s true that depression is a complex disease and that the same treatment can work very effectively for one person and not very well at all for the next; however, all avenues of treatment should be available and the “lifestyle intervention” avenues make sense to include since their cost is almost nothing and their unpleasant side effects are non-existent. So what did the people in the treatment group of the SMILES Trial actually eat?


In essence it was a modified version of the Mediterranean Diet which looked like this:


· 5-8 servings of wholegrains per day

· 6 vegetables per day

· 3 fruit per day

· 1 serve of raw and unsalted nuts per day

· 2-3 serves of low-fat unsweetened dairy foods

· 3-4 serves of legumes per week

· At least 2 serves of fish per week

· 3-4 serves of lean red meat per week

· 2-3 serves of chicken per week

· Up to 6 eggs per week

· 3 tablespoons of olive oil per day


Extras: no more than three servings per week of sweets, refined cereal, fried food, fast food and soft drink

Alcohol: no more than two glasses of red wine a day, only with dinner (other alcohol was included as an 'extra' food)

The Gut Microbiome


Most people are familiar with the name of the neurotransmitter Serotonin, which is responsible for several functions including regulation of sleep and appetite, mood mediation and pain attenuation. What most people don’t know is that 95% of your serotonin is made not in your brain but in your gastrointestinal tract – your gut! So your digestive system is not just important for the processing of food – it turns out it plays a central role in functions we once thought of as solely occurring in the brain. The gut is lined with literally billions of neurons and their health and capacity to do their job as well as the production of serotonin are influenced by gut health. So what makes for good gut health? In short, a wide variety of micro-organisms, bacteria, viruses and fungi make up the Gut Microbiome and it is this variety that appears so central to good gut health and ultimately good brain health. The strength and variety of the microbiome is influenced by a number of factors including how we were fed as infants, where we live, how we manage stress and everything we put in our mouths – whether it’s food, drink or pharmaceuticals. Other neurotransmitters which have a major gut involvement include Dopamine – central to motivation and reward seeking behaviour and GABA (Gamma Amino-Butyric Acid) which is central to restful sleep, feeling calm, and moderation of anxiety and stress. So when we think about food and diet and their impact on mood, the link is very strong and very direct!

A recent study found that 61% of surveyed internal medicine residents had little or no nutritional training as part of their studies. Thankfully this is beginning to change and we are starting to see nutrition education built into medical studies.


The Take Away (pun intended)


First of all, if you have any concerns about your underlying mental health, contact your GP, or EAP, straight away. About half of our population will experience a mental health issue at some stage in their lives - so if this is you, you’re not alone and there’s really nothing unusual about experiencing poorer than usual mental health any more than it’s unusual for us to become physically unwell from time to time. Early intervention in mental health issues almost always leads to faster, greater and longer lasting outcomes. Talk to your GP about the available treatment options which include lifestyle modification (including diet, exercise, sleep, social interaction, stress management and substance avoidance), psychological treatments and pharmaceutical treatments.


Even if you don’t have significant concerns about your mental health, but you feel like you’re not “thriving” as much as you’d like, have a close look at your diet and consider what modifications you may be able to make, bearing in mind the outcomes of the SMILES Trial.


Secondly, if you’re managing any underlying health condition, or if you’re not sure how to go about eating better quality food, talk to your GP again and ask about a referral to a dietitian. There’s a lot of public interest in food, diet and nutrition and some people think there’s a lot of contradictory information about food and what we should be eating for optimal health.


I happen to think in many ways it’s actually not that complex…our physical and mental health has a number of contributing factors - diet, exercise, sleep, social interaction, stress management and substance avoidance. We need to make sure we’re managing all of these well. There’s an old saying in the fitness industry – “you can’t outrun a bad diet”, meaning exercise won’t do much if your diet is really poor. The same thing is true of all these factors though – you can’t out-eat chronically poor sleep and low levels of activity – at some point your physical and likely mental health will suffer. So food is important and all the other elements are important too! And they all interact with each other.


For the simplicity of the message and its capacity to cut through all the “noise” about diet and food, I like the words of the American academic and author Michael Pollan who wrote in the New York Times several years ago: Eat food, mostly plants, not too much.



Simon Matthews


Writing exclusively for MindRazr, Simon is the CEO of Wellcoaches® Australia, an AHPRA Registered Psychologist, Board Certified Lifestyle Medicine Professional, Fellow of the Australasian Society of Lifestyle Medicine. He's also a Fitness Trainer and Nutritionist.


Food & Mood


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