May 1, 2019
The idea that certain foods can make us happy is instantly familiar.
For some it’s the comfort of our favourite junk food. For others it’s the sugar hit of ice cream or chocolate. What could be better than cheering ourselves up with a favourite treat?
By now you’re thinking the obvious,- don’t we pay a high price for a fast sugar hit? Doesn’t our mood spike, then plummet again? Aren’t we left with an inner voice telling us we’re a big fat pig? Surely eating to feel good is an obvious trap, right?
Not so fast. Recent research is changing the way we think about food and mental health.
Welcome to your microbiome.
For many years the digestive system was considered one of the simplest systems in the human body. After all, what’s complicated about a long tube for digesting food and excreting waste?
However, recent advances in DNA technology have discovered the gut is far more important. Deep in your gut, billions of microorganisms are working to keep you healthy. This includes ‘good’ bacteria helping digestion, supporting your immune system, promoting physical health, and producing key nutrients that we can’t produce ourselves. But it also includes ‘bad’ bacteria linked to poor immunity, endocrine disorders, weight gain, autoimmune diseases, and cancer. Moreover, gut health has now been directly liked to mental health.
Everything you eat and drink is feeding either the good bacteria or the bad bacteria. The bad bacteria thrive on the sugar and unhealthy fats that are everywhere in our modern diets. They especially love junk food. And, as they multiply, they demand more and more – something we experience as cravings. This is why a poor diet actually increases cravings for more of the wrong foods.
In contrast, diets such as the Mediterranean diet, which is high in plant-based foods (fruits and vegetables), whole grains, legumes, fish, good fats (e.g. olive oil, avocado) and small amounts of red meat promote good bacteria and are linked to better physical and mental health.
Can better food strengthen mental health?
The world’s leading research into food and mental health has been conducted by Professor Felice Jacka; head of the Food and Mood Centre at Deakin University, and president of the International Society for Nutritional Psychiatry.
Researchers have known for some time that a healthy diet is associated with positive mood. However, Professor Jacka has conducted the first ever clinical trials to see if switching diets can improve the mental health of people experiencing depression.
The ‘Smiles study’ (Supporting Modification of lifestyle in Lowered Emotional States) recruited 67 people experiencing depression, and randomly allocated them into two groups. One group attended seven sessions with a dietitian who placed them on the Mediterranean diet. The control group received friendly conversation sessions with no dietary advice. After 12 weeks, those on the Mediterranean diet were significantly less depressed compared to the control group.
Professor Felice Jacka
More recently these findings were replicated in a study at the University of South Australia;- the HELFIMED study. This study allocated 150 depressed participants to either Mediterranean diet cooking classes, or a control who participated in social activities with no dietary advice. As expected, both groups improved their symptoms, as social connectedness is already known to support mental health. However, the Mediterranean cooking class group showed significantly more improvement. Also, those participants who made the biggest improvements in their diets achieved the biggest improvements in their mental health.
These studies monitored the affordability of the changes in the participants’ diets. The participants in the SMILES study spent $26 less per week on food and drink than previously.
In both studies the improvements were dose sensitive. This means participants who only made small improvements in their diets still had some small benefits. While those who made biggest improvements enjoyed the biggest benefits. So no excuses! Instead of thinking ‘it’s all too hard’ remember even small changes to your diet will produces at least some improvement in your physical and mental wellbeing.
Putting it all together
1. Starve the bad ones.
The more you feed a stray cat, the more it hangs around. Bad bacteria thrive of junk food and processed food. If you cut down the supply of sugars and fats you will reduce their numbers, thus reducing the cravings they produce.
2. Feed the good ones.
Increase good bacteria by eating more whole plant foods such as fruits, vegetables, legumes, and whole grains. Investigate the Mediterranean diet.
3. Think diversity.
Diversity does not mean a large bucket of carrots. Include small amounts of many different plant-based foods. A healthy microbiome is like a tropical rainforest. The healthier the environment, the more diversity of species. Diversity supports wellbeing and prevents bad bacteria from dominating. Like a noisy group of children playing together, the bigger the group the harder it is for noisy individuals to dominate all the attention.
References and further reading
1. Michael Mosley. The Clever Guts Diet. (2018). Simon & Schuster
2. Felice Jacka. Brain Changer; Good Mental Health Diet. (2019). Booktopia.
3. Jacka, F.N., O’Neil. A. et.al. (2017). A randomized controlled trial of dietary improvement for adults with major depression l) BMC Medicine. 15:23
4. Lassale. C., Batty, G.D. et.al. (2018) Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis. Mol Psychiatry. Sep 26. positive psychology