The body is an interconnected organism: we know the quality of our diets can affect its ability to function, both positively and negatively.
And according to research, the food we consume has an impact on our brains, and consequently our mental health.
According to Beyond Blue, one in seven Australians will experience depression during their lifetime, and a quarter of the population will experience anxiety.
If mental illness is inevitable for much of the population, we need to find other ways to treat and prevent it.
And our diets are sure to play an important part.
Keeping the hippocampus happy
Our diets affect all areas of the brain. But when it comes to mental health, we’re particularly concerned with the hippocampus, a centre for emotion and memory in the brain.
Professor Felice Jacka, Director of Deakin University’s Food & Mood Centre, says there’s been extensive research – in animals and humans alike – to show the size and function of the hippocampus changes thanks to our meals.
It ultimately comes down to the nutritional value of what we eat.
“Healthy dietary components – such as polyphenols, which are found in plant foods, and omega 3 fatty acids – are seen to promote the growth and function of the hippocampus. Foods high in fat or sugar tend to impair it.”
These components also affect our immune systems, which in turn are connected to our mental and physical health.
One of the driving forces behind our immune systems is a little thing known as the gut microbiota: a mysterious grouping of bacteria that we’re still learning to understand.
Coincidentally, it also affects the size and function of the hippocampus, as well as other elements of human physiology that affect mental health, such as the immune system and metabolism.
Although we don’t know everything about the gut microbiota yet, we do know that having a diversity in gut bacteria is consistently linked to better health.
“And we’re pretty sure we know how to get that: the more diverse plant foods you take in, the more diverse the microbiome will be.
“People who are having 30 different types of plant foods per week will have a more diverse microbiome than those who are having 10 or fewer different types of plant foods per week.”
If you’re looking to increase your plant diversity, Mediterranean-style meals are a good starting point.
You can also follow the Australian Dietary Guidelines, a definitive guide to healthy eating.
Nutrition as treatment
Speaking of the Mediterranean-style diet, researchers at the Food & Mood Centre tested its impact on mental health in 2017, through the SMILEs Trial.
It emphasised plant foods over more Western-style food products, which typically come in packets and contain added salt, fat and sugar.
The trial found that switching to a healthier diet can cause a substantial positive impact on clinical depression.
Although further trials are needed, the research suggests that nutrition should be factored into mental health treatments.
Currently, people with elevated depressive symptoms can access antidepressant medications through their GP. They can also speak with a clinical psychologist for 10 free sessions.
Perhaps in the future we’ll see 10 free sessions with a dietitian also on offer?
Healthy eating affects everybody
It sounds deceptively simple: eat a healthy, balanced diet with lots of plant foods, and you could really be giving your mental health a helping hand.
But very few Australians actually adhere to the guidelines. Less than five percent of adults, and under one percent of children get their recommended intake of fibre-rich foods like vegetables and legumes.
“It’s not just something that affects people who have limited income or limited education,” Professor Jacka says.
“This is something that affects everybody.”
Poor diet is now the leading cause of chronic illness and early death around the world, thanks to its links to health conditions like obesity, diabetes and cardiovascular disease – all of which are exacerbated by mental illness.
“We need people to understand that our diet doesn’t just affect our physical health. It affects our brain and mental health from the start of life.”
Professor Jacka is the Director of the Food and Mood Centre at Deakin University, and the founder and president of the International Society for Nutritional Psychiatry Research (ISNPR).
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