Like most things in life, our diets have changed over time. Much of what we now eat comes from a factory rather than a farm. And while the impact of that is clear on our physical health – with high rates of obesity, type 2 diabetes and heart disease – less is known about the impact of what we eat on our mental health.
But that is changing.
The Food & Mood Centre, a world-leading research hub in Victoria, is trying to understand how what we eat influences our brain, mood and mental health. Evidence consistently shows that people who eat a healthier diet have a lower risk of depression. And that trend is consistent across the lifespan, from early childhood to older adults, says Dr Hajara Aslam, one of the Centre’s researchers.
When it comes to mental health, there are many parts at play, but it is the role of the gut microbiota that has sparked the interest of the researchers.
What is the gut microbiota? The gut is the home of the gut microbiome which is made up of trillions of microorganisms and their genetic material that live in your intestinal tract. The richer and more diverse these populations of ‘gut bugs’ are, the more benefit they seem to have on your health.
The Food & Mood Centre researchers are particularly interested in how our diets can affect the gut microbiota, and how that in turn influences our mental health. Previous research has shown that the gut microbiota changes in response to what we eat. And it can change fast.
Dr Samantha Dawson, a research fellow at the Centre, says several studies have looked at the impact of different diets. A diet rich in meat, cheese and eggs versus a plant-based diet had surprising results. “Within that first 24-hour period of starting a different diet, they could detect a change in the gut microbiota,” she says.
This discovery was heartening to the researchers because it suggests that changing your diet can rapidly change your gut bugs, and this may influence mental health. So how does your gut microbiota affect the brain, you might ask?
Research has shown that the gut microbiota changes in response to what we eat."
The relationship between your gut microbiota and your brain is complex. It is also bi-directional, which means the organs ‘talk’ to each other.
The gut microbiota is involved in pathways that produce serotonin and dopamine – the brain chemicals that are linked to mood, motivation and feelings of reward.
What’s more, Dr Dawson says, the gut microbiota of people with depression looks different to that of those without depression. “We recently reviewed over 40 studies comparing the gut microbiota of people with mental health conditions (such as depression) to people without mental health conditions, and we saw consistent differences between the two groups.”
There is still a lot to discover. But even so, the overall evidence suggests that a healthier diet is linked to better mental health and a healthier gut microbiota.
The gut microbiota of people with depression looks different to those without depression."
To support your gut health and mental wellbeing through your diet, it’s best to focus on wholegrains, vegetables, fruits, legumes, nuts, lean protein and healthy fats. Good gut bacteria also thrive on fibre.
Jean Hailes naturopath Sandra Villella recommends the Mediterranean diet, as it is rich in plant foods and healthy fats from olive oil, fish, nuts (especially walnuts) and seeds. She says these foods fight inflammation through their antioxidant action, and this in turn may protect brain and nerve cells from damage.
Wholegrains like brown rice, oats and barley also form part of a brain-healthy diet, as they are rich sources of B vitamins “which play important roles in the making of neurotransmitters (brain chemicals) that affect mood”, explains Ms Villella.
Other cuisines also follow similar principles by being rich in whole foods, however the Mediterranean diet has a large amount of published scientific research behind it for promoting health and longevity.
Learn more about the Mediterranean diet.
To embark on a new diet pattern, it’s best to start simple and small. “If you’re someone who doesn’t eat vegetables at all, start by including one serve a day, then gradually increase it,” says Dr Aslam. Aim for variety in your choice of vegies, and consider adding spices like cumin and turmeric to your cooking – both have anti-inflammatory and antioxidant properties.
The good news is, eating to support your mental health is within everyone’s reach. “It’s about what you do most of the time,” says Dr Dawson. “If you’re following a healthy diet pattern with good habits for most of the time, that is a good way forward.”