Guest post by Annabel Matison. Annabel is a PhD student at the Centre for Healthy Brain Ageing. Her PhD explores the associations between diet, depression and genetics in older adults.

Promising new research suggests that increasing your fruit & vegetable intake may help reduce your risk of developing depression.

Mental health is finally in the spotlight. Open the paper and you’ll read about the mental health struggles of teenagers and sporting stars, plus of course the impact of the pandemic on the mental health of school-aged children. The figures are grim with 1 in 16 Australians currently experiencing depression, while 1 in 7 will experience depression over their lifetime. What is rarely highlighted, however, is the impact of poor mental health on middle-aged and older adults (a group that I, and many of us belong to). You might be surprised to learn that depression has a larger impact on older adults. Compared to a younger adult, depression in older adults has a greater physical effect, and may lead to a person no-longer being able to live independently. Depression also impacts cognition, with depression in older adults being a leading risk factor for dementia.

Over the last 10 years there has been a growing understanding that what we eat influences our mental health and that by making changes, we may be able to reduce our risk of conditions such as depression. One of the first things that struck me when I started my PhD in this area, is that half of the older adults with depression were first diagnosed after the age of 60. This means if I change my diet now, it could make a meaningful reduction to my risk of developing depression as I age.

What does the research show?

I’ve been working with a cross-functional team to summarise the evidence in this area. We located studies where people without depression aged 45+ had their food intake collected and then they were followed over a number of years to see who would become depressed. We then statistically combined the studies and found that people with higher fruit or vegetable intakes reduced their risk of depression (by 15% for fruit & 9% for vegetables), whereas people who ate what we would consider a Western diet or a diet containing foods which have been shown to be inflammatory increased their risk of depression (by 15% for Western diets & 33% for diets containing inflammatory foods). Based on these results we estimate, that for example, there would be 16 less cases of depression for every 1,000 people who switched from a low fruit to high fruit diet.

Is this research reliable?

People often question me about these studies and ask, “isn’t a person’s diet likely to be influenced by whether or not they have depression?” (i.e. if I’m depressed I feel like eating junk food) and “maybe the benefit is due to the other things that people who eat fruit and veg do, like exercise more?”.

So, there are 3 things I want to point out.

· We only included studies that looked at this relationship over time. The study had to assess diet, and then follow the participant over several years to see if they developed depression,

· “Is the benefit seen due to people who eat more veg having other healthy lifestyle behaviours?” This has been taken into account so essentially the studies use statistical methods to put everyone on an even playing field,

· But yes, none of this is perfect. Unfortunately, it’s difficult to recruit a large group of people, get half of them to eat more veggies for a number of years (if I knew how to do this I would probably win a Nobel prize) and then ask them how they are feeling. There is a good chance that the people who have been “really good” eating all their veggies will tell me they are feeling great compared with the people I told to keep on eating their old diet. I can’t tell if the difference is because eating more vegetables has improved their mental health or if they are just telling me they feel better because that is what they expected eating more veggies would do.

But note…..

A couple of things I want to be clear about, is that we are not saying eating well will solve your mental health issues. We are saying it is likely to reduce your risk of developing depression, but there are other lifestyle factors, like exercise and social interaction which are also important in maintaining good mental health. People should check in with their GP if they feel unwell, not only for their physical health but for their mental health. Also, although our research only looked at people 45+, diet appears to be equally important in younger age groups.

Take home message

The key take-out from our research is to eat more fruit and veg, and less highly processed foods to reduce your risk of depression. The recommendation is to eat those 2 fruit and 5 serves of veggies a day (that we know almost no-one does).

Try shopping around the outside of the supermarket, or even better, visit your local greengrocer as they have a great range of healthy options. There are some easy ways to increase your veggies. Try having vegetable soup with meals (my favourite is pumpkin). In summer I like to have a salad for lunch, and I always serve a side salad with an evening meal. When you do cook those veggies and salads make a bit extra to serve with lunch the next day. It all helps protect your physical and mental health, and the health of your family.

If you need some help getting your healthy eating back on track I can help you wth a private consultation

Annabel is a PhD student at the Centre for Healthy Brain Ageing. Her PhD explores the associations between diet, depression and genetics in older adults. Annabel has a Master of Human Nutrition from Deakin university. Annabel recently published a meta-analysis with her colleagues from UNSW and USyd looking at the longitudinal association between diet and incidence of depression in adults 45+. Annabel is supported through an Australian Government Research Training Program Scholarship.