[MUSIC] Thank you very much for your time today Felice. Can you tell us a bit about how our modern lifestyle and forms of food consumption are actually effecting the health of the population. >> Sure, well look, over recent decades there's been really profound changes to the food system due to globalization. And this has really changed the way that people eat right around the globe. So what we find now is instead of traditional dietary patterns in different countries, people are more increasingly eating foods that are highly processed. They're high in added sugars and added fats. All sorts of things that we know is not good for our health. Now, the impact of this has given rise to the very well-publicized obesity epidemic. But it's also given rise to really a tidal wave of chronic illness, such as heart disease and diabetes. And in fact, unhealthy diet is now the leading risk factor for early death. So its outstripped infectious diseases such as HIV, malaria, etc., to be the leading killer globally. >> What does the research say about the relationships between diet, depression and anxiety? >> Well over the last six year or so, there's been an enormous amount of research done right across the world. Looking at the relationship between the quality of people's diets and their risk or likelihood of having, what we call, the common mental disorders, depression and anxiety. And what we have seen across countries, across cultures, across age groups consistently is that people who eat the healthier diet. More of the vegetables and fiber-rich foods that we know are so important. It reduced risks for these disorders. Whereas, those who eat more of the the unhealthy and processed foods are more at risk. Now importantly, these relationships are independent of a whole range of other factors that could explain the relationships. So things such as peoples' socioeconomic status, their education, their weight, their physical activity, etc. And they're also not explained by reverse causality. Because, of course, some of these mental disorders are associated with dietary or appetite changes. But these relationships seem to be quite independent of that, particularly over the longterm. And the important thing to note is that this is true right across the life course. >> Can you tell us a bit about how this is affecting children perhaps even more than everyone else. >> Well, what we know is that the changes to our global food system and the dietary habits of people has been particularly obvious in younger people. So even in Australia, the latest national nutrition survey tells us that only about half a percent of children are actually having the required intake of vegetables per day. So, of course, this has a profound impact on their health going forward. And we've known for a while now, with the research that we and others have done. Is that the quality of children and adolescents' diets is linked to whether or not they have depression, in particular, or psychological distress. And this, again, seems to be independent of things such as their family’s socioeconomic background. Family conflict, poor family management, those sorts of things. And indeed, this is the case even at the very start of life. So we've shown that the quality of mothers' diets during their pregnancy is linked to their children's mental health as they get older. And others have also shown that this is true for their risk for autism spectrum disorders and cognitive development. And now, this is really important, because half of all mental disorders start before the age of 14. So if we want to think about modifiable risk factors and prevention, diet seems that it may be a very good target. >> How much do we know about how our diet actually affects our brain functioning? >> Well, there's been a lot of research in animal studies, of course, which makes it easier to study this particular question. And we say that nutrition has an impact on the brain, a very widespread impact. So unhealthy foods fed to pregnant animals results in many changes in the brain of their offspring, for a start. Such as their neurotransmitter gene expression, the reward system, stress response system, etc. But really key is that unhealthy foods seem to have an impact on brain plasticity. And indeed, last year we published the first study in humans. To show that the quality of peoples' diets, these were older adults, was related to the size of their hippocampus. And the hippocampus is a key area of the brain that's central to learning and memory but also to psychiatric disorders. And people who had a healthier diet tended to have a larger left hippocampus. And those who had unhealthier diets had a smaller left hippocampus. And this wasn’t just a small effect, this was quite a large effect. So this really has implications for brain health, not just at the end of life, but right across the lifespan. Can you tell us about your new study, using diet to treat depression? >> Yes, so this is really exciting. Because of course, over the last six years or so, most of the work that's being done in the new area of nutritional psychiatry has been observational studies. So where you collect data from large samples of people and you use statistics to test associations. Or they've come from animal studies. But, of course, there's problems with all of those sorts of studies, and we really needed to test the causal hypothesis. Meaning that we needed to do a trial to see whether if we took people with major depression, people who are already depressed. And we help them to improve their diet by increasing their intake of nutrient dense foods and fiber and vegetables. Fruits, whole grains, fish, olive oil, those sorts of things. And also decreased the intake of the other processed and unhealthy foods, whether or not that would actually help their depression. And indeed, we were really stunned to see that it certainly did help, and it really helped. There was a very large effect size. So what this tells us is that if we have patients with depression or people in the community with depression. By improving their diet, they very well may be able to help to improve their depressive symptoms. And of course, this has real implications to clinical practice as well. Because improving diet will also have a positive benefit for the physical health problems that often go with depression. >> So it sounds as though we need interventions at the individual level, but also at the community level. >> That's correct. So this whole new body of research and this field of nutritional psychiatry really has implications for population health and also clinical practice. So at the population level, it's really essential that we address the obesogenic environment. And that really means addressing the activities of the food industry around marketing. And maybe using things such as taxation, limiting availability, etc., to change the food environment from one where unhealthy foods are the default. To one where healthy foods become the easiest option, the cheapest, the most socially acceptable. [MUSIC]
