We’ve all felt the effects of food on our mood, so it would stand to reason that dietary intervention for mental health would be well-studied and a regularly deployed treatment.
But this is far from reality, as historically, psychiatry was only concerned with what happened from the neck up.
Felice was the driving force behind the landmark study to determine if dietary intervention could help treat the symptoms of moderate to severe depression.
With her help, we dive into what the science suggests regarding the relationship between food and our mental health and what foods we can eat to improve it.
If you want to uncover the right foods for your body, head to joinzoe.com/podcast and get 10% off your personalized nutrition program.
[00:00:00] Jonathan Wolf: Welcome to ZOE science and nutrition, where world-leading scientists, explain how their research can improve your health.
Can food really determine how we feel? Okay, we might feel a bit cross if we are hungry, but surely major mental health problems like depression and anxiety can't be caused by what we eat. Well, it turns out they can. If you are feeling a little anxious or low in mood right now, it could be that breakfast cereal you have each morning.
Today, I'm delighted to be joined by Felice Jacka, a professor and international leader in the new field of nutritional psychiatry, who has turned our understanding of mental health upside down. Her clinical studies for the first time measured how changing what we eat can affect how we feel.
In one groundbreaking study, a third of participants with severe depression went into complete remission as a result of changing their diet. In this episode, Felice helps us understand what the latest science tells us about the relationship between food and our mental health, and then gives us practical advice on what foods we can eat to improve it.
Of course, not all low mood is caused by food. And if this episode triggers any concerns, there are links in the show notes to groups that can support mental health issues.
Felice. Thank you for joining me today. Very exciting to have a guest in from Australia. Why don't we start with a quick-fire round of questions from our listeners?
[00:01:33] Felice Jacka: Sure.
[00:01:35] Jonathan Wolf: Brilliant. Can we improve our mental health by changing what we eat?
[00:01:40] Felice Jacka: Yes.
[00:01:41] Jonathan Wolf: Can diet make us more or less anxious?
[00:01:47] Felice Jacka: Probably.
[00:01:49] Jonathan Wolf: Can our gut bacteria affect our mood?
[00:01:53] Felice Jacka: We think so.
[00:01:54] Jonathan Wolf: And finally, if I change my diet, will it take a long time to notice changes in my mood?
[00:01:53] Felice Jacka: No.
[00:01:54] Jonathan Wolf: Brilliant. Well, I think we're gonna get into all of that in the next little while. And why don't we just start at the beginning. Just very briefly explain when we talk about mood, what does that actually mean?
[00:02:13] Felice Jacka: So we usually talk about depression and, depression is one of what we call the common mental disorders. Depression, and anxiety, they often go together, and they are very common, unsurprisingly. And in fact, when you look at the burden of illness, which it's how much it affects people and affects their ability to participate in their lives and employment and education and all of these things, across the world, those common mental disorders account for a huge burden of disability.
Most of the evidence to date from the field of nutritional psychiatry research has focused on depression and to a lesser extent, anxiety, thus far, but we are now starting to move into other different sorts of mental disorders as well. So when we talk about mood, we're mainly talking about depression.
[00:03:02] Jonathan Wolf: Got it. And so when we talk about mental health and the mental health burden, which is something we talked a lot about, right, during COVID and afterwards. Is that mainly sort of for you as a scientist depression, and anxiety or is that then a much broader set of things?
[00:03:18] Felice Jacka: Look, it's depression and anxiety, but psychological distress. So, you know, when you talk about clinical depression, you're talking about a particular set of symptoms that fulfill a particular set of criteria, but you know, the psychological distress affects everyone at different stages and it's distributed in the community and it seemed to go up quite a bit during COVID for obvious reasons. So, it encompasses all of that.
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[00:03:42] Jonathan Wolf: This feels like a topic that we're starting to talk a lot more about now. And then when I think about when I was a child, we hardly talked about it all. And I see the difference with my own children and how much the school focuses on this. And we worry about it. I guess, is that true? And why is it that somehow all of us, including, I think, you know, doctors and researchers seem to be much more focused on mood today, than in the past.
[00:04:06] Felice Jacka: I think psychiatry was always set a little bit apart from the rest of medicine. It had a stigma around it. There were lots of cultural, sometimes religious reasons why people thought that if someone had a mental disorder that there was something that was profoundly wrong with them in a way that was shameful. And that stigma still persists and people will still be very guarded about admitting that they're taking medications for a mental disorder or that they are periodically unwell with a mental disorder, which is not true if you were talking about another sort of chronic illness. And so a lot of work and effort has gone into trying to break down those barriers and the stigma and to make the discussion far more open.
And I think again, COVID has really allowed that conversation to be expanded because everybody was suffering. You know, we were always a planet going through this one big thing together. So, there's a lot that we don't know in psychiatry, and I think the brain is just so complex. I mean, I always say that we probably know more about the wider universe than we know about the human body, and particularly the human brain. It's just so complicated, and there are so many things that we just can't even explain.
[00:05:13] Jonathan Wolf: On top of that, I think particularly about maybe my grandparents' generation, but my parents' generation maybe also as well that I think treating this idea that your brain is completely separate really from your body. So, you know, you should just, I'm English - ‘stiff upper lip’, right. You should just get on with it and you know, anything that's happening physically to you shouldn't really have any impact on your mind. So, like this real separation. How do we think about that today?
[00:05:36] Felice Jacka: Well that's very true. And actually, really, that's only just been challenged in the last 20 or so years, I think. Certainly, traditionally psychiatry only concerned itself with what happened from the neck up. And to my mind and I mean, I came to this field quite late. It was my second career, but when I came into it, it was around the time that this new field was developing.
Now it's called psycho neuro immunology, which is a real mouthful, but it's basically understanding how our immune systems and this pernicious little thing called inflammation that I think we've all heard about now, can affect our mental health and how our mental health can affect our immune system. And this was pointing to the fact that hang on, this is not just something that's happening in our brain, this is something that's actually happening in the rest of our body. And gee, what do you know? Maybe we are one highly integrated, highly complex system, and that it's not just all about neurons and neurotransmitters that happen in our heads.
[00:06:34] Jonathan Wolf: I think when you think back on it, it's completely crazy to think about this as separate, right? Like we all know that if you have a really bad night's sleep, everything that goes on with you, your effectiveness, your mood, all these things. It's completely changed. You know, it's so obvious that this system is interlinked. It's rather remarkable that we were so resistant to studying this until so recently.
[00:06:54] Felice Jacka: You'd be amazed at how many people in psychiatry still think this way. Like, it's still considered to be quite revolutionary. So…
[00:07:01] Jonathan Wolf: Well, let's talk about it because I think you have done some of these, really seminal studies, really providing the science to understand these links and particularly to do with food. So, maybe just start by telling us maybe, I mean the SMILE study is one that's obviously very famous. I know you've done a series of follow on studies. Maybe tell us a bit about what the results were and why you did this and what it tells us.
[00:07:25] Felice Jacka: I probably go back further than that, if, if that's okay. Because how I got into this was quite interesting, and as I said, I came into it as my second career and it was quite unexpected and through a very circuitous route. But when I came into psychiatry research, I was intrigued to realize that unlike the rest of medicine, there really wasn't much literature around the way, what we eat might affect our mental health. And as I said around this time, there was this increasing understanding that our immune system was important in our mental and brain health. And of course, diet is a really important thing that affects our immune system. Also, around the time there was increasing knowledge coming out of America about this new region of the brain, the hippocampus, which is the one region of the brain that puts on new neurons throughout life. It's what we call plastic. It grows and shrinks, and that diet really could affect this region of the brain that we also know is important in mental health, as well as learning and memory.
So there seemed really good reasons to look at this, but it just hadn't really been looked at before. So I set out to do this for my Ph.D. and everyone thought I was a bit bananas, and you know, like, certainly from the point of view of psychiatry, it was something that people hadn't thought about or if they did, it was with a great deal of skepticism because there'd been some terrible misinformation promulgated by this field of orthomolecular medicine without any evidence, and so it was really tarnished. And I had to just kind of make it up as I went along and take all of the methods from nutrition science and try and apply them in psychiatry. But long story short, my PhD looked at the link between the quality of women's diets in this large population cohort, and the presence of clinical depressive or anxiety disorders.
And of course, taking into account all those things we really have to consider, like people's income and education, and as I said, body weight and other health behaviors and things like that, and showed that there were these connections. Now, that was considered so kind of revolutionary that it ended up on the front cover of the American Journal of Psychiatry. That was in 2010.
And Medscape Psychiatry nominated it the most important study in psychiatry for the year and the whole thing. Now, I think that's kind of cute when I look back on it that a cross-sectional observational study could have this sort of impact, but it was really because it just hadn't been looked at before.
And then at almost like within a three month period, there were another two really key studies published in the other two leading journals in psychiatry research that didn't look at clinical depression. They looked at depressive symptoms, but they were prospective studies. So they looked at the quality of people's diets and their risk for developing depression over time.
And they're both again, showing the same thing, that the quality of people's diets really predicted the risk for developing depression. Again, independent of all those other things. So these all coming together in the three leading psychiatry journals within a very short period of time really kind of set the field on fire and everyone suddenly went, oh my goodness.
So I was able to go and do a lot of research in this area, using what we call epidemiological data. That's not an experiment, it's just we collect data and we use statistics to put them together. And over that time then, ensuring probably the following 10 years, it developed a very large, very comprehensive, and very consistent evidence base to tell us that the quality of people's diets was related to their risk for depression.
And indeed, if people have a healthier diet quality, their risk of developing depression seemed to be reduced by about 30%. Now, this is across countries across cultures and across age groups and right from the start of life, right up to the other end. And so it was when we got to this point, obviously. We also know that correlation doesn't equal causation.
So while you've got a very comprehensive and consistent body of evidence backed up by all these animal data and experiments, we needed to do an actual experiment to say, okay, if we take someone who has clinical depression and we help them to improve their diet, does that improve their depression? And that's what we did with the SMILEs Trial.
[00:11:45] Jonathan Wolf: Which is quite a radical idea, right? It's basically saying you've got, you know, a serious condition here and we are going to prescribe food. You know, that is sort of the definition of food as medicine, isn't it? So that's very exciting and rather radical. Was it hard to convince people to do this? Or at this point had all this weight of evidence got them to the point that they were like, of course, we should go and feed them some plants.
[00:12:09] Felice Jacka: No, I wish it was that easy. A, we had very little money, so we were doing everything on the smell of an oily rag, but it was so hard to recruit people because yes, people who are very unwell and these were moderately to severely sick people with major clinical depression, they were skeptical. Their doctors and psychiatrists were certainly skeptical. We didn't get any referrals.
[00:12:32] Jonathan Wolf: Okay, so they thought they thought you were mad. Is that basically what you're saying?
[00:12:36] Felice Jacka: Completely. Completely. There was a lot of eye-rolling and all the rest of it for many years really, but we managed to do it, but we were only able to recruit 67 people, which is far fewer than what we'd aimed to recruit, and that took us three years. I mean, it was just crazy difficult. So when it came time to crunch the numbers, and we still hadn't unblinded it, and I should say that people were randomly assigned to get either dietary support, just from a clinical dietician. It was a bit like a Mediterranean diet, you know. Increase your intake of vegetables, of fruits, of whole grain cereals, of legumes. So your chickpeas and lentils and these sorts of things. Nuts and seeds, olive oil, fish. And reduce your intake of basically junk food, discretionary foods. Which people they were eating a lot of it when they came into the study.
And at the end of the three months, when we were, you know, set to crunch the numbers, and we didn't know who was in which group was just group A and group B. And we thought there is no way there's gonna be a difference between the two groups. You know, we only have 67 people. It's just not gonna be enough to see anything.
And we did the stats, and the statistician nearly fell off the chair, and we had to go and triple check the findings because we just saw a huge impact. And what we also saw was that the degree to which people changed their diet closely tied to the degree to which their depression improved. So the more they adhered to the diet, the better off they were. We also saw that it was super cost-effective because people lost less time out of role. They saw other health professionals less often. This is an economic evaluation. And finally, we did a really detailed cost analysis to show that our diet was actually cheaper than the junk food heavy diet people were eating when they came into the study.
[00:14:19] Jonathan Wolf: Is that right? Because I think that's often one of the things that people talk about you know, this whole idea is very elitist. You have to be extremely affluent in order to eat a better diet. So, it sounds like that's what you found in this.
[00:14:31] Felice Jacka: No, that's right. And this is such a key point. And I mean, we are very, very conscious of the social determinants of health, and how food has so many cultural and economic aspects to it. But what we were proposing, it needed to be really easy, because people with depression usually don't have a lot of energy, and it needed to be really affordable. Very simple.
So it was things that I eat myself every day. So, frozen vegetables, tinned fish, tinned legumes, dried legumes, like really simple stuff and very, very affordable. And I think that this is a really important point. It doesn't need to be artisan sourdough bread, you know, and organic berries and things. It can be much simpler and more affordable than that.
[00:15:12] Jonathan Wolf: And I'm sorry, Felice, just to make sure it’s clear for everybody, the final results? Because I think you had some pretty amazing results about people who went in.
[00:15:18] Felice Jacka: Yeah, we did. We found that there was a big difference between the groups. Approximately a third of the people who got the dietary support actually went on to have a full remission of their depression, which is quite unusual in you know, when you've been treated for depression. Often you're left with residual symptoms, compared to about 8% in the social support control condition.
[00:15:40] Jonathan Wolf: Which is amazing, right? You're saying a third of people came in with, you know, you're saying quite severe depression. You were guiding them on changing their diet. The length of the study was how long Felice?
[00:15:51] Felice Jacka: Three months.
[00:15:52] Jonathan Wolf: Three months. So this is a very short period of time, right? It's not for like three years, they had to follow this. And a third of them basically didn't have symptoms. And I just wanted to play that because it's really amazing.
[00:16:03] Felice Jacka: And what we've had of course is many of those original participants from the SMILEs Trial getting in touch with us. Like, a long time later and going, man, this just changed my life. You know, I'd spent years lying on the couch, crying and, and living on coffee and cigarettes and wine and massive doses of antidepressants. And now I've, you know, I've joined my local hiking club. I've stopped smoking. Now, this I think is really important. You do not have to wait forever. And when you think about the gut microbiota, which is a key focus of a lot of the work that we are doing. You can change your gut microbiota by changing your diet very quickly.
So, we suspect, although we don't know yet that this could be a major pathway by which this effect is happening. Now, if you think about the public health messages around food for so long, they've been around obesity and weight loss. And I just think that that's been a bit of a disaster because A it's stigmatizing, but B also most people can't lose weight and keep it off. There's many, many complex factors that lead to people's body weight and size. And what we know is as I said, all of our research is that body weight doesn't play a part in this role. We just need to get away from talking about that. And when you take that out of the question and you say, this is not a lot about a long term impact. You might lose weight. You might stave off a heart attack. This is about the way you can think and feel very soon.
[00:17:24] Jonathan Wolf: And that means, I guess, Felice, just to make sure that's really clear, right? That so much of this conversation has been about calories as a result of this, right? Thinking about food as calories, and like how many calories you have. But actually, everything you are doing is there's no change in the calories you're guiding these people to. It's all about the different quality of the food. And I think calories have done a lot of harm cuz it really takes the conversation away from I think, you know, and this is just another great example of how quality is much more central to thinking about what we eat.
[00:17:54] Felice Jacka: Absolutely. And I mean, it's, you know, it's that thing of you're feeding yourself. You know, I don't see why that's a difficult concept to think about, you know, us as a really beautifully built Porsche, our bodies, and we wanna put the very best petrol into it. And if we put crappy, sandy watered down petrol, of course, we're not gonna get it to run properly. So, we just need to feed our bodies you know, quality food, and it doesn't need to be expensive.
[00:18:20] Jonathan Wolf: Can we talk a bit about why we think that's happening, and I think you've just started to touch on it. And, we had a lot of questions about the gut-brain axis, so that is definitely cutting through into the mainstream. What is the gut-brain axis? Why is food having this effect? Beacuase it's not obvious, right? I eat it. It's going into my stomach, and now you're telling me it's affecting my brain. You know, what's that all about?
[00:18:43] Felice Jacka: Um, Well, there's the gut-brain axis, and then there's the microbiota-gut-brain axis. And the gut-brain axis we've known about for a long time. There's a very close relationship via the vagus nerve and all of these amazing nerves and hormones and things between the brain and the gut. About 90% of the signals go from the gut to the brain. The gut is exposed to the outside world. You know, it gets all the food coming in and it needs to be able to tell the brain when there's something bad that's gone in. But about 10% of the signals also go from the brain to the gut. We've also known of course, for a very long time that gut disorders like IBS and common mental disorders, depression, anxiety are closely related.
They're what we call highly comorbid. They seem to inform each other. And more recently, of course, we now understand that there are all these microbes in our gut that play a multitude of roles within our body. And the primary role of these microbes is to break down parts of food that our own human enzymes can't break down.
And that's primarily plant fiber, and also polyphenols from plants. And when they break these down, they release all of these molecules. Thousands of molecules that have a multitude of actions within our body. The one of the biggest of course is our immune system. Something like 70% of our immune cells are actually in our gut. But these molecules, they affect how our genes switch on and off. They affect our stress response system. They affect, I've said the immune system, but also our mitochondria. They affect our neurotransmitter systems. In fact, gut bacteria can actually produce neurotransmitters themselves. They produce lots of them. Most of them, we don't think reach the brain because of the blood-brain barrier. But what they do do is break down tryptophan, which is a part of protein in food, and that affects the amount of serotonin in our brain. So they do affect our neurotransmitter systems.
[00:20:39] Jonathan Wolf: So just to make sure I've got that right. You're saying, you know, these trillions of bacteria inside my gut are able to directly affect my mood because of the chemicals they're making that then, you know, pass through into my bloodstream.
[00:20:53] Felice Jacka: That's right. And it's not just in the bloodstream. They affect the barriers throughout your body. So that's including the gut barrier, which is really important for good immune health. Now, what's critical to say though, Is that most of the evidence from this area of microbiota-gut-brain axis research comes from animal studies.
So we know for example, that if you breed a rodent without any gut microbiome, they are very, very profoundly affected. Their brain doesn't develop in the way that it should, and their behavior is profoundly affected. There were many reasons why, based on animal studies, we know that the gut microbiomes seem to be involved in brain development and then aspects of behavior. But we have very few data from humans and this is where our food and mood center is seeking to try and address that gap. But we've just published a very large systematic literature review, and we can see that across schizophrenia, bipolar disorder, depression, people have consistent changes in their microbiota that differ from people who are the healthy comparison groups.
[00:21:59] Jonathan Wolf: And you've mentioned depression quite a lot. If people are thinking about anxiety, for example, which I know is one of the other big ones, is that the same or is this very depression specific?
[00:22:09] Felice Jacka: It's funny. The relationship between diet quality and anxiety is far less clear. Now, certainly if we look at the observational data, what we see is what we call a reverse J-shaped curve. And that is that you see this link between better diet quality, and lower anxiety up to a certain point. And then it kicks right up. And that makes all sorts of sense because people who are highly anxious are often very, very anxious about their health behaviors, and control them really tightly. And that of course actually ends up being a real problem. So we have a big issue with this eating disorder called orthorexia, where people are highly anxious and they increasingly cut out the foods that they think are bad or that are causing them gut issues, or what have you. And they get to a very, very narrow diet that is insufficient.
[00:23:00] Jonathan Wolf: That's interesting. We had a specific question actually, Felice about that, which is really interesting, which was again, you know just from our members that, which just said, knowing that the pressure around food and body image and eating healthy can lead to mental health problems. Is there any risk of using diet in the treatment of mental health conditions to actually contribute towards this?.
[00:23:17] Felice Jacka: Yeah. And so it is, it's a very, it's an area where we have to be careful. And I mean, we are running two very large, what are called effectiveness trials. So these are real world trials with people out in the community with all sorts of mental disorders. And they're receiving either diet and exercise support from dieticians, exercise physiologists. Comparing to psychological support by clinical psychologists. And the aim is not to show that one is better than the other, but to evaluate where the diet and exercise support is at least as effective as psychotherapy. And we're all super aware of just how careful we have to be around people with eating disorders coming into these studies, where it can very much feed into a mental health problem. And of course eating disorders are a very serious issue in psychiatry. I mean, anorexia is the most deadly of all the eating disorders. So there is nothing in the evidence base that says that you have to be super, super cautious with your diet. Nothing at all.
What we see across the world is whether it's a healthy Norwegian diet or a Japanese diet or Chinese diet or an Australian diet. All of these are associated with reduced depression risk after we take into account all of those other factors. All of those diets, what they have at their heart are just a higher intake of whole foods, unprocessed foods and plant foods, and a reduced intake of these unhealthy processed foods.
But we go by the 80 - 20 rule, you know, try and avoid the ultra-processed foods. But other than that, just try and increase the amount diversity of plant foods in your diet. You don't have to be a vegan. You don't have to be a vegetarian, and it doesn't have to be perfect.
[00:25:02] Jonathan Wolf: I wanna come onto that actually in just a minute to talk about the excellent advice. But I do think that what you're talking on is something we talk about a lot at ZOE. About the idea that no food should ever be forbidden. Nothing is completely off the table, and actually, it's about thinking about the total combination about what you eat, and actually, if you want to eat, you know, there are things I like, and I eat them. And it's thinking about the total diet that you put around and that's really important, and I think it's something that particularly people who are, you know, trained dieticians, talk to us a lot about making sure as we're putting this together. So I think it's really interesting that you're talking about, you know, with anxiety, we need to be careful not to go out to the other extreme and that there's a middle ground.
So Felice, on that topic, you know, I think our listeners have been patiently understanding the science and now they're like, okay, I'd really like to understand the actionable advice to improve, you know, either the health for themselves or maybe for friends or loved ones. So maybe, can we talk a little bit more about what are the foods that I should eat more of or less of if I want to improve my mood?
[00:26:03] Felice Jacka: Look, I think, you know, given the focus of the podcast on the gut microbiota, it won't surprise you to know that research in the gut microbiota and the brain psychiatry, just incredibly complicated. There's huge methodological issues with doing nutrition science, with doing psychiatric science. The microbiome is a next level complexity in terms of the very hard sums that have to be used and the processes and everything. But actually what we need to do for good mental health and good gut health are the same thing, and they're actually really simple, and this is based on all of the evidence. And that is increase the amount of plant food in the diet. And so here, we're talking. vegetables, fruit obviously, but whole grain cereals. So these are, you know, your oats, your barley, brown rice, quinoa, rye, your legumes. So these are your chickpeas and lentils and all the different sorts of beans, even if it's just as simple as sticking a tin of lentils into your spag bol.
Because the plant foods that has the fiber and the polyphenols that feed your gut bacteria. Now, most people in the west are not getting anywhere near enough fiber, and that means that the gut bacteria just can't do what they're supposed to do. And then all sorts of things happen from that. So, lots of plant food. And then, of course, diversity. The more diverse your diet, the more diverse your gut microbiome. And whilst the evidence is not completely set on this yet, it does look like, having a more diverse gut microbiota is a more healthy and robust one. And if you think about a rainforest, a healthy rainforest is one that has a huge diversity of plants and creatures that are all supporting in microbes. That are all supporting each other to grow and be resilient. Whereas, a single crop monoculture is far more vulnerable to, you know, a particular pest species coming in and just wiping it all out.
Avoid the ultra-processed foods. So the foods that come in packets that have a multitude of, you know, names and numbers and things on the back. Avoid things that have been highly processed. And we would say, chuck in a bit of fermented foods. The evidence for that is still not strong, but on the basis of what we do know, and all of the knowledge about fermented foods and how they've been part of traditional cultures throughout history. There was a very cool study, very small sample size, but it was a very cool, interesting study just recently that showed that increasing the number of serves of fermented foods a day in the diet led to a reduction in inflammation. So fermented foods are things like kombucha, kefir, yogurt, all of your, you know, like sauerkraut, you know, fermented veggies of different sorts. Kimchi, Tempeh. These are all fermented foods. So if you can try and get some of those into your diet as a regular thing, and you can make a lot of these at home for almost no money, which is very cool and kind of fun.
So it can be really that simple. So increase the good stuff, decrease the bad stuff, possibly throw in a bit of fermented foods.
[00:29:13] Jonathan Wolf: And, Felice we had a number of questions around some more specific situations and the most common one, not surprisingly is around menopause where mood is one of the things that can obviously be affected through this. Is this something that you've looked at all? Is there anything specific that people should be thinking about here?
[00:29:32] Felice Jacka: Look, menopause sucks, as someone who's been through it. Its impact is just not discussed anywhere near enough. I mean, it's very, very challenging for a number of years. It profoundly affects people's sleep a lot of the time, and that has an impact on their mood, on their eating behaviors, on their health, and many different aspects of their health.
But women tend to put on about five kilos without doing anything different. They could be eating the same, exercising the same and just suddenly. You know, they've got all this extra weight. Things really change very quickly when you go through menopause. You sort of go from one state to a completely different state in a very short period of time. So, it's really not surprising that people experience hits to their health, mental health as well. And avoiding alcohol, I think is a really useful way of cutting down energy intake, but also really having a benefit to your physical and mental health.
And I say that as an ex drinker and someone who really liked wine, a lot, and realized that it really wasn't serving me well over menopause. And then with the breast cancer diagnosis and treatment, even more reason to stop drinking alcohol. So yeah, menopause sucks. It's really challenging.
[00:31:00] Jonathan Wolf: And otherwise, your advice basically remains the same thing that at this point, what you haven't yet got is a personalized advice around different sorts of mental health or, you know, mood that might be affected by big physiological changes like menopause at this point. We're sort of on a generic sort of, very gut-friendly diet.
[00:31:18] Felice Jacka: Yes, at this point. So the field of nutritional psychiatry research is only about 12 years old. So there's a lot of work to do and certainly, we're developing the tools and the strategies to start to understand how it might be personalized and to test whether or not that's going to increase its ability to help us improve our mood. But at this stage, all the research evidence from right across the world and right across the lifespan tells us that it just needs to be a diet that's higher in whole foods and plant foods, and lower in processed foods. And that, that is pretty much the same for everyone.
[00:31:54] Jonathan Wolf: And I was talking to you before we started recording about trying to get you more involved in the ZOE program of research. To look at how we can think about personalization against this, because, we see these huge variations in responses to everything, and so I think we would expect to see the same in terms of this.
So, there are so many more questions here, but I did want to touch on one other topic before we run out of time, because we had lots of questions about the sort of the other way around. In other words, how does our mental health affect how we eat? And I think probably all of us have experienced this, right? So, I'm lucky. I haven't suffered from depression, but I'm very conscious that, you know, I have periods when, you know, I have low mood for various reasons, and it completely changes the way that I think about food. And I think for many people, there's a lot of concern about self sabotage of this healthy diet. It's great. I stick with it for a while, and then something knocks me and it feels as though our body is really craving things that Felice, you're just telling us are really bad. Is this real? What's what's going on?
[00:32:57] Felice Jacka: The evidence that mental health affects our dietary choices is not as strong or as extensive as people assume. However, when we're upset, stressed, you know, experiencing strong emotions, we seek things that give us some short term comfort. So that might be internet shopping. It might be drinking half a bottle of wine. It might be smoking a cigarette. And food falls into that category. And what we know is that the industrialized food system is sort of the largest industry in the world. Its impact on our global health and the environment is almost equivalent to that of the whole GDP of China every year.
It's the leading cause of early death and illness. And “Big Food”, like these big, fast food purveyors. They spend millions of dollars designing food products to deliberately interact with all of those reward systems in the brain - our dopamine regions of the brain. So we get a short term hit, a short term comfort when we eat these sorts of foods. But the long term impact is the opposite. So very much like smoking or drinking, taking drugs. Short term impact versus long term impact. And so we put them in the same category.
[00:34:15] Jonathan Wolf: Is this true? Because people talk a lot about this food triggering these things, and you mentioning like dopamine receptors. I don't really know what that is. Could you explain? I think people are really interested. Go on.
[00:34:27] Felice Jacka: Anything that gives us pleasure that, you know, triggers these reward systems in the brain, which sort of strengthen our brain pathways to try and get us to do it more often. So our brain is going, I want more of that. I wanted more of that pleasure. Give me more of it. So, we're not talking here about addiction, like a drug addiction or anything like that. We're just talking about things that give us pleasure. Now, those things that give us pleasure can be healthy. They can be going for a walk or doing some exercise or something, or, you know, hugging someone we love, but they can also be things that are not particularly good for us. And, junk foods can fall into that second category of giving us pleasure and reward, and so our brains want more of it. But it seems as if these ultra-processed foods somehow seem to bypass some of our body and our brain's natural systems for controlling our appetite.
So there's all sorts of reasons why we want to go to that drive-through when we've had a really stressful day, or we're feeling really low because they are designed to give us that boost, and so that we keep coming back for more.
[00:35:34] Jonathan Wolf: It's amazing. So, this stuff has been carefully engineered to sort of trigger these, sort of feedback loops within our brain. And sometimes we hear this, but what you're saying is, this is real. The science has shown this. And so then maybe we should give ourselves a little bit of a break. That this is not all about our poor self control. You're in an environment where lots of very smart people have created things that are designed to take advantage of these systems.
[00:36:00] Felice Jacka: You know, in Australia only about 5% of adults adhere to the dietary guidelines, and less than half a percent of children eat the recommended amount of vegetables and legumes. Now, this is in a country where we have widespread availability of good food. Not everywhere, not out in the far regions, but in most places. And, you know, we have a big spread of education and income. And so this is not just something that affects people from a low income background or low education background. Everybody is eating really, really badly. Why is that? Because the industrialized food system is set up to make a profit from people eating that way rather than as we used to eat.
But knowing that this is something that you can do for yourself and your kids that puts the power back in your own hands, that may help to prevent mental illness starting in the first place, and treat it when it's already in situ. That is very powerful, and what we see over and over again is that people love that that this is something they can do themselves and they can, and they do improve their diet quality.
[00:37:06] Jonathan Wolf: Amazing, well, I think it's clear where you stand on the role of “Big Food” in all of this Felice
[00:37:13] Felice Jacka: It's what gets me out of bed in the morning.
[00:37:15] Jonathan Wolf: Well, we are very excited to see all the new studies that you're working on because you're getting out of bed in the morning. I think at this point, there are so many other questions I wanted to ask. We're gonna have to try and save that for another time if we can tempt you back. I'd just like to try and summarize what has been a very wide ranging conversation, and correct me if I've got any of this wrong, please.
So we started by just saying depression and anxiety are very common. Historically, psychiatry only looked at what happened from the neck up. So there was very little study of the impact of food or really anything else happening to the body on mental health. You've then done these amazing studies and seen this huge impact from changing diets on depression. And I think you said that 30% of people had no symptoms after three months of following this intervention.
[00:38:03] Felice Jacka: Yeah, well they went into what's called remission. So they met the criteria for remission.
[00:38:09] Jonathan Wolf: Met the criteria for remission. And that you've done some follow up studies where actually you saw impact even within three weeks on people.
[00:38:16] Felice Jacka: Yes. I didn't lead those studies, but others have done that.
[00:38:19] Jonathan Wolf: Brilliant. So there have also been studies showing even shorter periods than three weeks. And that in terms of why, there's this gut-brain axis, which means there's a very tight link between the gut and the brain. You said many gut disorders like IBS and mental health are highly linked. And that increasingly the evidence shows that it's the bacteria in our gut are a very central part of that, and actually can directly impact our mood, which is, amazing and that indeed, when you look at people with certain mental health disorders against those without you can actually see, different gut microbiomes between them
[00:38:53] Felice Jacka: mm-hmm yep.
[00:38:54] Jonathan Wolf: We then we then touched I think on why do we crave bad food when we're stressed? And I think you said like when we're stressed, we're seeking things that give us comfort. Food is a really classic thing that falls into this category. And then we're in this environment where “Big Food” has provided these foods that give us a short term boost for something that's really pretty bad for us. So we're sort of grabbing this thing that's been very carefully created to give us this biggest boost, but sadly not optimized for our health. Is that a good summary?
[00:39:22] Felice Jacka: Yeah, that's a great summation. And just to say that the evidence in this field of nutritional psychiatry is now reflected in more than 80 very high level policy documents around the world. And it's now informed really profound changes to clinical guidelines in psychiatry, such as in Australia, the Royal Australian New Zealand College of Psychiatrists, the guidelines for treating people with a depressive or bipolar disorder have essentially lifestyle medicine. So addressing diet, physical activity, sleep and smoking and other substances. So there's a lot that's happening in the policy and practice area, which is really important.
And if people wanna know more, we've got our food and mood center website. Has lots of blogs, lots of info, lots of links to the science. So there's lots of ways of finding out more information.
[00:40:09] Jonathan Wolf: Brilliant. And if I just finally conclude with what you can do to summarize. Increase the amount of plant food, vegetables, fruit, whole grains, legumes, which are beans, basically, diversity of different foods, so you can't just pick three of these things. You're trying to get a lot of range. And then avoiding ultra-processed food. And then in terms of fermented food, there's no real evidence yet on mental health, is what I think I understand, but we know that there's some really interesting evidence for that for microbiome, in general. So it can't do you any harm and it's something interesting. And then I think finally we said, you know, during menopause, you said in addition, think about reducing alcohol as something you think can be positive.
And then specifically, last thing I think is with anxiety. I think you said we need to be careful here. That's a little different from depression. We absolutely say you should be looking to improve your diet, but we don't want to get into a place where actually you're sort of pushing towards disordered eating with too much control.
[00:41:05] Felice Jacka: That's exactly right. Beautifully summarized.
[00:41:08] Jonathan Wolf: I'm glad. This was an incredibly exciting area, I think. And, and I think what's also clear is there's so much research that's going on right now, looking at the links between gut microbiome and mood and these sorts of interventions. So it sounds like there's gonna be lots of new things to talk about in the next few years.
[00:41:25] Felice Jacka: Yeah, definitely. Watch this space.
[00:41:28] Jonathan Wolf: Wonderful. Well, I hope you will come back in the future and we can talk about some of those new results.
[00:41:32] Felice Jacka: I would love to.
[00:41:34] Jonathan Wolf: That was brilliant. Thank you so much, Felice. Thank you for taking the time.
[00:41:37] Felice Jacka: Such a pleasure.
[00:41:39] Jonathan Wolf: Thank you to Felice for joining me on ZOE science and nutrition today. We hope you enjoy today's episode. If you did, please be sure to subscribe and leave us a review as we do love reading your feedback. If this episode left you with questions, please send them in on Instagram or Facebook and we will try to answer them in a future episode.
At ZOE we want to improve the health of millions by understanding the right food for each of us to improve our health and manage our weight. Each member starts with an at home test, comparing them with participants in the world's largest nutrition science study.
If you're interested in learning more about ZOE, you can head to joinZOE.com/podcast and get 10% off your personalized nutrition program. As always. I'm your host, Jonathan Wolf. ZOE Science and Nutrition is produced by Fascinate Productions with support from Sharon Feder and Alex Jones here at ZOE.
See you next time.