ZOE Science & Nutrition - 4 immunity tips for healthy ageing | Dr. Jenna Macciochi

Episode Date: October 31, 2024

Over the last two years, there’s been a rise in “immune-boosting” foods, supplements and trends. Today's guest, immunologist Dr. Jenna Macciochi, believes the immune system doesn’t need boosting. Instead, it should be balanced. In this episode, Jenna - a Senior Lecturer in Immunology at the University of Sussex - reveals how your immune system is your body’s housekeeper. Jenna highlights the case for the ‘good bugs’ in our gut microbiome, the role of micronutrients and how our immune system isn’t born, but made. We'll also tackle the age-old question: do we really need Vitamin C supplements? 🥑 Make smarter food choices. Become a member at zoe.com - 10% off with code PODCAST 🌱 Try our new plant based wholefood supplement - Daily 30+ *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system Follow ZOE on Instagram Timecodes: 01:21 Quickfire questions 04:51 What is the immune system? 06:49 How your immune system works 09:35 What are natural killer cells? 14:18 Is your immune system inherited? 16:42 The impact of sleep and stress  19:53 Cancer and immunotherapy 28:23 This can trigger inflammation 30:25 Are vitamin C supplements worth it? 31:30 Foods to empower your immune system 40:10 How inflammation affects your brain 44:10 New science of the impact of stress 48:52 Immunity and your body clock 📚 Get Jenna's book Your Blueprint for Strong Immunity 📚 Books by our ZOE Scientists: The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati Food For Life by Prof. Tim Spector Mentioned in today’s episode: “Immune Boosting” in the time of COVID: selling immunity on Instagram (2020), published in Allergy, Asthma & Clinical Immunology Vitamin C for preventing and treating the common cold (2013), published in Cochrane Database of Systematic Reviews Effects of stress on immune function: the good, the bad, and the beautiful (2014), published in Journal of Immunology Research Have feedback or a topic you'd like us to cover? Let us know here. Episode transcripts are available here.

Welcome to ZOE, Science and Nutrition, where world-leading scientists explain how their research can improve your health. In the last two years, there's been a surge in Google searches containing two words. Immune Boost. Immune Boost. And what's followed has been a wave of brand new products. Detoxes, supplements, superfoods. All claiming to provide this potentially life-saving immune boost. But what does boost actually mean? Is it even possible?

And could our desperation for a quick fix be doing more harm than good? for a quick fix be doing more harm than good. Dr. Jenna Michoki joins us today to separate fad from fiction. Jenna is a senior lecturer in immunology at the University of Sussex, an author of The Science of Stain Well, and your blueprint for strong immunity. You'll leave this episode with an evidence-based approach

on how to support and maintain a healthy immune system. Jenna, thank you very much for joining me today. Thanks for having me. It's great to be here. So we have a tradition here at Zoe, which I think we might have warned you about, where we always start with a quick fire round of questions from our listeners.

And this is designed to be super hard for professors because you are only allowed to say yes or no. If you absolutely have to, you can give us a one sentence answer. Are you willing to give it a go? Yep, let's go. All right. Can I improve my immune system without taking drugs? Yes.

Is the immune system mainly to fight off illness? No. Should you try to boost your immune system? No. Will taking vitamin C supplements reduce my chance of getting a cold? No. Can my emotions make me ill? Yes.

And last one, you can have a whole sentence. What's the biggest misconception about the immune system? I'd say that if you get sick, you know, we're going into winter, seasonal viruses are around. If you get sick, it means you've got a rubbish immune system. Well, you know, that's brilliant, because that's literally what I wanted to start this with. So I was thinking about my experience when I was a kid. Both my parents are complete workaholics, but the setup was also quite traditional.

So my mom was always the person who would pick us up from school. She was also sort of looking after us. And I remember like every few months, basically, my mom would just sort of collapse at the end of the day or when she came back from work, like go to bed. She's like, I feel really terrible. And for 24 hours, she'd be wiped out and then she'd sort of pick herself up and keep going. And my dad basically never got sick. So when a virus hits our house, everyone in the family gets it.

I've got children as well. And my wife, who's a doctor, she gets a little cold. She says it's nothing and she just keeps going. And I often feel like I'm wiped out. It's like five days until I feel like I probably got better. So I'm just basically really curious around, you know, have I just inherited my mother's terrible immune system? How much of this is about like the stress that I know that, you know, I put myself under and that I feel? And so I'm really hoping that you can unpack this for us.

And at least I will learn something, but I'm hoping some of our listeners have some similar sort of anecdotes from their lives. I think that's something that all of us can relate to. And it also speaks to how complicated the immune system is because you've hinted a little bit about genetics. Is it that I've just inherited this? You hinted a little bit about stress. There's also gender differences and how we respond in terms of our immune system. And there's the exposure piece. So we often tend to think it's our immune system's rubbish.

We've got sick. Oh my goodness. But it also comes into play to this bigger equation of how much exposure you get. Perhaps because your mom was the sort of primary caregiver of children, like she's getting more exposure to kids. Kids are little germ factories because the sort of basic hygiene is sometimes a work in progress. That is for sure. So, you know, that's part of the equation. Genetics are part of it.

So you will have inherited immunity genes from both your mom and your dad. Now, the interesting thing about the way that we inherit those genes is that you will get a set from both mum and dad. Jenna, before I dive more into that, I want to pull us back for a second because we're already talking about the immune system, but actually I don't understand what the immune system is at all. It's like one of those words that I use, but I don't understand it. What is it?

It's hard to grasp. And we talk about it as one thing. And if I asked you to say like, where is your digestive system, you could probably point to the location on your body. If I ask you to point to where your immune system is, you might not know where. I'm literally like, I don't. Yeah, that's because it's everywhere. Okay. From your brain to your big toe, it's absolutely everywhere. And that's because essentially it's helping keep your body safe.

So it has to be everywhere. It's really enriched at the barriers to our body. So, you know, under your skin, because that's exposed to the environment, the lining of your nose, the lining of your mouth, all the way down your digestive tract, you have huge numbers of immune cells that are fortifying those barriers because those barriers are very delicate. So the airway lining and the digestive tract lining, they're very delicate and that serves a function that helps us exchange oxygen when we breathe, it helps us digest our food and absorb nutrients, but we need to have that extra fortification because that's vulnerable.

You know, we can inhale germs or swallow germs and that could make us sick. So you will find immune cells everywhere. They're also swimming around in our blood, so they're performing a kind of surveillance function. And then you have immune organs where they'll like congregate and do a certain function. So we have lymph immune organs where they'll like congregate and do a certain function. So we have lymph nodes, which are all over our body, and they're all connected with the lymphatic system. That's kind of like your blood circulatory system,

except it doesn't rely on the heart to pump it around. So it relies on your muscles moving. And the lymphatic system is going to squeeze those immune cells around, allowing them to circulate all over your body and they pass in and out the lymph nodes and that's a place where they can meet and talk and do various functions. It's a beautiful picture. I'm starting to think about all this around me. You've mentioned the word immune cells quite a lot when I've asked what is the immune system. Is the immune system like a set of immune cells?

Yeah. Immune organs, lymph nodes, spleen, bone marrow, and the molecules that they're producing to communicate with each other. So you've got cells, molecules, and then organs. I think we all know that it's got something to do with dealing with viruses and bacteria and things like this, but I think at that point, most of us are drawing a big blank. Could you help us understand a little bit more what it does, how it works? It's hard to conceptualise because it is this kind of galaxy of things spread out throughout our body.

But within this collection of immune cells that I've mentioned that are swimming around in your blood and lymphatics, congregating at all those body barriers, there's many different flavours of immune cells that I've mentioned that are swimming around in your blood and lymphatics, congregating at all those body barriers. There's many different flavors of immune cells, and they each have their own specific set of functions, and then they'll collaborate with other cells to do certain jobs. Because if we think about it through the lens of infection, there's many different types of infection. Viruses look different from bacteria, which look different from parasites. So we have, over the evolution of the human race, developed all these different immune cells to try and cope with the multitude of different infections that could try and get in our body and harm us.

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what you think of it. Okay, back to the show. Is it just for dealing with colds and flu and nasty bacteria or is there more to it with the immune system? I mean, part of the message that I love to share is that there's so much more to our immune system and I think I've been very passionate about this subject for a long time, but I got kind of bored with just seeing it in the media being talked about as something that we think about when we get, you know, those familiar symptoms of a cold or flu because it does so much more than that. But I think the infection is something that people are familiar with.

We can identify with the last time we caught a cold or a flu and the feelings that we experienced when our body was dealing with that. So this is part of our immune system's weaponry. It's a very first line defense. So it's kind of like going out to battle, but not very specific. It's just like, oh my God, there's a problem. You know, there's a viral infection in the lungs. Send in all the troops.

They're not very specific, but they're just going to try and like deal with what's there. So you know, you're unfortunate enough to inhale a whole dose of some respiratory virus, for example, those viruses are going to infect the cells that line your airways, the cells that you use for breathing, for gas exchange. And by virtue of those viruses being in the cell, the cell is going to start to put out little red flags on its surface to say something's up here. And that is a message to our immune system that something's wrong. So our immune cells are sitting there in the airways making sure everything's nice and healthy. And as soon as they see one of our barrier cells of our

airways put out that red flag, it's like, oh, right, there's a problem. They're going to go in and start killing our own cells that are infected, which sounds quite dramatic, but that's to stop the virus from spreading. You said the cells say, hang on a minute, I'm getting infected and our body immediately goes out and kills our own cells as a response. Yes. Very sort of Game of Thrones. It is, yeah. Imagine zooming in to watch that unfold. But we have cells called natural killer

cells. That's not a joke. That's the actual name of our immune cell. And that's because they are natural killers and they have that ability to identify our own cells when they're damaged or transformed into something that's stressing them because they're trying to remove that damaged cell before the infection can spread. Because when a virus enters our cell, it turns it into a little viral replication factory so that it can burst out with hundreds more viruses, so you get this exponential infection. So we're trying to get on top of that before it can take off too far.

That's amazing. So we're sort of like, we're killing our own body every time I have a cold. If you're traveling on the tube, you know, and you're breathing in all sorts of things, this is probably happening at a minute level all the time before it even gets to the stage where you get symptoms. So there's a collateral damage. And this is an evolutionary trade-off, you know, in order to survive in a world that is filled with microbes, there has to be that trade-off. And inflammation, really beneficial, that's in the lungs, all these different chemical messengers from our immune cells to recruit in more backup troops to help deal with that

before it becomes really, really a big problem for your body and you compromise the function of the airways. So you get pneumonia and you can't breathe properly. So we're trying to stop that happening, but we have to deal with the fact that there's some collateral damage. So your body is going to make some adjustments. And if you remember the last time you had a cold or flu, you might have felt a little bit poorly, low energy, a fever, maybe some social withdrawal, maybe loss of appetite. And this is because your immune cells are putting out chemical messengers that are acting on your brain to change your behavior. And these are called sickness behaviors because we don't want you with your infection going about your daily life, walking down the street,

going into the office, speaking to people, because A, you're gonna spread that infection, and B, you're consuming energy that your body could instead put into getting well again. And I think this herein lies the problem in the modern life, the world that we live in. How often do we just get up in the morning, feel lousy, but we'll go to the pharmacy,

take all the things that suppress the symptoms, i.e. suppress the immune response, so that we can go to the office and show up to work and, oh, I don't have a cold. And essentially, treating those symptoms is stopping your immune system doing its job. What we should be doing is listening to those sickness behaviors, having maybe one day on the sofa, getting lots of rest, because activating the immune response, activating that inflammation that's fighting off the virus, is a really energetically costly thing for your body. So every one degree of fever that your body temperature rises, your basal metabolic rate is going up about 10%.

You have a certain energy cost to running your body. So that's why we have to consume calories and then we obviously expend calories going about our daily life and all the different functions that are happening in our body. When you have inflammation and you're feeling all those sickness symptoms

and you're fighting off an infection, your requirement for energy is going up because your body's going to triage more of that energy into the immune system. There's sort of like a metabolic switch that says, okay, person's going to feel tired because we need that energy for the immune cells. So therefore, if you try and go and do some exercise,

you're probably not going to have the same capacity as you would when you're healthy. And your body is sending all of these signals because it basically says the best way that I can get better as fast as possible is to tell me to stop doing all those other activities so that I can sort of devote my body's resources to fighting this thing and maximize the chances that I can defeat it. Yeah, 100%. And also because it stops you spreading the infection.

So there may be something like that that's dialed in through our evolution as well. I remember again, as a child, it's like, oh, well, you can't have the same thing that, you know, I have because, you know, you've got those cold symptoms and I just feel really tired. So obviously it's a different bug. But it seems like it's not as simple as that. What is the link, I guess, between the symptoms that I have? You know, how much is that the virus? Is that my own immune system? Why is it, I guess, coming back to my mom and dad, that she might be flat in bed for 24 hours and my dad, you know, must be exposed

to it, I guess, if they're in the same room and seems to sail through. Yeah, it's interesting. And there will always be a genetic component, so that's going to be one element of it. The way that your immune system can identify that infection and how quickly it can respond, that's definitely something that can be determined by our genetics. But then there'll be other things at play as well. And that can be, you know, everything from your health status, you know, how stressed you feel, how well you've slept or not. For example, after

I had kids and I went back to work and my kids were in nursery, you know, they were bringing home so many colds and flus as it happens when you have a lot of kids mixing together. And I remember they brought home a cold and everyone in the house got the same cold. And for a few days, we were all feeling really lousy. But I was this new mom coping with like this transition in my life and I didn't slow down. I didn't stop. I was still going to work and yada yada. And then I ended up with pneumonia

because I was really stressed. That's terrible. Everyone else got better from the cold, but I didn't. Is your explanation that you didn't rest or that your immune system was more compromised? I mean, I think it's a combination. And obviously this is an N of one experiment. Which is science speak for saying it wasn't a full trial. It was an observation case study of myself. We are on a podcast, so the floor is yours.

I can declare that upfront. But if I sort of zoom out and remember that time in my life, and I wasn't sleeping very well, I had twins, they were still small, still fragmented sleep, and I really found that transition to being back at work difficult. And I didn't rest because as a parent and, you know, juggling work, there isn't always that time. And I do believe that that was important in what happened next because the, this lack of sleep, this stress, that's sort of an ongoing stress.

Um, and yeah, not resting, not listening to those sickness behaviors. And Jen, how would the lack of sleep and the stress affect your immune system? Because again, I can hear my, I can definitely feel like, hear my grandparents would have been like, you know, that's all in your mind. Just like, yeah, you know, get on with it. So that would all just be like being sorry for yourself. Is there actually real science that that actually has an effect on your immune system? Yeah, there is real science.

And this is where it starts to get complicated because, you know, we've spoken a little bit about genetics and a little bit about sort of other lifestyle factors like rest and things. But actually, the immune system is the sensing system, so it's really in tune with what you're doing within your daily life. And it's taking in all that information and calibrating and trying to reach a point that's going to be useful for you at that moment. So it's really affected by stress chemistry. So we tend to think of stress as being something in our mind, but also we know that there's biochemical responses that happen within our body when

we feel stressed. And our immune cells have receptors on their surface for those stress chemicals. So they're going to be responding to how we feel in the short term that actually helps the immune system. So if you imagine if you're about to walk out on a busy street and you didn't look properly and you're about to be hit by a car, you get a surge of adrenaline, you're going to run to safety. That stress chemistry is going to provide you with that instant energy and focus that you need to get out of the way. It's also going to prime your immune cells to respond in case of an injury

where there could be an infection. So in the short term, it's also going to prime your immune cells to respond in case of an injury where there could be an infection. So in the short term, it's helping your immune response. But then over the long term, you get things like cortisol, which is an important player in the stress response, and that's going to have a suppressive effect on your immune system. So prolonged stress, we know, can make you more vulnerable to infections. And I don't want to get too miserable. And we will definitely come on to all the good things you can do to make things better. But I'd like to just sort of follow that thread to what scientists understand now

is the impact of your immune system on your long-term health. Because I've heard people talk more and more about how it's not just for sort of like this protecting you from a virus, but it could have an impact on your long term health. Is that right? And what? Yeah, I mean, I think it's really good to start by just thinking about our immune system in a different way.

So we've spoken about infections and that's probably the way that most people are familiar with this, you know, thing that we call the immune system. But it does so many other jobs. You know, imagine if you were to break a bone and you don't have any infection there, but you've got damaged tissue. Again, just the virtue of tearing up some of your tissue is going to bring those immune cells in and they start to repair damage.

So they're constantly doing this repair mode. They are our main cancer surveillance system. So this is something again, people aren't aware of that your immune cells, you have specific immune cells patrolling your body all the time, looking for cancer or potentially cancerous cells and removing them before they become a problem for your body. Which is amazing.

It's amazing, yeah. And that's what has birthed, you know, the immunotherapies that we see coming out now, which are being used to treat cancer. So it's helping our own immune system to identify a tumor and attack it, rather than just relying on the traditional slash burn poisons or surgery, radiotherapy, chemotherapy, where we're having

to bring something in that attacks the tumor when we have an immune system that has evolved to be able to identify and attack tumors. So it's a really amazing bit of science that is going to change how we deal with cancer. And so does that mean that if I have like a poor immune system, maybe you're describing the stress and everything else that might mean that it's not functioning as well as it should, does that increase my risk of cancer or other long-term diseases? I think that's a hard question to study and a hard question to definitively answer, but we do have clues from the literature that people who suffer with certain conditions have higher risks of cancer.

So there is a link there, but I think those real kind of longitudinal studies we haven't done yet. But I think that's something that because we have now this much longer life course, we definitely need to be looking at. And then I'd love to ask you a bit about the microbiome, because my co-founder, Professor Tim Spector, has sort of discussed with me and on this podcast that we now understand that an important part of what the immune system is doing is actually sort of managing all of these microbes in our gut, which in this case are not bad for us, they're not toxic.

They're somehow like an essential part of how we're meant to be. Yes. Isn't that right? And what's going on? How well do we understand this? Because I know that everything around the microbiome is quite new within science. Yeah, it's quite new, but so exciting.

And it almost feels to me like it's been the missing piece in the puzzle of understanding our immune system. I mentioned earlier that a lot of our immune cells are congregated along the digestive tract and That's where the bulk of the microbes that we carry are as well so you think about the inner tube of our digestive tract having all these microbial communities living there and Then you have the gut barrier wall and on the side, you have lots and lots of immune cells. And so this gut barrier wall is a really important interface between what's happening in the gut with these microbial communities and what's happening on the other side with our immune cells.

And so there's a crosstalk that goes on all the time. And we now understand that when a baby is born and they start being colonized through all the microbes that they're receiving during the birth and then the first few years of life that those microbial communities are able to directly influence and train and educate our immune system. And so having the right mix of microbes is going to be really important for that education piece to take place. And it happens in the gut, but then it spreads throughout the body,

so it's not just localized in the gut. And we've spoken a lot about inflammation and the sort of fighting arm of the immune system, and there's a lot of kind of military analogies that people will use. But I think one thing that's forgotten about is that you have to have the peacekeepers as well. So you have to have the part of the immune system that comes in and turns things off when they're not supposed to be on, that clears up the damage and keeps the homeostasis within the body. And this is where this relationship with the microbiome was so important.

So the microbiome are eating what we eat, and they're breaking that down, and their kind of metabolic waste products, I guess, are then going to be absorbed into our body. So there's one molecule, for example, called butyrate. Butyrate is produced by specific microbes when they eat specific fibers in our diet. And butyrate is important for various aspects of immune function. So it can directly act on immune cells to turn them into what we call T regulatory cells or Tregs. And these are the key peacekeepers.

These are the ones that are going to shut off unwanted immune responses. We know that they're really important in things like preventing or reducing allergies and autoimmune diseases. So these are conditions where our immune system has gone wrong and started chasing a target that actually isn't damaging at all. That's amazing. And one of the things we know, I think, is that we're eating diets that are very different from the diets we ever used to eat.

You know, very little plants and fiber, lots of ultra-processed food, and therefore what we're feeding these bacteria is very different and most of us are not getting the amount of fiber that we would have done. So does this mean that, you know, in the past, those bacteria would have been creating this butyrate that you're talking about and switching on this peacekeeping and now, for most people listening, this is probably not happening in the way that, now, for most people listening, this is probably not happening in the way that, as it were, nature intended? Yes. It often feels like this system has been designed, that these microbes are our allies, and they're producing things that are so critical to the proper development of this part of

our immune system. And when we're born, our immune system is actually quite underdeveloped. So a bit like the brain, you know, it has a lot of its development happening in those first few years of life, particularly in the first two to three years. And that's when we have a lot of changes going on with the establishment of our microbiome. As the baby, you know, explores the new environment, whatever the feeding practices are, and whatever the diet is. So you have very early on a trajectory being set in terms of that regulatory arm of the immune system. And when we look back through history, you can see that there is a strong correlation with the use of antibiotics from 1950s. Then we started having more convenience foods, ultra-processed foods, dietary fibre

intake drops, and this correlates to the explosion that we see in things like allergies, autoimmune diseases and inflammatory diseases. It's all kind of happened so very quickly, and now we have this problem where we're trying to figure out how to get back to where we need to be. Hi, I have a small favour to ask. We want this podcast to reach as many people as possible as we continue our mission to improve the health of millions. And watching this show grow is what motivates the whole team at Zoë to keep up the really hard work of creating new episodes each week. So right now, if you could share a link to the show with one friend who would benefit from today's information, it would mean a great deal to me.

Thank you. I think this idea that these tiny, tiny little bacteria might actually be training our immune system in the first couple of years is completely crazy when I think about anything that I knew until 10 years ago. Yeah. And really interesting to hear from you with your expertise really in the immune system. I'd love to move on now and pick up on the question that you talked about at the beginning that I think will have shocked a lot of people where you said immune boosting is bad. Why isn't this a great thing?

I mean, if you think about it, it's not a switch that we just want to flip on because the on is what we mentioned in the beginning. That's like tearing up your lungs with inflammation to fight off a virus. So it's really about this balance. And I think that we kind of think about it all the wrong way. We want to have something that will make us invincible to germs. And we live in this really germy world, you know, where they're everywhere. There's no way to be invincible, but we have to be robust and resilient to

germs. And that means that our immune system has to be able to respond well, but also do the peacekeeping as well, keep things under wraps when we don't need inflammation. So it's, inflammation is such a damaging thing for our body. It should only be unleashed when we really need it. And we know that not getting enough fiber, not looking after those gut microbes, things like that can actually increase what we call unwanted inflammation. And this is driving age-related disease. So across the life course, rising levels of unwanted inflammation makes us more prone

to age-related disease, things like type 2 diabetes, heart disease, certain cancers, frailty, and we want to be able to counterbalance that. So we don't necessarily always want this inflammatory response, this immune response to be on. It just doesn't make sense to me in my head. It's yeah, we want to have the balance. We want to have responses when we need it. But generally when we're not fighting an infection, we want the immune system to be off. We want calm and quiescent immune cells that are not spitting out inflammation. So the boosting part just doesn't make sense.

Your body is jumping on everything when actually it could have just let it slide by and it's triggering all of these like very strong responses. when actually you're saying for many of us it would be better if our immune system was a bit more relaxed, not like moron. Exactly. Because I think there's so many things that trigger unnecessary inflammation, you know, stress, per diet, like exercise, like pollution, like the list is endless. And actually we want to be turning that off as much as possible. So boosting, it's like which bit are you boosting for how long, for how much,

like because the immune system is this huge constellation of a million different types of cells and molecules. So to shrink it down to an on-off switch to me, it's like it doesn't make sense. And I think it's just what I call immune washing. So people are taking advantage in terms of marketing terms, you know, because people are scared. You don't want to get sick. You want to get through winter without having to take time off work. And there might be something that contains a certain amount of vitamin C, which means they can use that immune boosting wording on their packaging, but it's not going to make you invincible to a germ.

Could we talk directly about that? So if I take vitamin C, is it going to make my immune system better and mean that I am going to be sick less? I would love to say yes, but if you have a really good diet, I would definitely save your money. There is some evidence that if you, perhaps you do a lot of running or a lot of sports and you're under a lot of stress and in those cases you might need a little bit more than you're getting from your diet and that might prevent incidents of illness but we're talking really small.

And there's some evidence that when you start getting those symptoms you think, oh I've got a bit of a tickle in my throat or I feel a bit, you know, flu-y today, that your immune cells suddenly need so much more vitamin C. And if you start supplementing at the onset of symptoms, you might reduce the duration of the infection. And that's because vitamin C acts as an antioxidant. And because inflammation is basically a big oxidative stress, so it's full of free radicals, it's damaging your own tissues, your immune system is like, I need way more vitamin C right now because it's a great antioxidant. But you know, I think the evidence is so small. Maybe keep it in your cupboard, you know, and in winter, you know, it's something you could start taking

if you fall sick. You're saying this, but I'm looking at you and you don't look like you believe that I should be taking vitamin C. There is evidence there. But to me, I think the rest is probably a better way to, you know, that's where I'd put my money. Have an afternoon on the sofa, don't go into work, get some proper rest, you know, eat some really nourishing food, like delicious soup that's packed with, you know, lots of lovely vegetables and fiber and have an orange, things like that, fruit and veg that's full of vitamin C. And the citrus by flavonoids and the flavonoids

that are wrapped up with the vitamin C in food is going to actually help it work better and get into your body. So I'm kind of a food first person, but if you want to have a protocol based on the science, you could take a gram of vitamin C and spread it throughout the day with a supplement. And what about other supplements? There are various other supplements that people sell and say that you're going to take this thing and it's going to make your immune system better. What does the evidence say about that versus like being able to improve the overall diet and the things you were talking about before.

I think there's two things we're thinking about here. One is that we often have a reactive approach to it. So we don't think about our immune system going through our daily life, get into winter, first virus hits us, and then we're like, oh, I've got such a terrible immune system. And then we take all the things that tell us they're going to make us better. I like to think about it in more of prevention in that looking after your immune system so it can look after you is a 365 day a year job. And that's, you know, what we should be doing every day, not just waiting till we get those symptoms and spending all the money because there's always that kind of

bias that we've bought this supplement, it must be doing something. And do any of us ever really know if it's shortened the duration or made the symptoms better, because you would probably get better anyway over the course of a few days if it's, you know, a regular winter virus. You can find evidence for a lot of things. So elderberry, it's got antiviral compounds in it. And there's been studies done looking at that. Also contains vitamin C. Echinacea is quite highly studied. The challenge there is that there's many different types of the plant and different bits of the plant.

And so it's hard to get a consensus on which extract from which specific type is the one that's going to give you the best effect. And again, the science, we're not talking about huge meta-analyses where we're really have that convincing robust data. It's going to be a mixture of small studies and things done on cell culture rather than in large populations of humans. You know, other things like garlic, you know, we know that there's compounds in garlic that are really good for fighting off infections. But whether that's going to move the needle when you get those symptoms and whether you want to be chewing up raw garlic or you just want to be having something really nourishing and delicious.

I'd love to switch on then to, okay, let's say you're thinking about this and you'd like to be more healthy, have more quality years and a better quality over the next year rather than just like, hey, I need to do this one thing. And I know you discussed this in your latest book about Blueprint for Strong Immunity. And so I wanted to really touch into that. And I think the three areas I'd love to cover to get to like really practical advice for people listening. And I think you talk about nutrition, you talk about stress, and you talk about sleep. And I just love to understand like, what can you do where you feel there is really strong evidence that is really going to make a difference to this

immune system that I think you've done a brilliant cell that like we really need to look after for the long run if you want to stay healthy. Yeah, I think have that long game in your mind. You know, we live on average to 80 years old, but our health span is 60 years old and that's a delta of 20 years. And it's really emerging that the immune system is the key element to closing that delta. What you're saying is that you might only have 60 sort of quality years and you're saying you get it 20 years when you're feeling quite sick and you're saying the immune system you think is the most important thing for trying to make that a shorter period of time.

Yeah, exactly. And the things that are going to help that are also the things that are going to help you get through winter in terms of the sort of more short term feeling well and less downtime. And to me, the biggest piece of advice I can give to anyone in terms of diet is to follow a really anti-inflammatory diet pattern and stop hyper-focusing on superfoods. If you've eaten five or six superfoods on repeat, that's not going to be as beneficial as a really diverse dietary pattern that's anti-inflammatory. I often reference the Mediterranean diet only because it's the one that's perhaps the most studied and has the largest volume of evidence behind it, but it's bringing in all those

elements. So a variety of fruit and veg using really good fats like olive oil, lean protein, oily fish and fiber. So you know we've spoken about the gut microbes, but making sure those gut bugs are fed and happy right from the outset and then across the life course, because that's not only going to be supporting your immune system, it's going to be minimizing that unwanted inflammation that's going to be sort of taking energy away from, you know, your ability to fight infections. It's going to be reducing the driving of those hallmarks of aging. It's really, really important, I think, that the overall pattern of your diet is considered

rather than like, you know, we want to think of one or two superfoods, one or two supplements that we must take. And Jenny, can I ask you a question about that? So I follow, you know, the guidance I get from Zoe in my app every day and there'll be a lot of people listening who are members. And one of the things that has been most surprising to me, and I think was quite surprising to my co-foundant, Inspector and a lot of the other scientists,

is the health outcomes we're focused on were a lot about improving long-term health. But one of the things that's most surprising, actually, when we look at the results from the random clinical trials, is how many people feel much better very rapidly after just a few weeks. And one of the avenues that the scientists are sort of investigating is this idea that it's sort of the microbiome affecting the immune system that could be affecting how you feel.

Yeah. I mean, is that what's going on? What do you think? There's a really strong hypothesis there. One area that I used to work in was the gut barrier permeability. So how leaky and permeable the gut barrier is, and that happens. There's a natural physiological response every time you eat that you experience a certain amount of leakiness, and that's normal and natural and it's part of the digestive process. But when you create any sort of leakiness in that barrier, you're going to get bits of whatever is on the inside of your gut, so microbes and bits of microbes

and whatever else leaking into the body. And as soon as they're in the wrong place, they become a problem for the body. And when there's a problem for the body, the immune system is going to be alerted and it's going to turn on inflammation. So you get this post-prandial inflammatory response, which in a healthy individual, when it's happening in a really normal physiological way, is completely fine. But when we have a gut barrier that's not really robust, because perhaps the gut microbes are a bit out of whack because of poor diet or medications, that barrier is already going to have more leakiness than it would normally and the inflammation is

going to be increased and that burden of inflammation, if you think about across the life course, is going to have an effect on all the things that drive aging. And I think this is what we have to think about when we're looking at that sort of long term health picture. And do we understand, because I started leading with this other question around like how it makes you feel, like the mood and energy. Is that back to the way this immune system can have this? You know, you described about illness, is that linked or is this something completely different?

It's completely linked because inflammatory molecules that are being produced, as we spoke about before with the sickness behaviors, are going into your brain and they're acting on your brain and they're making changes in how you feel. And we even know now that there's a subset of people with mental health conditions that respond to anti-inflammatory interventions because it's like a form of sickness behaviors. So the response that we have when we have the flu that's meant to keep us lying on the sofa recovering is happening at a sort of low grade level and making people feel depressed and have poor mental health. When I'm sick, I feel low. Like it definitely affects my mood. I very rapidly am like,

I'm going to be sick forever. I'm never going to feel good. I just feel bad about everything in the world. Like, that's a real thing that like my immune system is doing to me. It's not just again, if I just had a better stiff upper lip like my, you know, my parents, my grandparents, I would... I mean, there might be some people who can really like dig deep and push through that, but it is a real physiological response driven by your immune system, communicating with your brain to adapt your behaviors.

And so this is an example of how it really can be true that the food you eat can genuinely change your mood and why some of the terrible ultra processed food we might be making us feel bad, but also how if you could shift that diet, which I guess is what we're trying to do with Zoe membership and with this podcast, you can see the explanation for why we see this shift in mood quite fast. Exactly, yeah. I'm particularly going to say that like everything to do with this, both immune system and microbiome, it's understudied and there's a lot to understand, yes? Yes, yeah, we've obviously simplified it down and there's obviously the gut brain access

where what the gut bugs are producing directly are going to be affecting the nervous system that route as well and there's going to be multiple pathways at play. But this link with unwanted inflammation being triggered is really having that impact on the brain. It's affecting our behavior. And it's also just that collateral damage, you know, our body's having to do the repair on that all the time. So we want to minimize that as much as possible.

We want to make sure that gut barrier is really robust. And the only way we can do that is by putting the right substrates in for those gut bugs to break down and produce things like butyrate, which is a direct fuel source for the gut barrier to fortify it and make sure it stays with its integrity. And if we're not putting the right fuel in, that mechanism can't happen. So you're going to compromise the gut barrier. And we now see links between this happening in the gut and autoimmune diseases. So things like rheumatoid arthritis where the

immune system's attacking the joint. We can see that by fixing the gut and improving the gut, we get an improvement in symptoms because what's happening in the gut isn't obviously staying there, it's able to, you know, transmit around the body. Do you know someone who's always complaining about getting sick? Could they benefit from learning more about their immune system and what they can do to make it better? If so, why not go ahead and share this episode with them right now? You'll empower them with the latest scientific advice and I'm sure they'll thank you. So you're saying that by changing what I eat and changing what's going on my gut and my gut microbes

that actually then affects my immune system that affects my arthritis in my knee. It can do, yeah. It does seem mad. I mean, you're used to it, but it's like I can eat something, just food, right? We're not doing magic and that can actually reduce my arthritis. Yeah, by working at this gut barrier interface, by promoting immune regulation, these T regulatory cells and by also stopping the microbes in the gut from being able to get into the body where they could travel around, cause inflammation

in areas like the joints. That is amazing. There's a lot of anecdotal stories about that actually from members and obviously Zoe is a wellness product, so it's not for treating any disease, but it's really interesting. That is one of the things that I've seen people just come up to me and talk about and I have, prior to this conversation, been like, I don't know. It's amazing to hear this, the way that the immune system is sort of linking these very different parts of the body. I would like to talk about stress, which you mentioned already, because you told this amazing

story about how you ended up with pneumonia. What can you do that could mean that you actually have an impact on your immune system by somehow reducing your stress? Is that possible? Yeah, this is probably the one I find most tricky from a very personal level, because, you know, there's a lot of different stress reducing techniques, but often these are kind of adding another layer to the life load. So I would say everybody needs to acknowledge the importance of stress

as having this impact on your physical health. Don't think of it as something that's in your head and start to develop an awareness of stress and how it might be impacting your health. Often it's the last thing we come to. We'll audit other areas of our life. We'll audit our diet, our sleep, our exercise. And sometimes actually wellness becomes a stress because people are trying to do things perfectly. I speak to a lot of people who see advice online and they can't quite apply it to their own life because perhaps it's being a bit misdirected and that too becomes a stress. So I think it's really like remembering to put things in context.

And I like to break it down and think of, you have to have some in the moment stress tools. So if you have a really difficult meeting at work or a difficult phone call, what can you do in the moment? And for me, it's things like getting outside, like widening the gaze. So we spend a lot of time hyper-focused

and because our eyes are part of our brain, when we change the gaze, it's giving signal to the brain that you're more relaxed when you have this broad view on the horizon rather than the laser focused looking at a screen. You're literally saying like put the phone away, walk into the garden and that actually can affect your stress?

Yeah, it can affect your stress. I mean, we're talking like little minute things, but it's all going to add up. There's not just one lever that we're going to pull. So we've got in the moment things altering your breathing. So when you are inhaling, your diaphragm is moving down, your heart has a lot of space, the blood flow is going to go faster, this is going to give a signal to your brain that you have to slow the heart rate down and then you exhale and so you have this thing called the respiratory sinus arrhythmia. So it's a constant interaction between the heart

and these sort of mechanoreceptors telling your brain when you need to speed up and slow down the heart rate. And Jenner, you're a very serious scientist. I just want to check, you are saying genuinely that changing your breathing could have an effect on your stress that could genuinely have an impact on sort of your immune system. This is not just completely crazy woo woo, like that's actually real? It does sound woo woo, but when you think about the biomechanics of it, you know, when we inhale and exhale, we're sort of making more and less space inside our chest cavity. So the heart is going to pick up on that and that's going to give the heart more or less

space. So the brain is going to tell the blood flow to speed up or slow down. And this is tapping into the two arms of of what we call the autonomic nervous system. So that's your fight or flight response, which is kind of the stress arm, and then the rest and digest arm, which is the more kind of relaxing, less stressed part of the nervous system. So the counterbalance to stress and elongating the exhale. So just taking a normal inhale and then making sure that exhale is slowed down through the nose, this is going to really tap into that rest and digest parasympathetic part of the nervous system.

So it's helping to bring a bit of calm back to the whole nervous system and help take the edge off the stress. There really are real clinical trials out there looking at reducing stress and those really do show an impact on the immune system. So this isn't just theoretical. This isn't just theoretical. Yeah. And we've spoken about the in the moment ones, like just going outside, changing the gaze,

you know, Elon getting the exhale. But I also think that we need some tools that are kind of a buffer for when it might happen. And, you know, there's lots of studies on, you know, the long term meditators and people who practice different kinds of mindfulness. And these are the things that I think we need to not wait until we're stressed before we try. They're kind of the ones we should be trying to sprinkle through our week, because they'll make us more robust if the stress comes. I'd like to finish with the last thing that actually you picked up on, right,

which is around sleep. And you said that in your own case, I think again, when you're describing pneumonia, you're like, well, I don't know how much was the stress of small twins and how much was the lack of sleep. What does sleep do to our immune system? Again, I love to look at things through the lens of evolution. And if you think during the day, you know, you go out of your house, you're interacting

with people, you're exposed to germs, you're exposed to things that could damage you. So your immune system has a specific state during the daytime, because that's when the risk is highest. And then when you go to sleep, you know, you're sleeping in, you would hope, a safe, closed environment, so there's much less risk of injury, of infection, of things happening. So it kind of switches gears and performs kind of more housekeeping duties. So there's this real kind of circadian change in your immune system. And it's again, dialing into your brain.

So it's a communication with your brain because when you're out and about and you see daylight, the sort of lots of genetic switches that will click and say, right, it's daytime, we need this kind of immune activity. And then again, when it gets to darkness and we start to sleep, that again helps relay the signal to the immune system that we have to change and prepare for sleep. So that period when we're asleep is really important for this sort of housekeeping to happen. And earlier in our conversation, I mentioned the natural killer cells as being these kind of first line responders for viruses. And we know that they're very sensitive to sleep. So when we start to reduce the amount of sleep we get, we impair their ability to do their

job. And so you can imagine as the sleep goes down, the risk of getting a cold or flu goes up. So the less sleep you're getting and the more you hop on the tube to work or go out and you're exposed to viruses, the less sleep you've got, the higher the risk that will actually end up a full-blown infection. I love this. I need to sleep to let my natural born killers free to kill my own cells at night. This is like, it's slightly freaky.

And final question just triggered by that, just, and it's probably crazy. You talked about how sleep is really important that we need this sort of housekeeping time for our immune system, that like it knows it's certain times of day to do something different. And that's come up quite a few times on the podcast, but particularly talking about eating and the fact that there's a lot of evidence now that it's really important to have a long period of time when you're resting your gut, to allow your gut to go through all sorts of housekeeping. Has anyone studied at all whether there's any link to do with sort of time restricted eating or you know midnight snacking having an impact on your immune system and these things are linked or are they just two different examples of why it's important that we have

a day and a night? I don't know that it's been directly looked at, but the body loves routine. It sort of takes the whole weight off when there's an expectation of when things will happen. So there's lots of science about consistent bedtimes, as you said, consistent eating times and having that sort of period of rest between meals because it's, it conserves energy because then you know when to anticipate what to do when.

So, and again, if we think about that gut barrier and the potential for inflammation when we're eating, you know, if we have really erratic or sort of multiple meal times, then that post-eating inflammation is going to be extended. And we want to really time box that into specific parts of the day so that our immune system can deal with that. And again, we haven't touched on it yet, but there's a new field of immunology called immunometabolism. And that's because our immune system is interlinked with our metabolism because immune system is very energetically costly. So it needs to be talking to our metabolism to get the energy to fuel that.

And you touched on things like time-restricted eating, eating late at night and how that affects our metabolism. So you would imagine that there would be a natural downstream impact on the immune system if our metabolism is being affected by erratic eating times, eating late in the day or during the night. And we do see that the health of shift workers is affected by that. I don't know if anyone's ever looked at direct markers of their immune system, but I'm certainly going to look in the literature later. Well, I mean, as you know, Zoe, we like to do really large-scale scientific studies. So can I tempt you maybe to think about how we might do something

about time-restricted eating and impact on the immune system? You don't know what a geek I am. I'm like, my brain has already started. I'll follow up with Dr. Sarah very afterwards and she'll probably already, as soon as she listens, be like, that's fascinating. But I am really intrigued by the way in which you're describing how much of the immune system is managing these bacteria. And we know, I think from a lot of scientists working with us, that what's going on inside the microbiome is actually changing sort of during the period when you're not eating. And so there's clearly something important that's going on there. But you're saying that the puzzle pieces haven't all been put together.

Yeah, but I think there's a picture I can see that is worthwhile exploring. That's very exciting. I think for anyone listening, what you see here again is just how much the science around all these areas is still new. And so when you talk to someone who's at the cutting edge, and we're very lucky to do that, you're also often saying these are the things that we don't understand yet. Yeah, exactly. Which I always think is the marker of a scientist you should trust.

Can I try and do a quick summary of at least some of the things we covered a lot? Sure. My starting point is you said this one thing, we live in a germy world, so we can't be invincible. We're going to get these things and actually you don't want your immune system to be like super boosted, which in the long run, that could be really harmful. And the reality is actually our immune system is on too much. And this is what's leading to, you know, things like, you know, more risk of diabetes, but it could always can impact your risk of cancer. So actually, we want to sort of calm immune system. And the immune system is having like a much bigger impact than we realize. So, you example, if I am sick, it is true that that immune system is sending chemicals

to my brain that are actually going to make me feel bad, like lower my mood, make me tired. And we should, you're sort of suggesting don't ignore it all, take all the pills to stop it going away. Like this is actually sort of signaling to you how to respond. The other thing I think that's amazing you talked about is that the bulk of our immune system is actually where our microbes are and that we now know that the microbiome is really important for sort of fine tuning you described the immune system, that that's somehow something critical that's happening when we're in our first few years of our life, that somehow

these microbes are even training us, which is really weird, and that basically a bunch of stuff has been going wrong over the last, you know, 50 or 60 years, you know, whether it's antibiotics, changing food, ultra processed food, all the rest of it. So we see this really big rise in allergies and autoimmune, but it also means that today you said that our microbiome should be producing a whole set of chemicals that are sort of helping the peacekeeping part of our immune system. And I think you mentioned this thing, butyrate. Butyrate, yeah, it's one example. As an example, but basically, like our microbiome should be like arming the peacekeepers, and

that's not happening because we're not eating the right food and we don't all have the right good bugs. And therefore, somehow our immune system, one of the ways in which our immune system is out of balance like we've got all the guys out there with the guns but we've got none of the sort of calm inside of this that is why the food you eat is going to be much more important than popping a particular superfood or a vitamin C but then I think you talked about two other really interesting things that I think a lot of us felt maybe weren't real and you're saying this is real as a scientist who studies this, which is stress has a direct impact on your immune system. This isn't made up, it's not just in your head, like you can measure it in a lab, it's

physical. It's also really hard to reduce is what you're saying, which made me feel better. But there is real clinical evidence that things that sound crazy, like breathing exercises, could actually reduce your stress. Putting the phone outside and just going outside. And if you can reduce your stress, it will actually improve the function of your immune system. That's important. And that sleep, which again, I remember when I was young, it's like, you know, sleep is for wimps. Actually, sleep is really important. Like, if you cut back your sleep, you're going to worsen your immune system. Because I've got these natural born killers in every part of my body, but they only come

out when I go to sleep. This combination of things can really have an impact on this immune system. And that immune system is really affecting every part of my health. Exactly. It really is the kind of the arbiter of our health across the life course. And, and it's a very complicated system. I think any immunologist would put their hands up and admit that we really haven't got it all figured out yet, but there's so many inputs that are going

into it and we do have some control over those inputs, so it's trying to think about all the little things that we can do and thinking of that compounding over time, rather than just like, oh, I've got sick, what can I take? Just like the little things we do every day, I think add up. Amazing. I really enjoyed that. I hope we can get you to come back in the future because I think there's lots of areas here we haven't touched. And we will follow up on that new research.

Oh, thank you. It's been a pleasure. It's been wonderful. Thank you, Jenna. I really enjoyed having Jenna on that new research. Oh, thank you. It's been a pleasure. Been wonderful. Thank you, Jenna. I really enjoyed having Jenna on the podcast today. I learned a lot of new things and I hope that you did as well. My biggest takeaway is that there's never a quick fix for solving your health.

So taking that vitamin C when you're sick isn't what's going to matter. It's about actually having gradual and sustainable changes over time that just improves the state of your immune system, the state of your health permanently. And if you listen to the show regularly, then you probably already believe that and you probably already believe that you can transform your health with food. But now there is only so much you can learn from general advice on a weekly podcast. If you want to feel much better and be on track for more healthy years, you need something more. And that's why each day more than a hundred thousand people rely on Zoey membership, our personalized nutrition program to make smarter food choices,

to feel better in weeks and be on track for more healthy years. So how does Zoey membership work? First, your at-home tests allow you to understand your body's responses to food and the good and bad microbes in your gut. Then Zoey's app uses your test results to create your personalized program, helping you build life-changing nutrition habits step by step. Your program includes recipes, meal plans, food scanning, and simple scores out of 100 for any meal. And regularly retesting your gut health lets you track your progress. I rely on Zoe's advice every day, and truly it has transformed how I feel.

So will you give Zoe a try? The first step is easy. Take our free quiz to find out what Zoe membership could do for you. Simply go to Zoe.comcom, whereas a podcast listener, you can get 10% off using the code podcast. As always, I'm your host, Jonathan Wolff. Zoey Science and Nutrition is produced by Seb Masters, Julie Pinero, Sam Durham, and Richard Willem.

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