4 immunity tips for healthy ageing

Over the last two years, there’s been a rise in “immune-boosting” foods, supplements and trends. Immunologist Dr. Jenna Macciochi believes the immune system doesn’t need ‘boosting’. Instead, we should focus on ‘balancing’. 

Dr. Jenna Macciochi is an author, health coach, and Senior Lecturer in Immunology at The University of Sussex. Her work looks at nutrition, mind-body practices, lifestyle medicine, and personalized approaches to improve immune health. 

Have feedback or a topic you'd like us to cover? Let us know here.

Episode transcripts are available here.

Transcript

Jonathan Wolf: In the last two years, there's been a surge in Google searches containing two words; immune boost. And what's followed has been a wave of brand new products, detoxes, supplements, and 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? Dr. Jenna Macciochi joins us today to separate fad from fiction. 

Jenna is a senior lecturer in immunology at the University of Sussex, and author of The Science of Staying 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. 

Dr. Jenna Macciochi: Thanks for having me. It's great to be here. 

Jonathan Wolf: 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, or if you absolutely have to, you can give us a one sentence answer.

Are you willing to give it a go? 

Dr. Jenna Macciochi: Yep, let's go. 

Jonathan Wolf: All right. Can I improve my immune system without taking drugs? 

Dr. Jenna Macciochi: Yes. 

Jonathan Wolf: Is the immune system mainly to fight off illness? 

Dr. Jenna Macciochi: No. 

Jonathan Wolf: Should you try to boost your immune system? 

Dr. Jenna Macciochi: No. 

Jonathan Wolf: Will taking vitamin C supplements reduce my chance of getting a cold? 

Dr. Jenna Macciochi: No. 

Jonathan Wolf: Can my emotions make me ill?

Dr. Jenna Macciochi: Yes. 

Jonathan Wolf: And last one, you can have a whole sentence. What's the biggest misconception about the immune system? 

Dr. Jenna Macciochi: I'd say that if you get sick, we're going into winter, seasonal viruses are around, if you get sick, it means you've got a rubbish immune system. 

Jonathan Wolf: Well, you know, that's brilliant, because that is 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 mum was always the person who would pick us up from school, she was also looking after us.

And I remember every few months, basically, my mom would just sort of collapse at the end of the day or when she came back from work, 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.

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 five days until I feel like I probably got better. 

So I'm just basically really curious about have I just inherited my mother's terrible immune system. How much of this is about the stress that I know that I put myself under and that I feel.

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.

Dr. Jenna Macciochi: 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, she's getting more exposure to kids. Kids are little germ factories because the sort of basic hygiene is sometimes a work in progress. 

Join the community

Be the first to know about ZOE’s breakthrough research, content from the world’s leading scientists, and more.

Jonathan Wolf: That is for sure. 

Dr. Jenna Macciochi: So, that's a 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 mom and dad.

Jonathan Wolf: 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. Actually, I don't understand what the immune system is at all. It's one of those words that I use, but I don't understand it. What is it? 

Dr. Jenna Macciochi: It's hard to grasp. And we talk about it as one thing.

If I asked you to say 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. That's because it's everywhere. 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, 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 maintain 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, 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 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.

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. 

Jonathan Wolf: It's a beautiful picture, I'm starting to think about all that's 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? 

Dr. Jenna Macciochi: 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.

Jonathan Wolf: 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 about what it does, and how it works? 

Dr. Jenna Macciochi: It's hard to conceptualize 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 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 are 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.

Jonathan Wolf: Is it just for dealing with colds and flu and nasty bacteria or is there more to it with the immune system? 

Dr. Jenna Macciochi: 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 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, 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 deal with what's there. 

So, you know, you're unfortunate enough to inhale a whole dose of some, you know, 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.

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 these 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. 

Jonathan Wolf: 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.

Dr. Jenna Macciochi: Yes. 

Jonathan Wolf: Very sort of Game of Thrones. 

Dr. Jenna Macciochi: 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. 

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. 

Jonathan Wolf: That's amazing. So we're sort of killing our own body, every time I have a cold. 

Dr. Jenna Macciochi: If you're traveling on the tube 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. 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. 

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 going to spread that infection, and B, you're consuming energy that your body could instead put into getting well again.

I think this herein lies the problem in that 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.

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 you know 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. 

Jonathan Wolf: 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.

Dr. Jenna Macciochi: 100%. And also because it stops you spreading the infection. So there may be something that that's dialed in through our evolution as well. 

Jonathan Wolf: I remember, again, as a child, it's like, oh well you can't have the same thing that I have, because 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, how much, is that the virus, is that my own immune system? 

And why is it, I guess, coming back to my mum and dad, that she might be flat on the bed for 24 hours, and my dad must be exposed to it, I guess, if they're in the same room, and seems to sail through?

[00:14:18] Dr. Jenna Macciochi: 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 everything from your health status, 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, 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 mum coping with 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. 

Jonathan Wolf: That's terrible. 

Dr. Jenna Macciochi: Everyone else got better from the cold, but I didn't.

Jonathan Wolf: Is your explanation of that, that you didn’t rest or that your immune system was more compromised or what?

Dr. Jenna Macciochi: I mean I think it's a combination and obviously this is an n=1 experiment.

Jonathan Wolf: Which is science speak for saying it wasn't a full trial. 

Dr. Jenna Macciochi: Yeah, it was an observation case study of myself. 

Jonathan Wolf: We are on a podcast so the floor is yours.

Dr. Jenna Macciochi: I can declare that upfront. But if I zoom out and remember that time in my life, when 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. 

I didn't rest, because as a parent and juggling work, there isn't always that time, and I do believe that that was important in what happened next. Because the lack of sleep, the stress that's sort of an ongoing stress and not resting, not listening to those sickness behaviors. 

Jonathan Wolf: And Jen, how would the lack of sleep and the stress affect your immune system? Because again, I can definitely feel like my grandparents would've been like, that's all in your mind, just get on with it. So that would all just be being sorry for yourself. 

Is there actually real science that that actually has an effect on your immune system? 

Dr. Jenna Macciochi: Yeah, there is real science and this is where it starts to get complicated because 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 sort of 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're going to 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 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. 

Jonathan Wolf: 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 protecting you from a virus, but it could have an impact on your long-term health.

Is that right? 

[00:18:42] Dr. Jenna Macciochi: 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 thing that we call the immune system.

But it does so many other jobs. 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, your tissue is going to you 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 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. 

Jonathan Wolf: Which is amazing.

Dr. Jenna Macciochi: It's amazing. Yeah. And that's what has birthed 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, yeah, it's a really amazing bit of science that is going to change how we deal with cancer. 

Jonathan Wolf: 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?

Dr. Jenna Macciochi: I think that's a hard question to study and a hard question to definitively answer, but we do have clues from the literature, people who suffer with certain conditions have higher risks of cancer. 

So there is a link there, but I think there's 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.

Jonathan Wolf: And then I'd love to ask you a bit about the microbiome because my co-founder, Professor Tim Spector has discussed with me and on this podcast that we now understand that an important part of what the immune system is doing is actually managing all of these microbes in our gut.

Which in this case are not bad for us, they're not toxic, they're somehow an essential part of how we're meant to be.

Dr. Jenna Macciochi: Yes. 

Jonathan Wolf: Is that right? And what's going on and how well do we understand this? Because I know that everything around the microbiome is quite new within science. 

Dr. Jenna Macciochi: 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 other 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. So there's a crosstalk that goes on all the time. 

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. 

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, clears up the damage and keeps the homeostasis within the body. And this is where this relationship with the microbiome was so important. 

The microbiome are eating what we eat and they're breaking that down and their 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 T regs. 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. 

Jonathan Wolf: That's amazing. And one of the things we know is that we're eating diets that are very different from the diets we ever used to eat. Very little plants, 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 in the past, those bacteria would have been creating this, 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 nature intended.

Dr. Jenna Macciochi: Yes. It often feels like this system has been designed so 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, 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 explores a 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.

When we look back through history, you can see that there is a strong correlation with the use of antibiotics from the 1950s. Then we started having more convenience foods, ultra-processed foods, dietary fiber 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. 

Jonathan Wolf: 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. 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 when you said immune boosting is bad. Why isn't this a great thing?

Dr. Jenna Macciochi: 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. 

I think that we kind of think about. all the wrong way. We want to have something that will make us invincible to germs. And we live in this really germy world 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 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, and 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 make 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. We want to have the balance. We want to have response 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 quiet immune cells that are not spitting out inflammation.

So the boosting part just doesn't make sense. 

Jonathan Wolf: Your body is jumping on everything. When actually it could have just let it slide by and instead it's triggering all of these 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 more on.

Dr. Jenna Macciochi: Exactly, because I think there's so many things that trigger unnecessary inflammation. Stress, pro diet, lack of exercise, pollution, the list is endless. And actually we want to be turning that off as much as possible. 

So boosting, which bit are you boosting for how long, for how much, because the immune system is this huge constellation of a million different types of cells and, and molecules.

So to shrink it down to an on-off switch, to me, 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 because people are scared. You don't want to get sick. You want to get through winter without having to take time off work.

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. 

Jonathan Wolf: 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?

Dr. Jenna Macciochi: 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 perhaps you do a lot of running or a lot of sports, and you're under a lot of stress, 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 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 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. 

Jonathan Wolf: 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. 

Dr. Jenna Macciochi: There is evidence there, but to me, I think the rest is probably a better way to, that's where I'd put my money. Have an afternoon on the sofa, don't go to work, get some proper rest, eat some really nourishing food, like delicious soup that's packed with 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 bioflavonoids 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 science, you could take a gram of vitamin C and spread it throughout the day with a supplement. 

Jonathan Wolf: 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 being able to improve the overall diet and the things you were talking about? 

Dr. Jenna Macciochi: 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 are 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 what we should be doing every day, not just waiting until 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 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 are 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 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, 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.

Jonathan Wolf: 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 a blueprint for strong immunity.

And so I wanted to really touch on that. And I think there are three areas I'd love to cover to get to really practical advice for people listening. I think you talk about nutrition, you talk about stress and you talk about sleep.

I just love to understand 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 sell that we really need to look after for the long run if you want to stay healthy. 

Dr. Jenna Macciochi: 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.

Jonathan Wolf: What you're saying is that you might only have 60 quality years and you're saying you're going to 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. 

Dr. Jenna Macciochi: 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 more short-term feeling well and less down time.

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 eat 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, 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 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 we want to think of one or two superfoods, one or two supplements that we must take.

Jonathan Wolf: And Jenna, can I ask you a question about that? So I follow 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-founder, Tim Spector, 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. 

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.

I mean, is that what's going on? What do you think? 

Dr. Jenna Macciochi: I 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 as 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 gonna get bits of whatever's on the inside of your guts, 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 postprandial 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. The inflammation is going to be increased and that burden of inflammation, if you think about it 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. 

Jonathan Wolf: I started leading with this other question around how it makes you feel, the mood and energy. Is that back to the way this immune system can have this for, you described about illness, is that linked or is this something completely different?

Dr. Jenna Macciochi: 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.  

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 behavior.

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. 

Jonathan Wolf: When I'm sick, I feel low. It definitely affects my mood. I very rapidly, I'm like, I'm gonna be sick forever, I'm never gonna feel good. I just feel bad about everything in the world.

That's a real thing that my immune system is doing to me. It's not just again, if I just had a better stiff upper lip, my grandparents, I would…

Dr. Jenna Macciochi: I mean, it might be some people who can really 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.

Jonathan Wolf: 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 eat 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 could see the explanation for why we see this shift in mood quite fast.

Dr. Jenna Macciochi: Exactly. 

Jonathan Wolf: I'm particularly going to say that everything to do with this, both the immune system and microbiome, It's understudied and there's a lot to understand. 

Dr. Jenna Macciochi: Yes, 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, 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.

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 joints, 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 transmit around the body.

Jonathan Wolf: 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? 

Dr. Jenna Macciochi: It can do, yeah. 

Jonathan Wolf: It does seem mad. I mean, you're used to it, but I can eat something, just food, right, and that can actually reduce my arthritis symptoms.

Dr. Jenna Macciochi: 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. 

Jonathan Wolf: 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 would actually have an impact on your immune system by somehow reducing your stress? Is that possible? 

Dr. Jenna Macciochi: Yeah, this is probably the one I find most tricky from a very personal level because 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 been a bit misdirected and that too becomes a stress. 

So I think it's really 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, 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 a 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.

Jonathan Wolf: So you're literally saying put the phone away, walk into the garden, and that actually can affect your stress? 

Dr. Jenna Macciochi: Yeah, it can affect your stress. I mean, we're talking little minute things, but it's all gonna add up. There's not just one lever that we're gonna pull. 

So we've got in-the-moment things, altering your breathing, so when you are inhaling, your diaphragm's 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 mechanoreceptors telling your brain when you need to speed up and slow down the heart rate.

Jonathan Wolf: And Jenna, 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 your immune system. Yeah. This is not just completely crazy, woo woo, that's actually real? 

Dr. Jenna Macciochi: It does sound woo woo, but when you think about the biomechanics of it, 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 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.

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. 

Jonathan Wolf: 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. 

Dr. Jenna Macciochi: 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, elongating 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 are lots of studies on the long-term meditators and people who practice different kinds of mindfulness.

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. 

Jonathan Wolf: I'd like to finish with the last thing that you picked up on, 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. 

Dr. Jenna Macciochi: Yeah. 

Jonathan Wolf: What does sleep do to our immune system? 

Dr. Jenna Macciochi: Again, I love to look at things through the lens of evolution. And if you think during the day, 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'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, it's a communication with your brain because when you're out and about and you see daylight, there's sort of lots of genetic switches that'll 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. 

Earlier in our conversation, I mentioned the natural killer cells as being these kind of first-line responders for viruses. 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 about, 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. 

Jonathan Wolf: I love this. I need to sleep to let my natural-born killers free to kill my own cells at night. This is slightly freaky. 

And the final question, just triggered by that, 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 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 time-restricted eating or 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?

Dr. Jenna Macciochi: 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 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. If we have really erratic or sort of multiple mealtimes, then that post-eating inflammation is going to be extended. And we want to really timebox that into specific parts of the day so that our immune system can deal with that.

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 the 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.

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. 

Jonathan Wolf: Well I mean as you know at 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?

Dr. Jenna Macciochi: You don't know what a geek I am. My brain is already starting to…

Jonathan Wolf: I'll follow up with Dr. Sarah very afterward and she'll probably already, as soon as she listens, she'll 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. We know from, I think a lot of actually 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.

Dr. Jenna Macciochi: But I think there's a picture I can see that is worthwhile exploring. 

Jonathan Wolf: 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 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. I mean, 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 super boosted, which in the long run, that could be really harmful.

The reality is actually our immune system is on too much, and this is what's leading to, you know, things like more risk of diabetes, but it could always can impact your risk of cancer.

So actually we want a calm immune system and the immune system is having a much bigger impact than we realized. So for 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, lower my mood, and make me tired. And you're sort of suggesting don't ignore it all, take all the pills to stop it going away, 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. That we now know that the microbiome is really important for fine tuning, you described, the immune system. 

That 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 50 or 60 years, whether it's antibiotics, change in 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 helping the peacekeeping part of our immune system. you mentioned this thing, butyrate. 

Dr. Jenna Macciochi: Butyrate. Yeah, it's one example.

Jonathan Wolf: As an example. But basically our microbiome should be 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 it's one of the ways in which our immune system is out of balance. 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 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. 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, 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 was like, sleep is for wimps. Actually, sleep is really important. 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. 

Dr. Jenna Macciochi: Exactly. It really is the kind of the arbiter of our health across the life course 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 the little things we do every day, I think add up. 

Jonathan Wolf: 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. 

Dr. Jenna Macciochi: Oh, thank you. It's been a pleasure. 

Jonathan Wolf: 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 100,000 people rely on ZOE 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 ZOE 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 ZOE'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.com where as a podcast listener, you can get 10% off using the code PODCAST.

As always, I'm your host, Jonathan Wolf. ZOE Science and Nutrition is produced by Seb Masters, Julie Pinero, Sam Durham, and Richard Willan. The ZOE Science and Nutrition podcast is not medical advice. And if you have any medical concerns, please consult your doctor. See you next time.