ZOE Science & Nutrition - Is your gut making hay fever, seasonal allergies, eczema and food intolerances worse? Here are 5 ways to fight back | Prof. Adam Fox

Starting point is 00:00:00 Welcome to Zoe Science and Nutrition, where world-leading scientists explain how their research can improve your health. In a cafe downtown, a customer notices something changing. It's just a tingle on the lips. It feels harmless, but within minutes, the situation has become life-threatening. Meanwhile, in a restaurant a few doors down, a diner feels queasy and bloated. Their eyes dart around looking for the quickest way to the toilet. Food intolerances and allergies were once rare, but within a single generation, they've exploded. Until 20 years ago, most of us had never heard the word gluten. Today, gluten-free products have their own shelf at the grocery store.

Starting point is 00:00:51 Dairy food options are also widely available. In the past, these allergies were vanishingly rare, but now conditions like peanut allergy and seasonal allergies like hay fever have surged, reshaping what we can eat on a plane. or put on our kids sandwiches. Today, restaurants ask for allergies and nut-free zones are increasingly common. What has driven this change? Cleaner homes, changing diets,

Starting point is 00:01:17 or something else entirely? In this episode, Adam Fox, professor at King's College London, one of the world's leading allergy researchers, helps us to unravel the science behind them. What's really happening inside our bodies? Why are some people more affected than others? And crucially, what can we do about it?

Starting point is 00:01:36 Adam, thank you so much for joining me today. Pleasure to be here. So we like to kick off our show here at Zoe with a rapid-fire Q&A with questions from our listeners. Are you up for that? Definitely. And we have some very strict rules. Okay. You can say yes or no, or if you have to, you can have a one-sentence answer.

Starting point is 00:01:58 Let's do it. Adam, are people born with food allergies? No. Can you develop a food allergy as an adult, even if you've eaten that food your entire life? Yes. Were our hunter-gatherer ancestors allergic to pollen? No. To most people who think they have a penicillin allergy really have one.

Starting point is 00:02:20 No. Are allergies and food intolerances the same thing? Definitely no. And finally, what's the most common misconception about allergies? I think it's that allergies are trivial because for some people they are actually life-defining. Now, my sense is that allergies are getting increasingly common. When I was young, I'd never even heard of peanut allergy. And now my daughter can't take a peanut butter sandwich to school. And I think intolerances are the same. So this is sort of a transformation in terms of the world we're in compared to the one when I was a child. That's my impression. But actually, have food allergies increased overall? And how common are they now in, you know, the US and the UK? It's a really, really good question. And you're absolutely right regarding your impression because when I was at school, 1980s, I was at school with 1,500 kids. And there was one child who had a peanut allergy. And everyone knew about it because it was such a strange thing that this child would have a terrible reaction if you went near a peanut. And it's desperately sad because that young man went on, he got a job in the Far East, spent some time in Hong Kong. And on his way home, he had a fatal anaphylaxis to peanut. Now, my son went to the same school that I did.

Starting point is 00:03:41 We still live in the same area. And he was 30 years below me. And I probably, by the time he left, knew about a quarter of his class professionally. As the local allergy doctor, I was seeing these kids. And there's a lot of them. And I knew for my son's friends when they were coming over to play that a number of them would present us with their epipens when they arrived. And, you know, you used to have delighted parents when they discovered that Ethan's dad was an allergy doctor because they could really relax a lot more. So clearly something significant

Starting point is 00:04:14 changed in terms of disease patterns over the course of those 30 years. And that's reflected in the data. If you gather a lot of studies together, we can sensibly estimate that around 5% of children in the UK, US, for example, will have a food allergy. Now, you can also look at patterns over time and there's nice data actually from the UK, from National Health Service primary care databases that show that between 1998 and 2018, so 20-year period, there was a troubling in the number of people presenting to emergency departments with severe allergic reactions. So this is a very significant increase, year-on-year, six or seven percent to get to those sorts of amounts. And if you dig in to, well, why is that happening?

Starting point is 00:05:03 adults having allergic reactions to penicillin, or is it teenagers with latex allergy? It's not. It's younger children with food allergy that's driving that increase. And if you then look at other robust data that looks at the general practice reporting of food allergy amongst patients, we can see that in the 10 years between 2008 and 2018, and then data sort of dropped off because of COVID that really impacted the ability to collect reliable data. There was a doubling of food allergy during that period reported. So we've seen really significant changes. And then if you just go back 100 or 200 years into Lancet papers,

Starting point is 00:05:42 it's pretty clear that if there was mention of allergy, it was pretty unusual. Whereas, of course, today it's not. The thing that springs into my mind is peanuts when I think about peanut allergy. And maybe that's partly because you can't take peanut butter to school. And so that focuses the mind. But how much of this is an allergy to peanuts within this food allergy? or is that just the thing that springs to my mind and I'm being a bit mean on the peanut? No, you're not.

Starting point is 00:06:06 There's a couple of reasons why peanuts seems to get all the headlines. So firstly, it is a really important allergen. About 1 in 50 kids in the UK, 2%, we think, have a peanut allergy. It's amongst a relatively select group of foods that do account for most food allergies. So milk allergy, egg allergy, peanuts, tree nuts, sesame, wheat, kiwi, sesame, a relatively small number of foods in the bigger scheme of things account for the overwhelming majority of food allergy that we see. But peanut has often been used as the modelling the search studies because it's serious, you don't grow out of it, unlike milk and egg allergy, which commonly you do. So it's been a real focus of academic attention, but then also

Starting point is 00:06:48 it is responsible for some of the fatal anaphylaxic reactions that happen. But interestingly, it's not the most common cause of fatal anaphylaxis, certainly not in younger children, because milk is the most common cause in younger children. Did you just say that the most common cause of like serious allergy is milk? The most common cause of fatal anaphylaxis, the most common cause of anaphylaxis in younger children is milk. It's not peanuts. Now, a couple of reasons. So firstly, milk allergy in younger children is much more common than peanut allergy, but most of it is outgrown.

Starting point is 00:07:23 So amongst an adult population, you're going to find more persistent allergy from childhood to things like peanuts and tree nuts and cessonets. me because you uncommonly grow out of those maybe 10, 20%. Whereas with milk allergy, 80% of children with milk allergy will outgrow it and won't be allergic in adulthood or later childhood. I want to come back to that, but we were just talking about peanuts. And I'm sort of curious. You said there has been this big rise. It is a really important part of the allergy.

Starting point is 00:07:52 Is this true everywhere around the globe? No. So what you become allergic to really does relate to what's being eaten in the household that you're brought up in. And you see this, it's fascinating. You see this in the very diverse populations that we see in a central London teaching hospital, so where I work, and you will notice slightly different patterns of disease amongst different communities. So for example, in India, chickpeas, lentils are much more common allergens than things like peanuts. And amongst British Asian families, if they've got a nut allergy, it's more commonly going to be something like

Starting point is 00:08:27 cashew, pistachio, walnut, than it is to be peanut. And that, just reflects what's being eaten in the household amongst Middle Eastern families. If you look at rates of allergy in Israel, for example, sesame is a really important allergen. And that's because a lot of families eat hummus. So where you go, what's being eaten will influence what you're likely to see causing allergies in children. I might have thought I'd be allergic to the things I've never been exposed to. But you're saying actually I'm allergic to the things that I grow up with. as we have developed a better understanding of how you become allergic in the first place, it sort of makes sense that it's going to be the things that you grew up with.

Starting point is 00:09:06 Not just anything, it's going to be the things that are particularly good at inducing allergic responses. And there's certain foods that seem to be very good at inducing allergic responses. And they're typically things that are sort of quite sticky and have proteins that, for sometimes reasons we don't really understand, are particularly good at upsetting our immune system. But a great example of that would be peanut. but another good example would be sesame. So often both of them are eaten in forms that are quite sticky.

Starting point is 00:09:32 So peanut butter, hummus, for example. And what I mean by sticky is they get around. So you're likely to find residue of that food, not just around your mouth, but on your hands, on surfaces. And because our understanding of how you become allergic has evolved and now we understand that it's all about early infancy, problems with your skin barrier, so the presence of exma,

Starting point is 00:09:53 and exposure through the skin barrier to those sticky, potentially allergenic proteins. So I guess what I'm trying to say is if you're a baby with eczema and you've got siblings or parents that have eaten hummus or peanut butter and they're kissing or touching that baby, and that baby's immune system through the disrupted skin barrier because of the eczema gets to see those proteins and doesn't know what they are because the infant has never eaten that food before, that's when you're at risk of developing allergy.

Starting point is 00:10:21 You're saying we tend to develop this when you're a very small child. Correct. And that what's happening is actually my immune system is getting exposed to, you know, this peanut or this sesame through something that sort of gets stuck onto the skin, like peanut butter or hummus, possibly through someone else in the family kissing me on the arm or my older brother whacking me, whatever it is. And then somehow it's getting in because the skin barrier hasn't blocked it out. And my immune system is like, hang on.

Starting point is 00:10:51 this is something bad, red alert. Yeah, let's develop an inappropriate immune response, because that's what allergy is, an inappropriate immune response to something that should be ignored. So it all comes down to where that immunological signal is received. Because if, as an infant, that child, exma or no exma, the first time they come across peanut or sesame eats it, then the part of their immune system that sees it is the gut immune system, which is primed to acknowledge that anything it sees in the gut is most likely food, so can be ignored, and there's no need to develop an immune response.

Starting point is 00:11:26 And so the next time you eat that food, no problem. Whereas your skin immune system is thinking very differently, because your skin is designed and expected to be covered by the skin barrier, which is meant to provide an impervious wall between itself and the outside world. And its immune system is ready that if anything gets past that impervious, So you've got to cut in your skin and germs or bugs get through, your immune system is there ready to kill whatever it is that it finds. And ideally adapt to recognise what those things are so it can kill it even more effectively next time round. But if what it's seeing are actually harmless things because your skin barrier isn't working properly, it's not an impervious wall, it's a leaky barrier.

Starting point is 00:12:08 Because genetically you don't have the glue that sticks your skin cells together, then there is a risk that your immune system will see things it's not designed to see and make, bad decisions because it doesn't have context. It doesn't know that that food protein that sat on your skin barrier is food because that infant has never eaten it before. Why is the skin not keeping these things out? For decades, we've been led to believe that the brain is completely separate from our body. We thought low mood was just chemicals and that cognitive decline was an inevitable part of aging. A roll of the dice we had no control over. But at Zoe, we know the science says otherwise, and the truth is far more revealing. There's growing evidence to suggest that our brain doesn't act alone. It's in a constant partnership with our gut. If you've been feeling

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Starting point is 00:13:40 your plate. Most people wait until they notice a decline to start caring about their life. brain. But longevity isn't luck. It's a choice you make before you need it. Don't leave your cognitive future to chance. Go to zoe.com slash brain health right now to claim your guide. That's zoe.com slash brain health or click the link in the show notes. Well, because there is skin barrier dysfunction, which is a fancy way of saying that your skin barrier isn't working as well as it should, you don't have to spend long in an allergy clinic, certainly when you're seeing younger children, for it to be really clear that there is a relationship between eczema and food allergies. So it's from the probably say 20% of children that we see who have eczema, it's from that

Starting point is 00:14:25 population that we see the overwhelming majority of food allergy developing. And the worse your exma is and the earlier your eczema starts, the more likely you are to see food allergies and more food allergies. And Adam, what is eczema? So exma is a itchy, dry skin condition that for many people is mild and just gets better as they get older. For some, it can be much more severe and persistent. And it's characterized by inflammation in the skin and a disrupted skin barrier. So essentially what that means is that your top layer of skin, instead of tightly sticking together and keeping all the moisture and good things

Starting point is 00:15:01 in and all the germs and bugs and bad things out, instead, because of that leakiness, water is lost from the skin. And that means your skin gets dry. And those things sat on the outside of your skin, germs and bugs and things, wind up the immune system that sat just underneath the top layer of your skin and cause inflammation so you get inflammatory components as well. And that combination, that leakiness and that inflammation creates an environment where things can go a little bit skew with from an immunological perspective. I remember when I started in the specialty, there was so much debate about was this genetically programmed, was this an allergic condition itself?

Starting point is 00:15:39 But we've sort of moved past that because hopefully somebody found the gene for or eczema. So we now know that there are genes that produce something called philagrin, which is like the sticky cement stuff that sticks that top layer of skin cells together. And if you've got one not quite effective copy of that gene and you're not producing enough of the gluey stuff to stick your skin cells together, or you're producing enough of it, but it's not as sticky as it should be, then your skin barrier will not be that impervious wall. It will be leaky. And that's where you might get exome. If you've got two copies that aren't quite working of that gene, then you're more like to have more severe and persistent

Starting point is 00:16:16 eczema. And if I don't have eczema, does that mean I'm never going to develop an allergy? You're much less likely to, but we do see people not commonly who don't really report any exsmen early childhood who still go on to get food allergies and certainly other allergies as well later. We've talked a lot so far about food allergies, but the other allergy that I think is really prevalent is hay fever or seasonal allergies, as it's called, and a lot of the rest of the world. Is that a similar story? Has that also been increasing? You said at the beginning that you didn't think our hunter-gatherer, ancestors were sort of sniffling while walking across the African savannah?

Starting point is 00:16:52 Yeah, you can sort of dig into antiquity and find occasional cases of things that sound like there were probably allergy. I think one of the Roman emperors, Britannicus, supposedly didn't lead his army into battle because he was allergic to horses. Who knows what the real story was. But I think if you want to get a clear sense of change over time, there was a pediatrician in Manchester called Bostom. in the early 19th century, he had seasonal allergies. He recognised the relationship between his blocked up itchy, runny nose and itchy eyes and the pollen season. And so he set about finding other people so that he could send a letter to the Lancet to describe hay fever. And it took him nine years to find another 28 cases. He was either extraordinarily antisocial or there just weren't many people around who suffered from the same problem. Now, whenever I tell this story when I'm giving a talk, I'll ask the audience to stick their hand up, do you have hay fever? And it will typically be between 20 and 30% of the adult population. So something has happened,

Starting point is 00:17:50 and you can't put this down to genetics because we are talking about, you know, no more than the 200 year period where this has gone from being, I guess, a medical curiosity to something that is the blight of a significant proportion of people's summers. And so when did it start to increase and go from like vanishing the rare, you're now saying 20 to 30% of all adults. Yeah, I think you can probably start looking at the post-war period when we started to see more asthma, more hay fever, more eczema. So there's reasonably good data looking at different centres and different time points to suggest that there was a big increase, you know, through the 60s, 70s, 80s to sort of modern day levels, whereas the food allergy surge appears to have happened after

Starting point is 00:18:34 that. This does seem to be more of a post-war for not. I think a lot of people have quite mild allergic responses to the pollen. Absolutely. A little bit of an irritation. Is this like a sort of impactful issue for some people? It absolutely is. So I think this is one of the challenges that allergy has in terms of PR. We all know people who have got relatively mild hay fever because there's a huge number of

Starting point is 00:19:01 them around. And if they just take, as I said, certain family members, if you just took your antihistamines, you'll be fine and they would be. But amongst the people who suffer from nasal allergies, for example, there is a 15, 20% group where these are really significant and they have a genuine impact on their, not just quality of life, but real difference on their outcomes. So for example, if you're a 16-year-old in the UK, given that we have the highest rates of hay fever and nasal allergies probably in the world, it does seem a little strange that all of our major public exams are set right in the middle of the grass pollen season, which is the most common allergen to drive

Starting point is 00:19:44 hay fever. In the UK, people will do their practice exams in the Christmas period when, of course, there's no pollen around, and they'll then have the actual exams in May and June when pollen levels are particularly high. And if you have hay fever, one study demonstrated that you were 50% more likely to drop a grade from your mocks to your actual exams than somebody who didn't have hay fever. I guess it would be the same for being at work in the summer versus the winter. So you look at productivity and it has an impact on that. You're much more like to be off sick because of your hay fever. It affects your reflexes when driving and it's been shown that if you've got significant hay fever

Starting point is 00:20:24 and you're taking certainly sedating antihistamines, which many people are still recommended to take, which is a big no-no, you shouldn't. But if they're taking them, their driving reflexes will be equivalent to somebody who's on the limit drink driving wise for alcohol. So, you know, for people with proper hay fever, it's a real problem. And if you've got grass and tree pollen allergy, that can mean that almost six months of your year are meaningfully affected by this problem. I'm thinking that the Americans calling the seasonal allergies are actually right in this term we use in the UK hay fever, which is a very strange phrase since I've never. ever seen any hay and there's no fever. You're saying almost takes away how serious it might be for people who've got sort of more extreme responses to it. I think absolutely, yeah. So it's easy

Starting point is 00:21:11 to consider it something trivial, but for a material minority, it's far from trivial. I'd love to come back to the other allergy that we talked about in the quick fire at the beginning, which is one that I've had some personal experience with, which is I have been told in the past by doctors that I was allergic to penicillin. But you said right at the beginning that, basically most people who think they have a penicin allergy don't. It's monumentally overdiagnosed. And the reason is, is when you ask somebody who has that label of penicillin allergy and give you a bit of context, about 10% of UK people will have that label somewhere on their

Starting point is 00:21:48 medical notes. They've been told, don't have penicin, you're allergic to it. And we've replicated that. We, in fact, very soon after I started my job at the Everlina London Children's Hospital in 2006, One of the first studies we did was exactly that audit. We audited everybody coming in as an inpatient to the hospital, and literally bang on 10% of children were already labeled as being penicinin allergic. And would this be similar across the West world?

Starting point is 00:22:11 Yeah, absolutely. And very similar studies from Europe, from the US, from Australia, very, very similar. And then when you ask people, where did this come from? Why have you been told to avoid it? The story is almost invariably it's the same. It's when I was little, which means it's a third-hand story, because the individual can't remember it themselves. When I was little, I wasn't well, I was given antibiotics,

Starting point is 00:22:34 I came out in a rash, and somebody put two and two together and said, you've come out in a rash because of the penicillin, when in fact we all know that small children with infections often get rashes. So huge potential for overdiagnosis, and that's compounded by the fact that there aren't relatively easy allergy tests that you can do that would just confirm it. So essentially you get told you're allergic based just on the story, And it never gets challenged. So you go through the rest of your life, always being given

Starting point is 00:23:01 second-line antibiotics, often which are both more expensive and unpleasant. So typically in a UK primary care, that means you'll be given something called erythromycin, which is way more likely to make you sick, it's horrible. You're more likely when you show up in an emergency department with a nasty infection for there to be delaying you're getting the right antibiotics because people can't give you the normal first lines because the normal first-line antibiotics are either penicillins or cousins of penicillin where we know there's a chance of cross-reactivity. And this label holds for the whole of your life. So there's 90-year-olds with all sorts of issues being given different antibiotics

Starting point is 00:23:36 because of something that's based on the most spurious of evidence from 88 years earlier. So how many people do you think actually are allergic? Well, I can go further than think because the studies where you get a group of people who have been diagnosed and actually do the correct testing and do the definitive test, which is a challenge, you give them penicillin to see what happens. Pretty universally across British, American, Australian, European studies, 90% of the people label turn out not to be allergic. Now, it still remains tricky to what we call delabel those people because you have to be

Starting point is 00:24:12 able to engage with them. The only reliable test is bringing them in and giving them some penicillin in a safe environment. Now, if you were allergic to penicillin, say you're doing it within adults, I'm saying, What we'd expect to see happen. So quite quickly after being given the dose, you'd expect them to be their body to be releasing histamine and other mediators of inflammation, which will cause itchiness and hives and swelling. And for most it will be mild, but in a small proportion, it could potentially be anaphylaxis. So a potentially life-threatening serious allergic reaction.

Starting point is 00:24:44 Hence, you can't just say to people, there, you'll probably be fine and you're not allergic, so just do it. because you'll get it wrong one out of ten times. So they need a history taken from somebody that knows the right sort of questions to ask. And often you can't get much sense back because they'll say this was 40 years ago. I have no idea. If it's a recent thing, I can ask things like, was it the first time the child's ever had antibiotics? Because we know that you need to develop sensitivity first before you can react next time round. So classically, if the story is my child had penicillin antibiotic,

Starting point is 00:25:20 once was fine, but immediately after the first dose of the second course, they came out in hives and an allergic reaction, I'll be saying, okay, that's a good story and I'm not going to bring you in to try it because chances are you are allergic. But when as it usually is, my child's actually had three courses of antibiotics, halfway through a course of another different antibiotic, they got a bit of a rash that lasted for a few days and continued even after they'd stopped the antibiotics and actually has had a different penicillin derivative on another occasion and been absolutely fine. That kidney is a very brief, sit in your waiting room, have some penicillin, delabel. So, Adam, if you're listening to this and you've been told you're allergic to penicillin

Starting point is 00:25:59 or you know somebody who is, what should you do? I think, firstly, find out what your origin story is. That often means speaking to your parents, because chances are this label appeared when you were too young to remember it yourself, and find out whether it fits with that likely narrative of I was a small child, wasn't well, was given antibiotics, came out and a rash, and that was it. And then speak to your GP about whether it's worth getting a further assessment. Now, in some areas, there are really, really good services being developed to help delabel because it makes sense on a population level to get past this. In others, it's going to be harder work to find somebody to support you doing that.

Starting point is 00:26:38 But you should definitely be raising it because it doesn't suit anybody your healthcare provider or you to be mislabeled. We've sort of covered a lot of different allergies here. And one thing I was struck by is across all of them, you've talked about this really big rise, whether that was your example of going to school. It was like one kid who had a peanut allergy, and now it's like a quarter of the school or the fact that 200 years ago you couldn't find somebody who had these seasonal hay fever allergies. What's changed? So the prevailing theory for many years was the hygiene hypothesis, what also knows the clean child theory, which is one of these theories that's absolutely entered the public consciousness and is very hard to shake. But actually it's got huge holes in it. So the idea is that there was a birth order effect that was noticed in the 1980s by an epidemiologist called Strachan. And he observed that the older child in the family seemed more likely to have allergies than younger children. And the explanation for this was, well, given modern living and the difference between how we live now from, you know, 100 or 200 years earlier and the lack of threats from different

Starting point is 00:27:53 microbes that there is these days, that that first child had relatively little pressure on their immune system to develop quickly. And consequently, the immature immune system would develop inappropriate responses. It basically needed to find some sort of trouble because it couldn't find cholera or typhoid or anything really nasty to direct itself at, you've got these inappropriate allergic responses. Whereas the younger children in the family were brought into an environment where they had older siblings bringing all the bugs and germs that they got back from nursery. So much earlier in their life, their immune system was forced to mature because it was exposed to more and that more rapidly maturing immune system was less likely to then go on and

Starting point is 00:28:33 develop allergies. But big holes in that. So firstly, large birth cohort studies, some of them showed that effect, not all of them. It was absent in other places. And over time, it simply became apparent that that was an overly simplistic view. If you now look, recently, actually, just in the last few months, there's been a meta-analysis, a huge study looking, pulling together, lots of different studies, looking at what are the underlying risk factors for having food allergy, for example. And it shows a load of things. And this is looking at hundreds of studies that cover millions of patients. And there's themes to the risk factors. There's genetic things. So having a family history puts you more at risk of getting

Starting point is 00:29:13 allergies. So clearly there is a genetic component to this. Then there's things like the exma story that we talked about. So the presence of exma and other allergic conditions. And then there's the really interesting ones that start pointing pretty clearly towards a microbial story as well, around exposures. There are now increasingly studies showing that there is a difference between the gut bacteria, the microbiome, and in fact, not just the gut bacteria, but skin bacteria, nasal bacteria, because you have microbiomes,

Starting point is 00:29:43 not just in your gut, but on your skin, in your respiratory tract, that there are differences between allergic children and children who don't get allergies. Now, I don't think what we've really nailed down because we're absolutely in our infancy of our understanding around

Starting point is 00:29:55 this relationship between our microbiome and allergies is whether people who have a tendency to allergies, therefore have a certain type of gut bacteria, or whether having a certain type of gut bacteria leads to you getting allergies. That's really hard to disentangle and it's going to take a long time to do that. But then, of course, as you'll know, anyone in this space knows, this is such an almost overwhelmingly complex area because we're not just talking about a, we often refer to a diverse microbiome or a less diverse microbiome,

Starting point is 00:30:28 the idea that there's a binary, if you've got a more diverse group of bacteria colonising your gut, then yes, that does seem to be associated with a less allergic profile, whereas having a less diverse microbiome and profile does seem to make you more likely to have allergies. There's so many different types of bacteria that are all producing lots of different things, all of which which interact with each other, trying to disentangle this is hugely complicated. And if you look at the league tables for allergic disease, it's very striking that at the top are Australia, New Zealand, Canada, UK,

Starting point is 00:31:03 US, geographically very disparate places, but culturally very similar places. I always challenge anyone that says, you know, no, no, I really believe in the hygiene hypothesis. And it's like, well, what about Switzerland? You know, where is somewhere that has got really low infant mortality rates, that has got really low rates of, you know, infection and that sort of issue amongst their childhood population? Why are they not up there in terms of allergy? Because they're not. They're sitting somewhere in the middle in terms of prevalence rates. So I think what we can confidently say is that this is complex and multifactorial. There's certainly a genetic component.

Starting point is 00:31:40 Of course there is because we know there are allergic families. There's certainly really important specifics, for example, the presence of eczema, making you more likely to get food allergies. And I think we can also be very confident that the microbiome plays a really, really important role. but I think the real challenge is and the real question here is, so how can you then leverage that to make less people allergic or to make the people that are allergic less allergic? Before we move on, why are you so confident that the microbiome plays an important role?

Starting point is 00:32:12 Because consistently you find that there's differences between people with allergies and without allergies and are improved understanding at an immunological level of how our immune system develops tolerance is clearly highly dependent on the environment in your gut and elsewhere that is hugely informed by which bugs are present. I'll try and give a very, very quick example. If you go to mouse models, so sort of in the lab with mice, you cannot induce tolerance in mice who are brought up in completely sterile environment. So ones where they have no microbiomes and no gut colonization of bacteria, you can't get those mice to be okay with foods. They react to everything. They're basically sort of allergic or intolerant to everything. Over hyperreactive in terms of

Starting point is 00:33:05 their responses to things, whereas regular mice that do have a gut bacteria, if you feed them allergenic foods very early, they'll develop tolerance to them. Whereas if you rub those foods into their skin, into a braided skin, you can make them allergic to it. Going back to what we talked to about earlier with the food allergies. And so what you're saying is, you've got these two mice, one with microbes and one without, and the ones with microbes can end up eating peanut butter. But if you haven't got the microbes, you're never going to be able to eat the peanut butter. So essentially, we need the right sort of gut bacteria to develop an appropriate relationship

Starting point is 00:33:39 with the outside world. And actually, more recent research is suggesting actually that your siblings are really important here. And that might explain a degree of birth order effect. That if you've got lots of friendly bacteria and lots of children, you bring another small child into that environment, they'll often share those. bacteria and that can help develop a healthier microbiome for that younger child and maybe protect them from allergies. So when you start viewing things through the lens of the microbiome,

Starting point is 00:34:03 a number of things start falling into place. But if, you know, to then go back and, you know, push back the other way, I was involved in a study a few years ago where we got hundreds of infants. This was across the world, hundreds of infants who had milk allergy. And if their mother wasn't able to breastfeed, they'd be put onto these hypoallergenic formulas. And they were randomized to either getting one that had pre and probiotics in and the other one that didn't. And we showed that if you got the one with pre and probiotics in, it would give you a healthier, in inverted commas, a more diverse with the right sort of bugs microbiome. But it just didn't make any difference to the outcomes. We were hoping to show that if you gave the right bugs to the right children

Starting point is 00:34:42 with milk allergies, they would outgrow their milk allergy faster, be less likely to get other emergencies, just didn't make any difference. So understanding it, but then knowing how we can influence it in a way that's going to improve outcomes to very, very different questions. That's fascinating. And I think if I'm playing it back, what you're saying, Adam, is we know that the microbiome is really important in terms of ensuring that we don't have these allergies. We don't yet know exactly what you need to have. But what we do know is that somehow it's not the situation we had, you know, 100 years ago because you said there has been this explosion and all of these allergies. Yeah. And another little interesting bit of evidence, recent stuff.

Starting point is 00:35:21 looking at dietary diversity in mums and infants as well in terms of the risk of food allergy turns out to be important. And there's now really, really clear evidence that mums who have a broader and more diverse diet with all sort of healthy different food groups and with a child who then also is introduced to more foods early and a breadth of foods, we see less allergies developing. I'm conscious that we haven't really clarified the difference between like an allergy, a sensitivity and an intolerance, and these words are thrown around a lot. Could you help me to understand that? Sure. They are very different things. The terminology is really important, but the bottom line is that an allergy does involve your immune system, and intolerance doesn't involve your immune system.

Starting point is 00:36:08 Now, the most common food intolerance is lactose intolerance. It's really common. We have a gene that allows us to produce something called lactase, which is the enzyme in our gut that breaks down lactose, which is the sugar in milk. And if you don't have enough of it, then when you have lactose, so you have a glass of milk, then the sugar can't be broken down properly. And that means that you create a lot of gas in your gut and basically become farty and bloaty, and you get an upset tummy for 20 minutes afterwards. And that can happen transiently when you're younger if you get an infection in your gut, because the infection causes inflammation in the lining of the gut, which is where that lactase enzyme is stored.

Starting point is 00:36:50 It's eroded away because of the infection, and it takes sometimes up to a month or so to recover. So you can have a viral gastroenteritis, get diarrhea and vomiting for two or three days, and then find that you feel better, but when you go back to your normal diet, you're still getting really loose poos and stomach cramps and bloating, and that's because you've eroded away your supply of lactase.

Starting point is 00:37:11 You can't break the lactose down, whereas if you switch to lactose-free food, you'll be absolutely fine. And then within the month, things go back to. normal, and that's very common in early childhood. But then genetically, most people in the world are programmed to not bother to produce that lactase enzyme beyond childhood, because of course, once you don't need your mother's milk anymore, we're not really designed to drink the milk of other species. That's a slightly bizarre thing to be doing. But then there's a group of people

Starting point is 00:37:37 who have a mutation in that gene, which means that they don't stop producing the enzyme. They continue to produce it throughout adulthood, so they can break down lactose throughout their lives, and that's most Northern Europeans, whereas most Asians and Africans, there are interesting exceptions dotted around, but most can't tolerate it. Hence, you'll see the difference in diet. When you look at the diet of an adult Chinese person in China, there's not any lactose containing food, because nearly everybody is lactose intolerant, whereas in Western Europe, we've developed a very lactose-heavy, dairy-heavy diet because we're fine with lactose. So that's an intolerance. It's not dangerous. It's unpleasant. And there's a range of other

Starting point is 00:38:16 intolerances that fall into different categories, but none of them are dangerous and none of them involve your immune system. And that's in stark contrast to allergies and when it comes to food allergies, it's your immune system that's the problem. So your immune system has produced allergic antibodies that recognise that food so that the next time you eat it, they will spot that you've eaten that food and trigger a reaction, which is usually mild, but can be catastrophic. So it's potentially dangerous. And this is one of the reasons why food allergy is so challenging as a condition to manage because fatal anaphylaxis, thankfully, is very, very rare, even amongst allergic populations. You've used that word anaphylaxis a few times. I've no idea what it

Starting point is 00:39:00 means. Okay, so anaphylaxis is a serious allergic reaction that is potentially life-threatening. Now, a common definition would be that it's an allergic reaction that involves either your breathing, so airway or breathing are affected or your blood circulation. So you could have a persistent cough or wheeze or if your blood pressure drops, you might feel lightheaded, dizzy, you might collapse. Any of those symptoms, that means this is the real deal. This needs to be taken seriously. You require adrenaline as quickly as possible, injected intramuscularly into your muscle in order to make you better. And whilst most people will recover without treatment, there is a small chance that without that adrenaline treatments, things will get worse and you could potentially die from it. So it's a

Starting point is 00:39:46 medical emergency. I'm reminded of the question I asked at the very beginning where I said, you need to all allergies happen in childhood and you said no. And I would say at a personal level, I do have these seasonal allergies, this hay fever fairly seriously now. And I don't remember having it at all until I was an adult. In an adult allergy clinic, there's much much more of a respiratory focus. So it's much more around asthma and severe allergic rhinitis seasonal allergies. But there are also the children who grew up and still have their food allergies. And then there are a cohort, a small cohort of older people who will develop food allergies as they get older. And they can be broadly divided into two sorts. Now, actually,

Starting point is 00:40:31 the largest group are people who have what we call cross-reactivities. So they've got hay fever, really common and give you a good example, birch is their problem. So they're allergic to birch pollen, one of the more common pollens to be allergic to. There are many fruits and vegetables that contain in them, often close to the skin of the fruit and vegetable, that looks pretty much identical to birch pollen.

Starting point is 00:40:53 And when they eat that food, in the raw form, they'll get a little tingly reaction. And it can be quite unpleasant, but it's very, very rarely dangerous in any way. So anaphylaxis from what we call pollen food syndrome, that cross-reactivity, is really uncommon. But it will sometimes stop them from eating foods and sometimes the range of foods can be really, really large. So all stone fruits and a load of vegetables and nuts and it can

Starting point is 00:41:16 really interfere with your day-to-day diet. But it's not seen as a dangerous allergy. So it needs diagnosing and it needs counseling to support people to help manage it. And one of the important things is that the protein that looks very similar to pollen that you find in foods is really unstable, which means it breaks down very quickly as soon as it's in your mouth, which is why it doesn't cause severe reactions. And it only requires a little bit of processing, such as cooking or heating, to break it down. So the classic person with pollen food syndrome will say, I've got hay fever. I used to eat apples all the time. Now I've noticed that when I have a raw apple, it gives me a real tingle. But if have apple pie or apple juice that's been pasteurized, I'm absolutely fine. And that will be a really classic story.

Starting point is 00:41:59 So there's that group, that's common. But they're less of a worry than the a smaller group of people who will say, I've eaten fish all of my life, no problem, and suddenly I had a mouth full of cod, and I had an anaphylaxis as a consequence. So they develop from nowhere, and we see it more commonly with fish and shellfish to things they've previously been absolutely fine with, and then they have an allergy that is potentially dangerous, and they have to carefully avoid it. And do we know why that's happened? Sometimes an immunological event can lead to a lot of tolerance. So sometimes there's an illness that somehow during that something happens in your immune system means that something that used to

Starting point is 00:42:36 be fine suddenly isn't recognised in the same way by your immune system. And often you'll get that in the story, but of course it's always hard to be certain that that's the real cause. And it's incredibly frustrating because they've often thought that they've dodged the bullet completely and suddenly it appears from nowhere. If you know someone who says they think they've developed an allergy or is reacting badly to foods or environments they never used to, send in this episode. It explains why this is happening and what to. do next. Could we talk about gluten? Because that hasn't come up. And that I think is maybe the one sort of allergen that I hear about all the time and where I understand, you know, there are

Starting point is 00:43:15 people who are genuinely allergic to it, but then there's a much broader set of people who are worrying about it as an intolerance. What's the reality there? Well, the really important thing is to clarify the difference between allergy to wheat or gluten and celiac disease, which is a different type of disease is often classed as an autoimmune disease where there is a specific hypersensitivity, so oversensitivity to wheat, but not in the way that you would get with a typical allergic reaction. So you do get people with genuine wheat allergy who like somebody with a peanut allergy when they eat wheat or gluten-containing foods, they will come out of hives and itchiness immediately. But then there's also the not uncommon condition of celiac disease. So people who, when they have

Starting point is 00:43:55 gluten, whether it's in wheat or rye or barley in their diet, it will cause an eating. inflammation in their gut that will make them unwell but in a more chronic way. And if it's not diagnosed and gluten isn't excluded, they're at risk of developing lymphomas, like serious medical issues in the longer term. Whereas if they exclude it from their diet, they'll feel an awful lot better. And often there's quite significant delay in the diagnosis and it will often not present itself to a little bit later in life. So those are two quite distinct and in a medical sense, very easy to identify groups because there are highly specific tests that will confirm you have this problem. But those are both completely distinct from people who simply say,

Starting point is 00:44:35 I feel better when I exclude gluten from my diet. And when I include gluten in my diet, I feel unwell, whether it's because they feel tired or nauseous or bloated or a whole range of different symptoms. And if that is genuinely reproducible, and we need to have an open conversation, it needs exclusion to confirm it gets better and reintroduction to confirm that it really gets worse. and testing to confirm that they don't have celiac disease, and then we would refer to a bit of a mouthful as having non-seediac gluten hypersensitivity. They genuinely and reproducibly feel less well when they have it, but they don't have celiac disease,

Starting point is 00:45:12 which means they could choose to continue to have it, and it wouldn't be dangerous, but they'll have the consequences of not feigning as well. And that's a very poorly defined group, and we've got a lot of work to do to understand that group better. You know, it's human nature, isn't it? Everybody wants to seal a bullet. I don't feel great. I don't feel at my best.

Starting point is 00:45:28 I'm tired all the time and it's probably because you're barely sleeping, you're working really hard, you have a lot of coffee and alcohol, you have a very poor diet. That's probably the answer to that. But it's really appealing to think, oh, if I just cut gluten out my diets, I'll feel a lot better. Now, nutritional scientists will always tell you that there's whatever your dietary change you make. There's usually a bit of a honeymoon period where you briefly feel better just because you're taking control of what you're doing and looking more carefully at your health. But then often revert back to where you were. and you'll often hear that story, people will take something out of their diet,

Starting point is 00:46:00 find that transiently they do feel better, but then realize actually soon enough, everything's broadly the same. But there are certain foods and gluten is definitely one of them where, as a consequence of eliminating that, you're actually having much broader impact on your diet, and it could be that that's being helpful rather than the gluten specifically. So if someone listening to thinks they have an allergy, what should they do? So if you're concerned about food allergy specifically, there is actually in the UK there's national guidance that if you go to your GP, they are obliged to sort of ask the right sort of questions to understand

Starting point is 00:46:33 what type of allergy you might be describing, organising appropriate tests and referring you as appropriate. And it's really important to do that. We know, and this was pretty shocking to myself and colleagues, only around 10% of people with food allergy in the UK ever see anyone beyond their GP about their food allergy. So that's a family doctor. Exactly, their family doctor. There are now a range of treatment options for food allergies that weren't around five or ten years ago. So it's actually really important if you have food allergy to get good advice because there are options that will really change outcomes. Now, I've seen ads for like a blood test and you can take a blood test and it will just tell you the answer of what you're allergic to.

Starting point is 00:47:15 So is that what you end up? Definitely not. The only way you can get a proper diagnosis is a combination of a proper. allergy-focused clinical history, together with the appropriate tests. Allergy tests are terrible screening tests, and getting a correct diagnosis is super important because avoiding foods you're not allergic to is a waste of everybody's time and makes life much more difficult, and not avoiding foods that you are allergic to is potentially dangerous. There are two validated allergy tests.

Starting point is 00:47:44 One is a skin prick test, which essentially looks at your immune system's response to being directly exposed to either the food or environmental allergens. So if you want to diagnose seasonal allergies or food allergies, it's a really useful test, together with a good clinical history. And there's also blood testing that looks and measures the amount of allergic antibody specific to a particular food or environmental allergen. Those are also helpful. And sometimes even all of those together doesn't quite give you enough and we'll do the definitive test,

Starting point is 00:48:13 which is what we call a provocation challenge, where if the test is saying you might be allergic, to peanut and you've never eaten it before. The only way to find out is bringing you in somewhere safe and giving you some peanuts to eat because then if you are allergic, you'll react. And if you aren't allergic, you won't react. But if you do react, you're somewhere that we can deal with that reaction. We'll only do this to kids or adults when they're already well because you're more like to have a bad reaction if you're unwell. We give them small, increasing doses so they any react to the smallest amount they're sensitive to and we immediately treat a reaction as soon as it happens. So consequently, the overwhelming majority of these food challenges lead to minor reactions

Starting point is 00:48:48 to get treated immediately. But even if there is an anaphylaxis, often it's in the form of somebody saying, oh, I'm feeling itching, I'm coughing persistently, and we'll just use adrenaline, and that settles things down very quickly. So as long as it's done in the right way by the right people at the right time, it's a very, very safe test, and it gives you a definitive answer. You've played a big role in developing something new that's called desensitization. Can you explain what that is and how it works? So this is a paradigm shift, really, in the way that we manage food allergies. And it's not a new concept. In fact, the first recorded case 1908 in London, where a child with anaphylaxis to egg was given small but increasing amounts of egg to make them less sensitive.

Starting point is 00:49:31 And it's the same principle that we use for pollen and dust mite allergies where we give people either injections or tablets under the tongue of small but increasing amounts of the allergen to make them less sensitive, to retrain the immune system, to not react at such a small amount. amount and it works really, really well for food allergy, particularly in younger children. So we'll do it in kids all the way up to 18 and there are some places where they'll do this in adults as well. But when you do this in younger children where their immune systems are more what we call plastics are basically more malleable and more open to suggestion, you can really shift somebody from being sensitive to a tiny amount and at risk of having bad reactions to being able to tolerate a large and sometimes not just a large amount, but actually be able to eat it freely, which is the real prize. When we do this in younger children with peanut allergies,

Starting point is 00:50:16 for example, not always, but sometimes we'll get to the point that they can freely eat peanut without needing emergency medication around. And that's night and day from where we were 10, 15 years ago. And can you do this at home yourself? Definitely not. And it needs careful close supervision because there is a risk associated with doing the treatment and it's only suitable for certain patients. It needs a lot of what we call shared decision making with parents as to whether this is not only something we could do, but should we do? And for some families, the right thing to do with the food allergies, avoid the food. But for some, there is an opportunity to make an intervention that has a real impact on outcomes. You mentioned here a child, but let's say I'm 30 years

Starting point is 00:50:54 old and I've got a peanut allergy. Can I be desensitized? Your options are much more limited. There are places that will offer you desensitization. There's new modalities of desensitization. So we're moving away from just saying, eat small but increasing amounts to here's a tiny little bit that you're going to pop under your tongue. And there's, in fact, just last week, we had the release of some really exciting data about sublingual immunotherapy for peanut for adults, where essentially showing that it seems to be safe to do a treatment where you put small but increasing amounts under the tongue. And the gains aren't huge. So you can get somebody to the point that they can eat a peanut, which might feel not important, but it's usually important because if you're traveling,

Starting point is 00:51:34 you know, you want to go overseas, you want to eat out, it's really hard to avoid tiny amounts. And it's usually small amounts that cause most accidental reactions. But if you can get somebody to the that they're okay with a peanuts worth of peanuts, their likelihood, if they're still telling people, don't give me anything with peanuts in, of having more than a peanuts worth a peanut is way lower than their chances of having a quarter of a peanut accidentally because somebody used the same knife from the peanut butter on the sandwich they made for them or didn't clean out the pan after a chicken satin. What about hay fever, seasonal allergies? How should we be managing that? For most people, have a chat with your pharmacist. So things like over-the-counter antihistamines,

Starting point is 00:52:12 saline nasal sprays and simple things like rubbing a little bit of Vaseline around your nostrils to catch the pollen before it goes in, not drying your clothes on the clothesline outside when the pollen seasons at its height, closing the windows at night during the pollen season, washing your hair before you go to bed so you don't transfer a pollen from your hair to the pillow to your nose. That will do the job. For the percentage of people who have more troublesome symptoms despite that, over-the-counter for children 12 and upwards, steroid nasal sprays, very safe, very effective. And for the 15% or so who are taking irregularity histamines, they're taking steroid nasal sprays.

Starting point is 00:52:48 And despite that, it's still interfering with their quality of life. There are desensitization treatments. So tablets made out of huge doses of grass pollen or tree pollen, or there's also dust mite equivalents, that you pop under your tongue every day. And over a period of time, they reduce your sensitivity. They won't eliminate or cure you, but they'll make you less symptomatic, more able to manage just with the regular medication. And the really good news in the UK is that these have received nice approval recently, which means that a really well-respected independent organisation has assessed these treatments

Starting point is 00:53:20 and said not only do they work, but it makes health economic sense for our state-funded health system to be recommending them to you. But we are a mile behind in the UK on this. And for every person who receives pollen desensitisation in the UK, about 700 do in Germany. Many other places in Europe in particular, this is mainstream management. but really in the UK there was a huge issue about access to these treatments. In the US, you can go to an allergist and get allergy shots. There's much more of a culture of giving injections there because it's easy to visit an allergist in the way that it's not in the UK where it's far fewer. But the nice thing about sublingual immunotherapy, so this desensitization under the tongue, you just do it at home.

Starting point is 00:54:00 You don't need to be seeing your allergist. It's literally a tablet every day goes under your tongue. It's for three years. It's a long course of treatment. But it gives you long-lasting benefit. it's disease modifying, and this is the holy grail analogy. It doesn't just work while you're taking it like a nasal spray and antihistamine will. If you do the full course of treatment for years afterwards, your symptoms will be reduced

Starting point is 00:54:19 because you've actually changed your underlying immune response. For people who aren't doing that, but are having this bad enough that they're taking antihistamines all the time, is there like a downside from taking an antihistamine every day for six months of the year? As long as you're taking the right one, there isn't. but if you're not taking the right one, there is. So the old-fashioned ones, the sedating first-generation short-acting antihistamines, which basically means pyroton, which you shouldn't be getting recommended when you go to see your pharmacist, but sadly it still seems to happen that you are. So chlorfenamine, things like that. They firstly will impact on your alertness and reflexes and

Starting point is 00:54:58 those sorts of things. They don't make you feel that much better. They're not particularly good at managing your hay fever. And long-term use has been linked to dementia in large studies. essentially they should just not be available. Second generation antihistamines, so long-acting, non-sedating ones. So that's satirazine, loratidine, phyxophenidine, and those are sort of the drug names,

Starting point is 00:55:19 and you can get the generics and much cheaper than buying the proprietary ones. They don't have any of those downsides. The long-term studies strongly support that they're very safe and there's no link to things like dementia. They've got a really good safety track record. And they're more effective.

Starting point is 00:55:34 So definitely start there. and avoid those sedating first-generation antihistamines. So I am basically popping one of those from April to October every day. That's absolutely fine. You know, you have to make your own risk assessment based on do I feel better or not taking them? And given that they're very safe medication, and that's why they're available over the counter, then it's a reasonable thing to do if you do feel better on them.

Starting point is 00:55:58 You've been very involved in a pretty big transformation of care for allergy treatment for certain allergies. what do you think the future of allergy treatment and prevention is going to look like? I think the first thing says it looks really exciting. I mean, we're in a position I would never have imagined 20 years ago when I started in this field that we'd be in, which is not only you'll be able to diagnose very effectively, but we actually have treatment options, never mind a single treatment, we can actually discuss different ways of treating. But we're starting to see a little bit of a divergence happening.

Starting point is 00:56:29 Desensitization treatment, so for example, peanut allergy desensitization has not proved a profitable area for pharmaceutical companies. And as a result, pharmaceutical companies are looking at different ways of managing allergy in a way that there will be reliance on medication. It's not changing your allergies or in any way redirecting your immune system. It's just essentially blocking the effect. And so you're stuck on the medicine and it's expensive. We're not seeing the same investment in this other way of treating things, just using food,

Starting point is 00:57:00 which of course means it's a lot cheaper, to change the underlying immune response. in a more sustainable long-term way, which intuitively to me as a doctor feels like a better way of doing it. But the important thing is, is things are improving. And I often say to patients, when we start on these courses of treatments, in a way, this is sort of a stop gap. So even if this does any manage your allergy for a few years, I'm sure there's going to be other options in a few years as well, because there's so many more options now than there were five and ten years ago. Well, on the one hand, I find it really depressing that you're talking about another area where pharmaceutical companies are only interested in treating the symptoms and never treating the disease because it's really

Starting point is 00:57:38 profitable to keep giving you a drug that you'll take for the rest of your life. On the other hand, hearing how excited you are about all the new things that are coming is really fantastic. I'm going to wrap up with the short summary. Please correct me if I've got any of this wrong. So the thing I'm most struck by is that 10% of the people listening to this show have been told they have a penicillin allergy. So in other words, if there's 100 people listening, 10 of them have been told

Starting point is 00:58:04 they have a penicinal allergy. Actually, only one of them has a penicine allergy. And that means that basically nine of these people are going to be taking terrible antibiotics that are going to wreck their microbiome for no reason. And they can switch to something that's much less harmful when they need antibiotics. So that's really shocking. And I think anyone who's listening in this situation should definitely go out and try and get that tested because we know how important our microbiome is if you've been listening to this show. Second thing I'm really struck by is you're sort of saying, well, actually, there was this hygiene hypothesis and the idea was that the reason why you have all of these allergies is because we kept our houses so

Starting point is 00:58:38 clean. We're saying, actually, we don't really believe that anymore, or so it's only a small part of the total story. But we do know more and more that our microbes are a sort of central part of this story. And you explained that the reason why we really know this is because if you have no microbes, actually, basically you're allergic to everything. And we know that because we can get mice with no microbes and they're basically allergic to all food. You give them their microbes, you let them eat the food and suddenly they're like, oh no, peanut butter is delicious. I have no problems, which is fascinating. So we understand that there's something going on in terms of our modern life because none of these sort of allergies, you know, existed a few hundred years ago.

Starting point is 00:59:23 Now we see these extraordinary things, you know, one in 50 kids have peanut allergy. 20 to 30 percent of adults have these seasonal allergies or hay-fews. fever. So this is profoundly different. But we have made a lot of progress in understanding the underlying science of what's going on. And I was struck by you saying that in general, we're most allergic to food that's sticky, which is quite funny. I've never heard that before. And you're like, well, peanut butter, hummus. It's obvious. And I'm like, why is it? Well, because it sticks to your skin. And therefore, what happens is that it's getting in through your skin. If for some reason you have eczema or you have some other reason that your skin is porous and

Starting point is 01:00:02 particularly happens when you're a baby, and then your body sort of goes to hyalone. So this thing has come in and it's not been eaten, it's therefore some sort of dangerous pathogen and we've got to fight back. And you said that, again, like time back to like our broader understanding of things, we don't understand exactly why this happens for some kids and not. But you said there was some interesting data in children where their moms have a broader, more diverse diet, their kids actually have less allergies. And so again, somehow there's this link through between the food we eat and our microbiome and these allergies.

Starting point is 01:00:36 And then finally, I think we ended with this incredibly exciting story about desensitization, that you've been one of the driving forces behind, that this is a really huge breakthrough. And so there are all of these treatment options for things that we used to think you just had to live with, like a peanut allergy or these seasonal allergies. And it takes a long time. So I think you said it would take me three years of being treated for my hay fever. which is a long time, but at the end, genuinely, like, my immune system has been shifted. And it does remind me again a bit of the story of changing your diet with Zoe, for example,

Starting point is 01:01:11 that you can sort of have a profound change to the way that your body feels and is, even in something as extreme as food allergy. There's something really excited about that. Sounds spot on. I'll end this episode with something I think you'll like, a free Zoe gut health guide. If you're a regular listener, you know just how important it is to take care of your gut. Your gut microbiome is the gateway to better health, better sleep, energy and mood. The list just goes on.

Starting point is 01:01:41 But many of us aren't sure how to best support our gut. I wasn't sure before doing Zoe, which is why we've developed an easy-to-follow gut health guide. It's completely free and offers five simple steps to improve your gut health. You'll get tips from Professor Tim Specter, Zoe's son. scientific co-founder and one of the world's most cited scientists, plus recipes and shopping lists straight to your inbox. We'll also send you ongoing gut health and nutrition insights, including how Zoe can help. To get your free Zoe gut health guide, head on over to zoe.com slash gut guide. Thanks for tuning in and see you next time.

ZOE Science & Nutrition - Is your gut making hay fever, seasonal allergies, eczema and food intolerances worse? Here are 5 ways to fight back | Prof. Adam Fox

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