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

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. 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 or something else entirely? In this episode Adam Fox, professor at Kings 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? 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. 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. Do most people who think they have a penicillin allergy really have one? 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 allergies are getting increasingly common. When I was young I 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 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 1500 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 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 you know when they were coming over to play that a number of them would present us with their EpiPens when they arrived and you know 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 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 trebling in the number of people presenting to emergency departments with severe allergic reactions. So this is a very significant increase year on year 6 or 7% to get to those sorts of amounts and if you dig in to well why is that happening is it 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 a hundred or 200 years into Lancet papers 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 a bit mean on the peanut. No you're not there's a couple of reasons why peanut seems to get all the headlines so firstly it is a really important allergen about one in 50 kids in the UK 2% we think have a peanut allergy it's amongst the 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 model in 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 it is responsible for some of the fatal anaphylactic 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 allergies milk? The most common cause of fatal anaphylaxis the most common cause of anaphylaxis in younger children is milk it's not peanuts. Now couple of reasons so firstly milk allergy in younger children is much more common than peanut allergy but most of it is outgrown so amongst an adult population you're going to find more persistent allergy from childhood to things like peanuts and tree nuts and sesame 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 so curious you said there has been this big rise is a really important part of the allergy 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 cashew pistachio walnuts 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 grow up with 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 a 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 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 on 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 eczema an 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. You're saying we tend to develop this when you're a very small child 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 on to 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 it somehow it's getting in because the skin barrier hasn't blocked it out and my immune system is like hang on 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 eczema or no eczema 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 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 wall 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 recognize 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 because genetically you don't have the glue that sticks your skin cells together then there was 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 infants has never eaten it before why is the skin not keeping these things out there's a lot of misinformation when it comes to nutrition from toxic diet culture to a broken food system it's no wonder so many of us feel stuck overwhelmed or misled and not as healthy as we want to be if you feel like you've tried everything to improve your health and still don't know whose advice to follow it's time to listen to your gut after eight years spent measuring 300 000 gut profiles zoe has released a brand new app and gut health test to show you exactly what your body needs to thrive and to help you build healthy eating habits that actually stick with AI food tracking you simply snap a photo of your meal to get personalized insights into how your food will impact your body you can even identify which processed foods in your fridge are high risk for your health and which aren't a worry the app will help you eat more mindfully allowing you to track progress with daily diet feedback from your in-app AI nutrition coach along with the app your gut health test can tell you how to improve your gut microbiome with personalized advice to help you support your gut function and help increase your abundance of good gut bugs this isn't the latest quick fix miracle plan or crash diet likely to make you feel worse than when you started this is a personalized nutrition app and gut health test backed by real clinical results and the world's largest nutrition study ready to join the gut health revolution go to zoe.com 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 in that we see who have eczema it's from that population that we see the overwhelming majority of food allergy developing and the worse your eczema 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 eczema 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 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 that top layer of your skin and cause inflammation so you get an 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 especially there was so much debate about was this genetically programmed was this an allergic condition itself but we've sort of moved past that because helpfully somebody found the gene for 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 glowy 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 eczema if you've got two copies that aren't quite working of that gene then you're more likely to have more severe and persistent 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 eczema in early childhood who still go on to get food allergies and certainly other allergies as well later we 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 yeah you can sort of dig into antiquity and find occasional cases of things that sound like they 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 Bossstock in the early 19th century he had seasonal allergies he recognized 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 anti-social 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 percent of the adult population so something has happened 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 vanishingly rare to you're now saying 20 to 30 percent of all adults yeah I think you can probably start looking 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 centers 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 that this does seem to be more of a post-war phenomena I think a lot of people have quite mild allergic responses to the problem like 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 them around and if they just take as as I said certain family members if you just took your anti-histamines 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 on their outcome 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 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 and you're taking certainly sedating anti-histamines 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 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 and this term we use in the UK hay fever which is a very strange phrase since I've never seen any hay and there's no fever your 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 to consider it something trivial but from 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 I've had some personal experience with which is I have been taught 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 penicillin allergy don't yeah it's monumentally over diagnosed 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 medical notes they've been told don't have penicillin you're allergic to it and we've replicated that we in fact very soon after I started my job at the Everlean 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 penicillin allergic and would this be similar across the west world 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 what 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 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 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 delay and 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 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 to that? 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 labeled turn out not to be allergic now it still remains tricky to what we call delabel those people because you have to be 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 with an adult someone's thinking like what would you 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 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 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 10 times so they need a history taken from somebody that knows the right sort of questions to ask and often it's you can't get much sense back because they'll say this was 40 years ago I have no idea you know 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 around so classically if the story is my child had penicillin antibiotics once was fine but immediately after the first dose of the second course they came out and 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 is 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 had been absolutely fine that kidney is a very brief sit-in-your-waiting room have some penicillin de-label. So Adam if you're listening to this and you've been told you're allergic to penicillin 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 in 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 de-label because it makes sense on a population level to to get past this in others it's going to be harder work to find somebody to to support you doing that but you should definitely be raising it because it doesn't suit anybody your your healthcare provider or you to be mislabeled. We sort of covered a lot of different allergies here and one thing I was struck by is that 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 or also known as 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 in you know 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 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 and 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 develop allergies but big holes in that so firstly large birth cohort studies whilst 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 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 allergies so clearly there is a genetic component to this then there's things like the eczema story that we talked about so the presence of eczema 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 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 this 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 you know anyone you know 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 the idea that there's a binary if you've got a more diverse group of bacteria colonizing 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 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 australian, new zealand, canada, uk, 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 child population why they're 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 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 the microbiome plays an important role because consistently you find that there's differences between people with allergies and without allergies and our 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 try and give a very very quick example if you go to mouse models so sort of you know in in the lab with mice you cannot induce tolerance in mice who are bought up in completely sterile environments 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 a sort of allergic or intolerant to everything over hyper reactive in terms of 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 it 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 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 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 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 and 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 with milk allergies they would outgrow their milk allergy faster be less likely to get other allergic diseases 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 a hundred years ago because you said there has been this explosion and all these allergies yeah and another little interesting bit of evidence recent studies 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 abreast the 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 sure they are very different things and the terminology is really important but the bottom line is that analogy does involve your immune system and intolerance doesn't involve your immune system 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 guts because the infection causes inflammation in the lining of the gut which is where that lactase enzyme is stored it's eroded away because of the infection and it takes sometimes up to 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 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 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 lactase 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 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 recognize 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 allergies 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 had no idea what it 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 light-headed dizzy you might collapse any of those symptoms that means this is 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 was a small chance that without that adrenaline treatment things will get worse and you could potentially die from it so it's a medical emergency i reminded of the question i asked at the very beginning where i said you know to all allergies happen in childhood and you said no and i would say at a personal level i do have like these seasonal allergies this hay fever fairly seriously now and i don't remember having it at all until i was an adult yeah in an adult allergy clinic there's 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 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 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 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 I have apple pie or apple juice that's been pasteurized I'm absolutely fine and that will be a really classic story so there's that group that's common but they're less of a worry than the 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 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 loss of tolerance so sometimes there's an illness that somehow during that something happens in your immune system means that something that used to be fine suddenly isn't recognized 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 them this episode explains why this is happening and what to do next. Can 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 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. It's 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 the hives and itchiness immediately but then there's also the not uncommon condition of celiac disease so people who when they have gluten whether it's in wheat or rye or barley in their diet it will cause an 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 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 they feel tired or nauseous or bloated or a whole range of different symptoms and if that is genuinely reproducible and you know 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-celiac gluten hypersensitivity they genuinely and reproducibly feel less well when they have it but they don't have celiac disease which means they could choose to continue to have it and it wouldn't be dangerous but they'll have the consequences of not feeling 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 everybody wants to silt a bullet I don't feel great I don't feel at my best I'm I'm 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 can't 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 find that transiently they do feel better but then realize actually soon enough everything's broadly the same but there are certain foods and glutes and stuff and 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 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 what type of allergy you might be describing organizing appropriate tests and referring you as appropriate and it's really important to do that we know and this is a 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 like 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 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 it makes life much more difficult and not avoiding foods that you are allergic to is potentially dangerous there are two validated allergy tests one is a skim prick test which essentially looks at your immune system's response to being directly exposed to either the food or environmental allergens 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 which is what we call a provocation challenge where if the test is saying you might be allergic to peanuts 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 only 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 that get treated immediately but even if there isn't an anaphylaxis often it's in the form of somebody saying oh i'm feeling it in i'm coughing persistently and we'll just use a adrenaline 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 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 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 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 for example not always but sometimes we'll get to the point that they can freely 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 he's 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 it's some 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 child but let's say I'm 30 years 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 your 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 point that they're okay with a peanut's worth of peanuts they're likelihood if they're still telling people don't give me anything with peanuts in of having more than a peanuts worth of peanut is way lower than their chances of having a quarter of a peanut accidentally because somebody used the same knife and the peanut butter on the sandwich they made for them or didn't clean out the pan after a chicken satay 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 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 season said 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 regularity histamines they're taking steroid nasal sprays 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 organization has assessed these treatments 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 desensitization 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 your 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 US in a way that it's not in the UK where there's far fewer but the nice thing about sublingual immunotherapy so this desensitization under the tongue you just do it at home you don't need to be seeing your allergist it's literally a tablet every day it 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 on antihistamine will if you do the full course of treatment for years afterwards your symptoms will be reduced because you've actually changed your underlying immune response for people who aren't doing that but are having like 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 piratom 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 chlorphenamine things like that they firstly will impact on your alertness and reflexes and 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, fexophenidine and those are sort of the drug names 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 really good safety track record and they're more effective 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. You've been very involved in like 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 are we 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. Desensitization treatment so for example peanut allergy desensitization has not proven 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 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 there 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 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 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 you know there's a hundred people listening ten of them have been told they have a penicillin allergy actually only one of them has a penicillin allergy and that means that basically nine of these people are going to be taking terrible antibiotics they're going to wreck their microbiome for no reason and they could 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 you know go out and try and get that tested because we know how important our microbiome is if you've been listening to this show. Secondly 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 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 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 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 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 oh why is it yeah 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 like your skin is is porous and particularly happens when you're you're a baby and then your body sort of goes to high loads as this thing has come in and it's not been eaten it's therefore some sort of dangerous pathogen and we 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 or not but you said there was some interesting data in children where their mums have a broader more diverse diet their kids actually have less allergies and so again somehow there's this link through between the food weed and our microbiome and these allergies 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 the 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 that you can sort of have a profound change the way that your body feels and is even in something as extreme as food allergy there's something really exciting about that sound spot on at zoe we never stop being curious about how people respond to food so we recently asked thousands of people about their breakfast what they eat and how they feel about it their answers may surprise you over 70 told us that their breakfast is balanced yet only 6% get enough fiber if you've been listening to this podcast you know that's not enough to be balanced and it's no wonder that only 16% felt energetic after eating clearly breakfast is broken but what if you could get a breakfast that actually supports your energy and gut health meet daily 30 our 30 plant gut supplement that's out to fix breakfast one scoop at a time daily 30 is designed by zoe gut health scientists and features 4 grams of fiber and ingredients that support gut health digestion energy immunity and skin and hair deliciously crunchy you can sprinkle it on yogurt and berries porridge avocado toast eggs even pancakes tastes great on lunches and other meals too as we've discussed repeatedly on this podcast healthy habits are easier to start in the morning so why not get your 30 plants in before 10 a.m find your breakfast fix and try the new formula at zoe.com slash daily 30 our scientists have just redesigned daily 30 to include even more plants including raspberries goji berries fermented green tea kombucha kale and marine algae by the way whenever we share what daily 30 can do UK law requires us to say that it's a natural source of calcium which supports gut health and digestion and copper which supports energy immunity and skin and hair if you tune in regularly you know what we think about this honestly we prefer to let the benefits of daily 30 speak for itself go to zoe.com slash daily 30 to get started try it for a week and see how you feel