Professor Kari Nadeau: With food allergy, it is such a disabling disease, and it is such a disease that people have for a lifetime. And when I was training in this, I felt very compassionate towards people that had to suffer and live in fear of something that we normally do every day, which is eating.
Dr Rupy: Welcome to the Doctor's Kitchen podcast. The show about food, lifestyle, medicine, and how to improve your health today. I'm Dr Rupy, your host. I'm a medical doctor, I study nutrition, and I'm a firm believer in the power of food and lifestyle as medicine. Join me and my expert guests where we discuss the multiple determinants of what allows you to lead your best life.
Dr Rupy: Have you noticed the rapid rise in childhood food allergies? Peanuts, dairy, wheat, egg, all of these appear so commonly removed from children's diets and schools, and it's not just children that are suffering, adults are too. But is this a real phenomenon and if so, why? Well, the numbers just do not lie. Food allergy is a global phenomenon, afflicting 32 million Americans. One in 13 children in the US are diagnosed each year, and the numbers are similar for the UK. But also, one in 10 adults in both the US and UK have at least one food allergy. And this all costs 40 billion a year, and worse still, it's on the rise. But today, I'm speaking to an esteemed colleague who is at the forefront of the fight against it, and she believes that today is the beginning of the end for food allergies, and we are at the start of curing the disease for good. Professor Kari Nadeau is Professor of Medicine and Paediatrics, and for more than 30 years, she has devoted herself to understanding how environmental and genetic factors affect the risk of developing allergies and asthma and the molecular mechanisms underlying these diseases. Her research is laying the groundwork for a variety of potential future therapies to prevent and cure. In today's podcast, we talk about Professor Kari's early career and how she got interested in it, the definition of food allergy and how that differs from intolerance. I think it's really important to get our terminology correct. The environmental impact, maternal diet as well as early infancy diet with food allergy, addressing this concept of parental guilt, which is very, very common, retraining the immune system to cure food allergy, and the role of the microbiota, as well as the 6 Ds of food allergy: dryness, dirt, DNA, detergent, vitamin D, dogs, diversity. That's actually seven, but as you'll hear, Professor was in the middle of a vaccination programme in the US when we spoke, so we could only speak for a short amount of time, but it is enough, and I do highly recommend getting the book if you are interested in food allergies at all. You can find all the links on the show notes at thedoctorskitchen.com. For now, enjoy our conversation.
Dr Rupy: Kari, thank you so much for making the time to speak with me today. It's a pleasure to have you on. I know you're short on time because you're in the middle of administering vaccines today at your hospital. So I wonder before we get into the bulk of the subject that we want to chat about today, if we could touch on your career, how you got interested in food allergy, and perhaps even the story of the patient that would change your professional life going forward.
Professor Kari Nadeau: Oh, thank you. Well, it's nice to be here today. Thank you so much. And yes, we are in the middle of a pandemic and trying to vaccinate people today for the first time at Stanford, so we're very excited about that. I am so compelled and inspired by patients, and with food allergy, it is such a disabling disease, and it is such a disease that people have for a lifetime. And when I was training in this, I felt very compassionate towards people that had to suffer and live in fear of something that we normally do every day, which is eating. And to be able to think about the mind of a child and a mother and a parent having to be in anxiety about eating made me even more compelled as an immunologist and as a doctor to try to solve this problem. And what really catalysed it is a story that I was inspired by when I was in training in which a young boy who unfortunately had a milk allergy drank his sister's milk and anaphylaxed in 15 minutes. It was too late. And despite a lot of effort by the parents and by the emergency services, they were not able to revive him. And it was so sad for me. I'll never forget seeing the father shaken and crying about the loss of his son. And it seemed to me so unnecessary that any death is one death too many. No one should see their child die or suffer. And because of that, I felt like I wanted to work in this lifelong career of making sure that we can find a cure and to find the cause of food allergy to think about how to prevent and treat the disease.
Dr Rupy: Wow. Wow, I mean, and it's such a powerful story and it's something that unfortunately still happens today and I can understand that galvanised your interest in the subject and your passion for trying to find a cure for this. I wonder just for the listener, we could really set the scene of just how, what the scale of food allergy is today, because it doesn't, it never fails to amaze me how many times I do a shift in paediatrics where I work in emergency medicine and there is always at least one patient who comes in who's had a reaction and it doesn't necessarily mean it's always going to lead to a food allergy or a food intolerance, but it's definitely something that's on the rise.
Professor Kari Nadeau: Yes, it's excellent and it's excellent that you also have this experience where in the States, about one in every three minutes, someone is going to the emergency room due to a food allergic reaction. And that's too many, that's too frequent. And we need to understand why this is rising. We need to understand many areas of medicine, pandemics like COVID, epidemics like food allergy. But what we are seeing is that it's not just because people are getting better at diagnosing the disease, it's actually because the disease is indeed on the rise. And we think that's for many reasons. One is that we don't live like we used to. People that live on farms and that lived with more microbiome around them were typically less allergic. We can't put a farm in a bottle anymore. We need to understand what things we can do actively to try to prevent allergies and food allergy. One thing that's been known very well now is to diversify the diet and to add in little bits of protein simultaneously into children's diets, infants’ diets, early and often around four to six months of age, and that has been shown definitively to try to decrease the risk of food allergies. So that's fantastic. We know that knowledge now to try to prevent. In addition, dry skin is another area that's really on the rise. Eczema in London, for example, is about 50% of infants born now in London have it. And so dry skin is an entry way for allergens. And so if we can protect the skin, we can also protect the body from possible reactions like food allergy. And growing up with a dog at home, having a lot of vitamin D in your diet also helps to decrease food allergies. So we know a lot about what are the associated causes, but because of that, we also know how to change our behaviour so that we can decrease our risks.
Dr Rupy: Yeah, I mean, all that's, those points of information, I'm definitely want to come back and double click on. I wonder before we go too much further, we could distinguish what we mean by food allergy and how that differs from intolerances such that we can frame the conversation so people are really clear about exactly what we are referring to as food allergy.
Professor Kari Nadeau: That's an excellent question. So a food allergy, the way we define it, is that it's IGE mediated. That's the little molecule that I call the match that lights the fire. And it needs to dock into these cells that are allergic cells in order to work. And unfortunately, people with allergies and in food allergy, that is the molecule that mediates the disease. It's IGE. And we can test that in the blood, but it's not the only thing that can give you the definition of a food allergy. You also need to have a food challenge and skin tests to make sure that you know and your doctor knows that you actually have a food allergy. There's another category which is called food sensitivities. And with food sensitivities, you don't get an allergic reaction like hives and itchy mouth and itchy nose and itchy eyes and wheezing and blood pressure drop. That occurs with food allergy. Food sensitivities are headaches, bloating, aches. That does not happen in a food allergy. That happens in food sensitivities. Food sensitivities are annoying, but they will not cause anaphylaxis and a fatal reaction. So that's helpful to distinguish between food sensitivities and food allergies. No matter what, the person that has a food sensitivity is also suffering. It's not fun to have a food sensitivity, lactose intolerance, for example, food poisoning, for example, but importantly is it's not anaphylaxis. And so you should make sure you go to your doctor to distinguish between a food allergy and a food sensitivity. There's another group of disorders that are not necessarily mediated by this molecule IGE. And they're called non-IGE allergies. And there's a new one called eosinophilic oesophagitis that has to deal with abdominal pain and vomiting. There's another like celiac disease. That's a food sensitivity, but it's very different. It's very genetically prone. It's a sensitivity against gluten. And as you know, it can also wreak havoc on the gut, but not in a way that's consistent with anaphylaxis, more chronically. So I think that's what we talk about in the book as well is these three different main categories and how to go to your doctor and ask them questions because we do have diagnostics now in our pockets that can distinguish those three.
Dr Rupy: Absolutely. And you touched on something there that I definitely want to go into. It's it's the conversation that you have with your doctor and how the shame and guilt around food allergies can can really be distressing for for parents as well as other family members. But I just want to go back to why in your opinion and what we know about the rise of food allergies across the globe and how this is really a global pandemic rather than just something isolated to the UK and the US. You mentioned diversity of diet, but there's definitely the hygiene hypothesis. What do we know that's right and what's inconclusive about the hygiene hypothesis in particular?
Professor Kari Nadeau: Yes. So there are a lot of hypotheses and what's great about science is that we have to test those hypotheses. And that typically with a disease as complex as food allergy and allergies and asthma, it's not just one thing that's causing it. It would be nice to put your finger on it and then to solve the answers to the universe, but we just can't. And one thing that we've noticed is that there are a lot of different causes. And what we have seen is that it's not just genetics. There's a genetic tendency in some families to have allergies, but that doesn't mean that you're going to have a child with allergies. And there are many children that are born de novo with new allergies that in their family they never had it before. And so we need to get better at diagnosing it early, understanding and talking to your doctor. This is a disease that's not going to go away anytime soon. And we think that it's caused by a lot of things, but it is global, like you said, it does not see boundaries. It has established itself in any socioeconomic strata. Unfortunately, the people that are underserved and don't have access to health care have the highest risk of dying from the disease because they don't have access to epinephrine devices, but it affects all people. It's about one in 12.5 here in the US. In China, it's 8% of children. In Australia, it's even higher, it's 10%. We're seeing places that we thought because of the hygiene hypothesis, we thought, okay, well, if people live in quote unquote dirtier areas where there are a lot of parasites, like in places in South America and in Africa, we thought they were relatively protected from having food allergy, but that's not the case. We're actually seeing plenty of places now that have food allergies. And we think that's because in the evolution of detergents and the evolution of water supplies, the detergents that are in the water now, unfortunately, they they disrupt the skin. They're not really good for baby skin. In addition, a lot of food companies came out and said, let's delay the introduction of some of these foods in a well-meaning way. People thought that, not based on a lot of data, they thought that just by not giving babies a lot of different types of foods in their diet early on, that that would somehow decrease the rate of food allergy. But in fact, those countries that paid attention to those guidelines, which tends to be the UK, the US, Australia, they actually were the worst off. And in those countries that did not pay attention to those guidelines, that couldn't afford to pay attention to those guidelines, they actually had much better chances of not having food allergy on the rise in those countries. So it was quite dramatic that over the last 20 years, those guidelines that came out were actually really need to be revisited and revised. And unfortunately, they were made by well-meaning people, but they were not based on a lot of data. Now, we have a wealth of data, a wealth of thousands and thousands of children after having studied this hygiene hypothesis that it's still important to vaccinate, it's still important to live with good microbiomes in your gut, but there's more to it than that. It's more complicated and we need to get ahead of it actively and start diversifying the diet early and often in infants.
Dr Rupy: One thing that you mentioned earlier about dryness of the skin, I thought was absolutely fascinating and something that I don't think I've learned too much about. And it plays into the dual exposure hypothesis about how skin contact can can cause issues. I wonder if we could talk a little bit about that because I don't think many people have come across that hypothesis. And again, like you said, it's a hypothesis that needs testing and one that can only inform us rather than explain the whole picture.
Professor Kari Nadeau: Yes, excellent. This is a very interesting point. We noticed, and really Gideon Lack at Guy's and St Thomas's and Helen Brough at King's College, London, this is where they started to develop this. And it's not just a hypothesis anymore. Now it's actually been tested and in animal models at Harvard, they showed that if you scratch a mouse skin and then you overlay peanut dust or you paint it with a little peanut oil, that that mouse can develop peanut allergies compared to a mouse that does not have skin abrasions. And so they thought, okay, this is interesting. What's happening with children with eczema and with adults with eczema? Is it that there's enough peanut floating around in the air or in some other countries, hazelnut or other places, grass pollen, and that that small amount of protein gets into the skin and then starts an allergy. And you can think of it as, well, really is that amount of protein going to activate the allergic system in our bodies? And in a way, that's the way our body was meant to behave because evolutionarily, our skin is the first blockade against anything that is going to enter our body and being seen as a danger signal or an alarmin signal. And so when your skin is beautiful and smooth and doesn't have any damage to it, it's harder for a mosquito to get in, it's harder for a bee to bite, it's harder for a sea urchin to sting. But if they do get into the skin, we have this incredible alarmin system to make mucus and start itching and start becoming red and start trying to expel that foreign object from our skin. And it's the same thing if we eat parasites. The first thing that happens is we make a lot of mucus and we make this molecule called IGE that tries to fight the virus and we make all sorts of cells that are pretty bad actors, but eventually they try to combat the parasite, combat the mosquito, get rid of those things that aren't supposed to be on our skin. In the same way, now fast forward a million years or so, and now we still have those very prehistoric response systems through our skin. But unfortunately, they're misdirected. And that when our skin sees allergens in the air and they are activating our alarmin system through our dry skin or through skin that's broken down by detergents or by other things that are in the environment, they unfortunately cause the same signalling, itchiness, dryness, they activate the immune system to become allergic and those signals then become more tangibly sustained and then that person develops allergies and they start to become in the fabric of the immune system of that individual.
Dr Rupy: I mean, yeah, I mean, that's fascinating and the knowledge that this has been tested in animal models as well. And the fact if you paint that on top of the picture of 50% of children in urban environments like London having dry skin, it paints this picture as to why we're seeing so much allergy. On the subject of parental guilt and the impact of maternal diets and breastfeeding, you can understand the confusion across parents for whether they should be introducing peanuts or whether they should be breastfeeding and all that kind of stuff. So, and I love in your book how you definitively put the bottom line at the end of each chapter about what they should know and what has been proven. So I wonder if we could revisit that and just talk about what we know about maternal diet, postpartum diet and how that relates to food allergy.
Professor Kari Nadeau: Oh, excellent question. So yes, we try to in the book kind of just concentrate down to the key points in any chapter. I know as a parent, I get so tired and you want to do the best for your child, the best for your family. And as an adult, this book is written for adults with food allergy too, and for people that don't have food allergy, grandparents, teachers, coaches, this is such a frequent disease that I'm hoping everyone reads it. But we are trying to drill it down to help people because in the event of having a food allergic friend or child or family member or student, that we need to be compassionate and we need to understand how to deal with this. And most importantly is if you do have a child that newly developed a food allergy, it's not your fault. I want to make sure that we allay the fears because a lot of parents, we put ourselves through guilt trips and for many reasons, but this is not one of them that you should put on yourself that maternal diet doesn't seem to matter too much. What is most importantly is to eat a healthy diet, get vitamins, go to your doctor, make sure that you are following a good healthy regimen, but eating nuts in a mom's diet while she's pregnant has nothing to do with whether or not that person develops a food allergy or their child develops a food allergy. And while you're breastfeeding, it's also important to keep eating, eat healthily, but there's nothing that says that if you eat nuts or something else in pregnancy that that causes a food allergy in your child. So I want to make sure that's that allays the fears of people. And we put that in the book as little summaries of information to help people understand what's key to read so that they can move forward in the universe with these recipes in mind as to what they should worry about and what they shouldn't worry about.
Dr Rupy: Absolutely, absolutely. And I'm glad you've allayed fears in that respect because I think there is definitely a lot of confusion out there. And so the knowledge that you can have a varied and diverse diet during this period of time is is it's really, really impactful. I can't let you go without talking about the end of food allergy, which, you know, which the pharmaceutical interventions, using food as part of the pharmaceutical intervention and immunotherapy and retraining the immune system. Where are we at with treating food allergy and where do you do you feel that the field is going?
Professor Kari Nadeau: Yes, thanks for asking that question. You know, we call it the end of food allergy because I truly believe it's the beginning of the end. We're at the first domino. And what's exciting and the reason why we wrote the book in a way is not only to help the community and to help educate, but also because this is an inflection point in time where the first drug was approved by the FDA for the use in food allergy. And that was Palforzia. And it's a peanut flour pill that you slowly take small doses and build yourself up to about a peanut's worth of protein. And you need to do this in a doctor's office, you need to do this with well-trained individuals, but it delivers on the hope and promise of science. And that's what I really wanted to also make sure in the book that people understand all of this is based on science and evidence and strong facts. And with that, we need to come with the book now to help others so that that education can not only stay in an academic institution, but also made sure that it is communicated to the outside world. So with that, we also talk about therapy, the pros and cons, what you might want to choose one thing above another because there are choices, what questions to ask your doctor, is it right for you? And then we talk about the future. There are about 14 different new food allergy therapies being used right now in clinical trials. And we're doing clinical trials here at Stanford and we're really grateful for the pioneers and the patients that are in clinical trials because that really helps us get to the future and some questions and we need to make things safer and we need to use it in babies and older adults. So with that, we talk about the use of biologics and some of the really neat vaccines that are coming forward to treat food allergies. And I do believe that there will be an end. For some patients, it's now. For other people, it might be more difficult, but we now have at least the right tools to be able to create that end for many people.
Dr Rupy: That's incredible. I mean, it's it's incredible to know that there is a potential there to to treat, not only treat food allergy, but rid it. And it's it's incredible work that you're doing. One thing I did want to ask you about is um there was a mention of uh the immunotherapies plus probiotics. Um and probiotics is a massive field that I think is very much in its infancy, but it's also very misunderstood by the general public. I wonder if you could shed some light on your opinion on whether immunotherapy plus probiotics has a future and what that looks like at the moment.
Professor Kari Nadeau: Yeah, we've been, you know, really glad to see that many companies have been looking at microbiota in a natural form to help the gut maintain its good barrier, maintain its good health. And often times when that happens, you can indeed help the gut become less allergic. I don't know if microbiota will by themselves cure a food allergy, but I do know that used conjunctively with other therapeutic options, they might really help. And there are companies in Australia, a company in the US that's moving forward with this now. So time will tell the real answer to your question, but it's a great question and it's one that is answerable and one that is being tested right now. The other major area that needs to be focused on is multiple food allergies. There are so many people with more than just peanut or more than just milk. In fact, most people have more than one food allergy. And because of that, that increases their chance of anaphylaxis because they have a higher chance of accidentally ingesting something that could hurt them. And so with that, we are really focusing on multiple food allergies. There's a company now that's moving forward in with the FDA so that you can simultaneously reverse your allergic reactions to many foods at once, not just one at a time.
Dr Rupy: Great. Well, I want to be respectful of your time because I know that you're in the middle of doing a massive vaccination programme at Stanford. So thank you so much. But I'm sure we're going to have tons of questions after this pod. So if we could arrange another time where I can put those questions to you, that would be incredible. Definitely. And I'll just ask you to reiterate the 6Ds as well just before you go because I think those are brilliant and they're super memorable as well.
Professor Kari Nadeau: Oh, well, that's great. Yes, it is helpful to know about the 6Ds. And because we've done a lot of work as well as many other people around the globe to find out what's causing these food allergies and now to potentially reverse them or to prevent them. So the first D is the diversity of diet. The second D is dry skin, making sure that you use good emollients to protect your skin and the baby's skin. The third D is vitamin D, getting enough vitamin D levels that could protect you against allergies. The fourth D is dirt, having good dirt and making sure that you have good microbiome. And that's where you really have to talk to your doctor as to what fermented foods are best to eat. The next D is if you can and if you don't have allergies to a dog, if you can grow up with a dog in your first year of life, that really does protect you. Many people have found this around the globe and it decreases your risk of not just food allergies, but also asthma. As long as you don't have a food allergy. And I know that's hard to prescribe a dog to all families, but it is helpful. And the last D is DNA, that we know that it's not just about DNA, that people think it's all familial and heritage, but it's actually not that there's it's more complicated than that. So thank you for asking me to repeat those. I hope that's helpful.
Dr Rupy: Those are super helpful. And I just got a puppy actually, and I can tell you what, it's uh it's as much a benefit to my microbes as it is for my emotional health. It's amazing having a dog. So I can highly recommend it. Well, thanks again so much, Professor. I hope I'll be speaking to you very soon and good luck with the efforts today.
Professor Kari Nadeau: Good. Thank you. Have a good day.
Dr Rupy: No worries. Take care. Bye now.
Dr Rupy: Thanks so much to Professor Kari Nadeau, Professor of Medicine and Paediatrics. And I highly recommend you get the book. It is a great whistle-stop tour in the potential mechanisms behind the conditions, as well as a really hopeful look into the future as how we can use food and medicine to hopefully eradicate these issues. This is a very complex topic and I think it's going to go beyond that, but it's a fantastic start and a glimpse into what we could be looking at in the next few years. Thanks for listening to the podcast. I will see you here next time.
