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Food intolerance podcast transcript

James McIntosh: Hello, I'm James McIntosh. I'm a toxicologist with safefood and this is the safefood food safety podcast series, where we look at different elements of the food chain on the island of Ireland. In today's podcast, we're going to focus on food intolerances, which are often eclipsed by concerns over food allergies, but which are probably far more common.

And here to discuss food intolerances with me today is registered dietitian and nutritionist, Sarah Keogh. For almost 20 years, Sarah has run 'Eat Well', a food and nutrition consultancy for the food industry and the public.

Sarah, you're very welcome. And I hope I have done you justice with that introduction. Perhaps you can give us an idea of your background and the work that you do.

Sarah Keogh: Thanks for having me today. As you said, I'm a registered dietitian. I've been working now for 25 years in nutrition so a couple of different areas. I've worked in some cancer nutrition, but also allows in digestive health. And you know, when we do talk about food intolerances, it's very, very often centered around gut and digestion would be the major places. I'm working there and I work with the Coeliac Society as well over the last few years.

James McIntosh: Thanks, Sarah. And just to kick off, if you go online, and you put in the search term food intolerances, sometimes you get a lot of conflicting information, a lot of people seem to be confused particularly about the difference between food intolerances and food allergy. What's the essential difference between the two?

Sarah Keogh: There's a lot of confusion there, and people do mix them up. A food allergy is where your immune system is triggered by a food. And some people obviously will have food allergies, but it's often a very quick reaction. We often think about someone who might have, for example, a peanut allergy, and within maybe minutes of eating peanuts, they are having this anaphylactic reaction, this huge immune reaction, and they might have difficulty breathing, some allergies will result in very quickly getting a rash or things like that. But what's key there is that the immune system is very much involved. And even a tiny, tiny amount of the food will cause a reaction.

With a food intolerance, the immune system really isn't involved and, people can usually tolerate a small amount of the food. If someone is for example, lactose intolerant, if they eat a lot of lactose, they're going to have a problem. But usually they can manage small amounts of lactose without having a reaction. So I suppose the big difference is with an allergy, the tiniest amount causes a big reaction, but with an intolerance, tiny amounts are usually okay.

James McIntosh: Yeah and you said that if it was an allergy the immune system is involved, I take it the immune system isn't involved, generally with food intolerance? Would that be correct?

Sarah Keogh: Not really. No, I mean, there's it's obviously an area of a little bit more research but the tests that you would usually look at for food allergy is what we call an IGE test. But as we know, at the moment, there really aren't tests as such for food intolerance.

James McIntosh: Where does coeliac disease and the non-coeliac gluten sensitivities fit into this grand scheme of things?

Sarah Keogh: The coeliac disease manages to be neither an allergy nor an intolerance. Coeliac disease is in its own little corner. It's an autoimmune disease so it's a completely different mechanism. It is a genetic autoimmune disease, but it is triggered by gluten. So technically, we would treat it like an allergy, and that even a very tiny piece of gluten will trigger the reaction of coeliac disease. But it's not actually an IGE reaction. In terms of non-coeliac gluten intolerance, that is still an area under a lot of research. So that's where people are having a reaction to gluten but coeliac disease has been absolutely ruled out and wheat allergy has been absolutely ruled out. There's a little bit of debate whether non-coeliac gluten intolerance might still be people sensitive to a thing in wheat that's called fructan. So it's a little bit trying to pull that out. But in saying that it does look like it's affecting quite a few people, and an estimated at the moment about 400,000 people in Ireland may be affected by it. But as I said, I'd still be looking at research around that for sure.

James McIntosh: Yeah, that's a lot of people. I mean, how does it compare? Do you think it's more prevalent than coeliac disease?

Sarah Keogh: Definitely. Coeliac disease is about one in 100. So we think probably 50,000 people in Ireland are coeliac, although most of them are undiagnosed, and we only have about 15,000 diagnosed coeliacs in Ireland, we're missing a few but yeah, it's a lot less than the non-coeliac gluten intolerance.

James McIntosh: What about things like irritable bowel syndrome or Crohn's disease? How do they relate to food intolerances? Or is there any relationship there?

Sarah Keogh: Yes, and no. Irritable bowel syndrome can be caused by lots and lots of different things. What we do know is that around maybe 10% to 12% of people will have some form of irritable bowel, for some it will be quite mild and others it could be quite severe and I had patients who've had to give up work with it. Irritable bowel can be related to foods and you've probably heard people talking about something called a low fodmap diet which looks at fermentable carbohydrates, which can a big issue for lots of people with irritable bowel, but other things can be relevant there as well. Things like Crohn's disease and ulcerative colitis, food concern, in particular with Crohn's disease can play a role there. And again, it's difficult to sort of filter all the bits out, we do know, I was looking at a study in children recently that if a child has a flare up of Crohn's disease, if they actually come off all food and they’re on kind of special drinks that are what we call low allergen foods, that it can actually be very good treatment, but long term it's just it's an interesting one with that, but certainly with irritable bowel yes, we would look at food intolerance there for sure.

James McIntosh: So obviously, this whole area is an area very active research, and very complicated as well, by the sounds of things.

Sarah Keogh: It really is, the more you look at it, the more complicated it gets, to be honest but you know, we should have some answers in the end.

James McIntosh: There seems to be a lot more awareness these days about food hypersensitivity in general, food allergies, food intolerances. Why is that do you think? I mean, compared to 20 years ago.

Sarah Keogh: Yeah to be honest, unfortunately, we know that the rates of food allergies are increasing. So it's something that we are hearing more and more about with that and saying that, it's still quite tiny in the numbers. But I think also people are recognizing things. For example, we know that around 10% of people in Ireland are lactose intolerant. And I think, you know, 20, 30 years ago, unless you were very unwell with it, most people sort of just didn't drink milk, and it was fine. But now people are becoming more aware of it and maybe they haven't figured out the link with the milk so some of the investigations would look at that. There's lots of speculation about are we just sort of recognizing it, in the sense that maybe people just put up with this years ago, whereas now they're saying, look, I have enough to be dealing with, and I don't need to be having all these bowel side effects while I'm at it.

James McIntosh: So in the course of your own work, what kinds of food intolerances now specifically would you come across?

Sarah Keogh: So with the coeliac society, obviously, it's gluten and lactose intolerant would be the next most common one. So about 10% of Irish people, or people living sort of North Europeans, and lack the enzyme to digest lactose. Now, it's an interesting one, because most people who are lactose intolerant can actually tolerate cheese. And they could tolerate a little bit of yogurt, but milk is definitely out. So that's quite a common one. And that's a lot of bloating, and, with kids vast amounts of gas, and maybe sometimes diarrhea, but not always.

James McIntosh: Is it mostly kids?

Sarah Keogh: No it can definitely be adults as well but you're more likely to pick it up in kids, because parents are kind of going, that's not normal, and it's usually it's the amount of gas they're kind of going and I have one child, and there is this much gas, and then I have this other child, and it's just phenomenal.

James McIntosh: That's the benchmark?

Sarah Keogh: This is it. And in adults, you do still pick it up, for sure, because, quite a few people that I've worked with over the years who came into me with irritable bowel syndrome. The problem is that they're actually lactose intolerant and that's what's been causing this irritable bowel and obviously, if you take the lactose out it works. It's just you've got to be really, really careful with that, that people don't end up dropping their calcium levels, because you know, the bowel can be nice and happy, but you don't want to give them osteoporosis later on. So striking that balance is important. But luckily, we have lactose free milk available these days, which has just been amazing. It's just been a phenomenal product that has come on for us.

James McIntosh: Isn't it fair to say that lactose intolerance depends on where you are around the world? There's some parts of the world that it's very prevalent to the adult population, but I think we're generally lucky in this world aren't we?

Sarah Keogh: We are and we've a genetic adaptation in sort of Northern Europeans to be able to tolerate lactose but you're right. If you look at like 90% of North Europeans can tolerate lactose but by the time you get to Spain, only 65% of people can tolerate lactose. And then it just sort of goes down. But what you will see is lots of countries people will still have milk, but they tend to ferment it. So if you go to India, for example, it's very rare people will drink milk, but they drink lassi, which is a fermented milk drink and the fermentation has reduced the lactose. We do see lots of dairy still being consumed but it's really North Europe where we'll actually drink milk just directly.

James McIntosh: Did you ever come across any strange food intolerances in the course of your work?

Sarah Keogh: There's some very odd ones. I always remember sometimes stress can be involved in some of them. I had a very interesting patient a long time ago who was allergic to or had a reaction an intolerance to oranges if she was eating them in a normal day, but if she was very relaxed on holidays, she could eat oranges, and they were fine. And you do actually see, now it's rare, but you will see a stress factor sometimes in some food intolerances and allergies. But there's nothing really that you would see odd. The typical ones would be fructan in wheat, and you'd be looking at a thing called GOS in beans and lentils for some people, and sorbitol for some people, which you'll find naturally in things like avocado, but also it's in sugar free chewing gums and things like that. Some people will react to those. There's a lot of things, there's nothing very odd or weird, the stress reaction is an interesting one though sometimes in allergies and intolerances.

James McIntosh: A stress-related citrus intolerance – that’s what caused it?

Sarah Keogh: Yeah pretty much and it took a little bit of figuring out. We do see at the moment as well more people being diagnosed with an exercise-induced anaphylaxis, which is someone who can eat wheat when they're not exercising but if they've gone out for a run, and then they've eaten wheat within a couple of hours, then they actually have an anaphylactic reaction, and that takes a bit of really detailed history to try and find out what's going on. How can they eat wheat here, but actually, when they've intensely exercised, they're reacting. So that’s a recent one that we've just seen in the last few years, really been picked up.

James McIntosh: That would be more of a wheat allergy side of things. Isn't that right?

Sarah Keogh: Very much an allergy than an intolerance - for sure.

James McIntosh: Yeah, that's right. And you mentioned just in passing there, fodmaps? We're hearing more and more about fodmaps and fodmap diets, and a friend of mine is actually on a fodmap diet at the moment. What’s that all about and how does this link in with everything else?

Sarah Keogh: What we have is we've all got these bacteria living in our gut and we have these components in food called fermentable carbohydrates. And if you can think of fermentation if you've ever made beer. What happens is these fermentable carbohydrates get into the digestive system, they pass on through, they get into where the bacteria are. And in most of us, when the bacteria get their hands on them, they ferment them, but they make things that are very beneficial for us. These fodmaps would actually be involved, we think in helping to prevent things like bowel cancer, so they're actually very healthy. But in some people, the reaction with the gut bacteria is really over the top. And if the gut bacteria make huge amounts, for example, of hydrogen gas out of these fodmaps, someone will get quite a lot of diarrhea, they might end up going like 15 times a day. If they make a lot of methane, they can end up with really severe constipation, which is not fixed by high fibre diets or increasing fluid, or all the usual things that should fix constipation with that. So with the fodmaps, these fermentable carbohydrates, there's a couple of different kinds. Lactose would be one of them in someone who's lactose intolerant. But we see some in other foods. So what we would look at if someone, for example, is diagnosed with irritable bowel, the first thing you're going to do is make really sure coeliac disease has been ruled out because about 15% of people with irritable bowel will turn out to be coeliac and it was missed. And the main reason it's missed is people often go off the gluten, and then they have the coeliac test. So you have to be eating gluten, when you have your coeliac test, otherwise, it doesn't work.

James McIntosh: And it’s a straightforward blood test as well?

Sarah Keogh: So it's a blood tests followed by a biopsy for adults. And yeah, but with irritable bowel, there's no blood test, unfortunately. What we do is we put them on what we call a low fodmap diet. We take these fermentable carbohydrates out of the diet. And you might do that, depending on the person between four weeks, even sometimes up to 12 weeks. And then if they get better on that, then what you do is you bring back each fodmap, one by one. And you just do it gently. And you see well what can they tolerate, you will start with a tiny amount on one day, a little bit more the next day, a really good amount the next day and if everything is good you go, okay, you're all right on that one. But if they react to it, then obviously we take that one out. So the reintroduction phase is incredibly important. I've seen lots of people over the years, and they've been on their low fodmap diet for a year and it's not good, because as I said, the fodmaps actually are important for gut health. You really want to avoid the ones you have to and make sure you bring back in the ones that you can actually tolerate because it's very important to do that.

James McIntosh: And give us some examples of these fodmap foods. What are we talking about here, we're talking about standard vegetables and fruits?

Sarah Keogh: Different ones. It depends, there's a couple of different ones. You might look at say common things that would be out on this would be wheat is usually out because of the fructan that's in it, you might look at things like avocados because of maybe sorbitol, mushrooms, because of mannitol would be another one. So cauliflower, mushrooms, avocado, sweet potato and butternut squash, they'd be things that you'd be taking out. So there's a list and apples are actually a big trigger for lots of people, which is an interesting one. And actually one of the ways you might figure out if wheat is an issue for you in terms of fodmaps is that you can tolerate brown bread, but you can’t tolerate white bread, because there's more fructan in white bread than there is in the brown bread. But as I keep saying make sure you've checked out for coeliac first with it, so there's some of the foods and it can be quite restrictive. That's why if somebody is going to do this, it's really, really important that they sit down with a registered dietitian for it. And we've a lot of research on that now and we know that people who sort of go it alone with the low fodmap diet about 20% of them will get better. But if they actually sit with a registered dietician, about 80% of them will get better. And because it's actually quite a fiddly diet to get right. But also if you're cutting out a lot of fruits, vegetables, dairy, all of that your nutrition can be really impacted. So you really have to make sure, particularly if someone's vegetarian, it’s really impacted with a low fodmap diet. You need to work with someone to make sure your nutrition is looked after as well while you're going through the elimination phase.

James McIntosh: I presume, Sarah that, as with fodmaps, diagnosis of other food intolerances really hinges on eliminating the food from the diet and then following that up with a phased introduction?

Sarah Keogh: It really is. I wish someone would come up with a blood test that actually works for it, but we haven't got one at the moment, unfortunately so it is the sort of slow and steady elimination diet with it. But it's what we always call the gold standard. And the thing is, even if there was a test, you'd still always do the challenge. Even with the fodmap diet it's actually useful after about a year to re-challenge again anyway, because sometimes the gut bacteria settle down or change. Now sometimes people have such a disruption of gut bacteria that they might actually need to have a very specific antibiotics for it. You might have heard people talk about something called SIBO, small intestinal bacterial overgrowth, which is a little bit of a different thing. And sometimes that's a breath test by a very experienced expert in order to do that. Sometimes you're looking at sort of more medical treatments for that but the fodmap diet does work there as well.

James McIntosh: That brings us on to the area of testing. How can a person tell the difference between a scientifically valid test for a food intolerance and the snake oil? I suppose anecdotally, you see a lot of adverts for food intolerance, testing in various locations, what are they based on? Are they valid? Would they give you an accurate result? Or is it a case of buyer beware?

Sarah Keogh: It’s really buyer beware, it’s definitely an area and I've spent a lot of my career having to break to people that the 200 or 300 euros they spent on these food intolerance test was an absolute waste of money. We see lots of testing with things like hair testing and various others and there's just no evidence to support them diagnosing food intolerance. The one that's been very popular was what we call IGG testing, where people send a drop of blood. But the HPRA had a statement, I think, probably 2018, really clearly calling out that these tests do not diagnose food intolerances. And what they actually tell you, which I think is interesting is they tell you what you ate in the previous three weeks. So people get a list back and it's like the red list where you had a really high result and an amber list and then a green list. But foods you've eaten in the last three weeks are going to have the highest reaction because you've eaten them in the last three weeks, they get the red. And these tests, they were around a long, long time. And I've had patients coming in with them for years. But I had to laugh over the last few years, because 20 years ago, when people came in, nobody had an avocado sensitivity, absolutely nobody. And these days, every other person comes in with an avocado sensitivity. And the big difference is nobody was eating avocados in Ireland 20 years ago, whereas now they are. And that's what I'm trying to say to people, it just tells you what you've eaten recently. And if you just keep really good food diary for three weeks, you will get the same information at a fraction of the cost. The HPRA statement actually is really worth reading on that. It's frustrating to people because they are heavily marketed and I do see lots of people saying, oh, we do food intolerance testing. And as I said, I wish there was, as a dietitian, if there was a blood test I could do rather than the elimination diet I would but sadly, no, not at the moment.

James McIntosh: Is there any truth that, you mentioned the IGG tests, that in actual fact IGG could be a marker of tolerance, as opposed to intolerance?

Sarah Keogh: Well this is it and particularly in studies on children with eczema they've looked at this and with eczema, eczema often leads to food allergies,  in a lot of people, but what they're finding is the children that have the highest IGG to a food actually are less likely to go on to develop an allergy compared to children with lower levels. The general thinking is that a high IGG reading, rather than saying you’ve a food intolerance is actually saying you are actually tolerating this food very, very well. There's a lot of confusion, I think, for people trying to figure their way through these.

James McIntosh: If somebody is worried that they may have a food intolerance, what's the first step? What should they do?

Sarah Keogh: The first thing I would look at is, have you actually got any symptoms. Because when food intolerances were really at their peak a few years ago, I used to get people coming into my clinic, and they'd come in and I'd say, Okay, what are we here for and they say I think I might have a food intolerance. And I'd say, Okay, well, what are your symptoms? And they'd say, Well, I don't have any, then I'd say well go home then. Because if you haven't got any symptoms, you haven't got food intolerance, it really is that. What you're looking at is what are your symptoms?

Very often, food intolerance is really about digestion. And I'd say pretty much 99% of people I'd see it's digestion. So if your digestion is funny, the first thing you do is you go to your GP, and you get your coeliac tests done, rule that out because it's quite common in Ireland, and it's missed a lot. So coeliac test first, and then let your GP check out and see does your GP want to send you to, do you need to have an endoscopy and colonoscopy, let your GP - don't self diagnose. And if the GP goes look, we've ruled out everything you don't have coeliac disease, you don't have Crohn's disease, you don't have any of those things you're having these symptoms.

Then your next step is a Coru registered dietitian and your Coru registered dietitian is going to be able to look at your foods and what they’ll do is take a very detailed history and that's the thing it's the skilled part of it is actually the conversation with the person and going what symptoms? When? Which foods? and just really going through it and having a look at that. And then from there, you might do the full fodmap but you might actually just do one or two because you know, you might sit and look at them and go I actually just think it's sorbitol with you and we’ll try that rather than trying to do the whole thing. It's just I suppose it's like anything else. It's just getting the professional though it. So the elimination part and then as I said, the reintroduction to make sure because I see people and they've given up dairy for all kinds of reasons maybe for sinus and for some people, that's fair enough. But someone says to me when I'm off dairy for sinus and you can hear their sinuses are still really bad. And I’m going well did it get better when you cut out the dairy? And they're like, no. I was going well you could probably put it back in again then, if you cut something out, and there's no improvement, then that wasn't the problem. But there's so much I think, online and social media and everything saying, well, you should cut this out, and you should cut that out. I was talking to a friend this morning, and she was like, well, maybe I shouldn't eat tomatoes, because you know, are they not bad for arthritis? And I was like no! But they're saying, but they're acidic and it's like, but your stomach produces litres of hydrochloric acid a day,one tomato in the middle of all of that is going to make no difference. But it's just people are bombarded. And it can be so hard to actually separate out sort of fact, from fiction.

James McIntosh: And I suppose the current celebrity culture doesn't exactly help?

Sarah Keogh: It's a little bit there and I have to say, some celebrities are wonderful and will actually go I don't know anything about this and talk to experts. But you know, someone is on a special diet and I think with celebrities, people have trust, they're a familiar face, they trust them. So they say, Well, I'm doing this, well that sounds interesting. I would always say would you trust them to do the electric replacement in your house? And they're like, No, I say, well, they have as much experience as an electrician the lot of them as they would have in terms of nutrition information. So it's hard, but I think sometimes people look at a celebrity who looks fabulous, they’re slim, their skin is great, and they go they must know what they're eating, and not saying that they don't, but we just need to be careful about, particularly when it comes to what we're cutting out of our diet, because I would have a really big concern about the amount of people cutting dairy foods out of their diets for no reason. Now if someone wants to go fully plant based or things like that, but I see people say, Oh, you know, that causes cancer, whereas as we know, the evidence shows that absolutely, it doesn't. But I'm just seeing lots of people in their 30s and under and their calcium levels are so low, I'd be really concerned about their bone later on. And they're not replacing their calcium, they think that they had three spinach leaves in their sandwich for lunch and it's covering them and it's just not.

James McIntosh: I suppose the same for a lot of the gluten based foods, correct me if I'm wrong, would be a good source of fibre dietary fibre, isn't that right?

Sarah Keogh: Some would be for sure, some of the the gluten free foods would be actually higher in fiber than the ordinary, some would be lower. They're very varied. I think if you're looking for that it's again, check labels with it. There was certainly sort of a big fad where everyone was going gluten free but you know, we did find loads of coeliacs in that because people are going well, I tried this gluten free, actually, suddenly, I was amazing and my iron levels came up and my hair stopped falling out. And we're like, okay, you're probably coeliac. So we check that, but there’s trends with different foods, and people like to do different things and play with diet, but I said, I don't mind any of that as long as you're getting all of your nutrition with whatever pattern you're following in terms food.

James McIntosh: There's no special recommendations is there with regards to food intolerances? For instance, in the same way, specifically with food allergies now, particularly in what are called susceptible families or atopic families, for instance, they'd be advised to introduce things like peanuts, from six months of age, in order to stave off the potential for developing a peanut allergy. Is there any recommendations with regard to food intolerances?

Sarah Keogh: Not to the same extent, the allergy would be a little bit different but with food intolerance, no. What you will sometimes find, if there's a couple of people in a family who's lactose intolerant, you'll generally turn up one or two more who are as well. But again, it's usually that genetically, they're just not making the lactose. That would be the only one that you might see a little more often. I'm always deeply suspicious when I see, someone comes in and says I’ve irritable bowel, and my mother has it, and my cousin has it, my sister has it and I'm kind of looking at you going, I'm going to check the whole lot of you for coeliac disease, because that's usually what's, and quite often, unfortunately, that is what it turns out to be. And as I said, coeliac disease isn't a food intolerance but we do know that it's a good idea to be kind of giving gluten from around six months anyway, for kids with that.

James McIntosh: Yeah and I think it's important to stress, as you said earlier on, that not all coeliacs are actually diagnosed. Isn't that right? One in six or something is it, might actually be diagnosed?

Sarah Keogh: Yeah we've estimated, we should have about 50,000 diagnosed, and we have around 15,000. So we're missing about 35,000 coeliacs.

James McIntosh: Which is a lot!

Sarah Keogh: It’s a lot, so if you've irritable bowel and you've never had to coeliac test, make sure you pop in your gluten for six weeks and go and get tested. It's really important to do that.

James McIntosh: Yeah. And if you if you go for a routine blood tests with your GP anyway, I mean, they can actually do the coeliac test.

Sarah Keogh: They can do it there. It's not usually a routine test, but the crucial thing is that you have to be eating gluten for six weeks beforehand, if you just go in and get it without the gluten it will just come back negative even if you are coeliac, which is very confusing.

James McIntosh: I suppose the take home message really for our listeners today, Sarah, would be if you think you have a food intolerance, don't self-diagnose, go to your GP, they will probably refer you to a dietitian or nutritionist because you certainly have to have a controlled approach to investigating what you think may be a food intolerance, isn't that right?

Sarah Keogh: And that's it. Make sure it's a Coru registered dietitian and you can check that. Dietitian is a protective term so that's what you look for with that because that makes sure that you have someone who really knows what they're doing for this and you can get in touch with the INDI,, and, and they'd have a list of dietitians that you can contact as well, but you’ve the HSE dietitians that your GP can refer you to as well.

James McIntosh: Okay, well, we’ll end there. Thanks, Sarah, for that exploration of food intolerances, which affect so many people in the island of Ireland. And thanks to you too our listeners for tuning in. If you want to get in touch by email with us, go to [email protected]. And if you want to hear more search safefood podcasts, wherever you get your podcasts or join the conversation on Twitter @safefoodnetwork and follow us on LinkedIn. Until the next time, goodbye.

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