Leah:
Welcome to the Ideal Nutrition podcast. I am Leah Higl and I’m here with my co-host Aidan Muir. And today we’re talking about how to not go about identifying food intolerances and how to actually go about doing them and identifying them. So first thing I’m going to start off with is just kind of a caveat on allergies versus intolerances. So the difference between an allergy and an intolerance is that an allergy involves some kind of immune response, whereas an intolerance does not. So we’re talking solely about intolerances today, so not allergies whatsoever.
So food intolerances cover a wide range of symptoms, so things like stomach pain, bloating, flatulence, diarrhoea, constipation, all that gut stuff. But it might also involve things like rashes and hives, mouth ulcers, maybe sometimes headaches and fatigue. So they can all be part of like food intolerance symptoms as well. So let’s start with how to not go about identifying food intolerances.
Aidan:
So the first one we’re going to start off with is blood tests or specifically, IgG testing. It’s the most common one that we probably see. I’m pretty cautious with talking about this one because as I said, it’s the most common one that we see. Like I would say about 5%, maybe a little bit less of my clients come in having already had one and I can see why. I can see why people do get it because oftentimes they have spoken to somebody who’s quite confident, quite charismatic. And it is also appealing because quite literally it is just a blood test. And five to seven days later on average, you get back a list that covers like 50 to 300 foods, like somewhere in that kind of range, telling you which foods you’re sensitive to.
And it will give like a low, moderate or high level of sensitivity is the proposed mechanism. And oftentimes, like there will be a description at the start being like, do you have any of those symptoms that like you kind of just talked about at the start? Like, do you have bloating? Do you have rashes? Do you have like a lot of that like do you have brain fog like a lot of things that like almost everybody will have like some form of symptom and everybody’s like looking for solutions as well and I wish a blood test would work because it’s easier than the other stuff it’s a lot easier the the short answer is that it’s not a validated test but like going through a little bit further it’s interesting to look at what it is.
So IgG, so immunoglobulin G is basically a memory antibody. It’s basically testing your exposure to foods. Because of that as you can imagine the false positive rate is really high because it’s not testing whether you’re sensitive to a food. It’s really just testing to see if you’ve been having that food. And that’s a bit of a catch because if you do this test and it comes back and it tells you that all of the foods you’re eating, or a lot of the foods you’re eating, are what is causing you symptoms, and then you stop eating all of the foods you’re eating, you probably are going to cut out foods you are intolerant to.
It’s just a tricky kind of case because it’s like you’re also going to cut out a lot of foods you’re not intolerant to in…
Leah:
And you probably enjoy it because you’re already eating a lot of them.
Aidan:
Yeah. And like often it’s coming back with a list like 50 plus foods and they’re like common foods. it’ll be stuff like, you can’t have wheat, can’t have dairy, you can’t have a whole bunch of random fruits. Like it’s a pretty big list. And I don’t know if what I’ve said is compelling enough and I hate appeals to authority and stuff like that, but I am going to quote the Australasian Society of Clinical Immunology and Allergy just because I feel like like, don’t know, do people just trust me when I say stuff like that? I want another outside perspective on this as well. So it’s not just you listening to me and kind of taking my word for it and everything like that.
And the quote that I’m going to go with is, IgG antibodies to food are commonly detectable in healthy adult patients and children whether food-related symptoms are present or not. There is no credible evidence that measuring IgG antibodies is useful for diagnosing food allergy or intolerance, nor that IgG antibodies cause symptoms. Somebody can have zero symptoms and get one of these tests and it’ll come back with a whole list of things they’re sensitive to, even though they don’t have symptoms. Like the whole point of this is to find out what is causing your symptoms.
As a side note, just to wrap up on that topic, there is another option called IgE testing, which is commonly done for allergies. That is a separate thing, as Leah mentioned at start, we’re talking about intolerances, and even IgE testing has some issues of accuracy, and it’s usually never done in isolation, because I have had clients who have gotten that test done, and it still shows up a lot of things that they actually don’t have issues with as well. When IgE testing is done properly, it is done with a thorough history as well, often by a doctor and everything too, but that is a separate topic to IGG, which is what we’re talking about here.
Leah:
So, IGG is definitely the most popular one I see come through my desk. I have a lot of clients that have had that done and yeah, it’s pretty much given them a list of foods they eat regularly and they’re like, damn, now I can’t eat any of this stuff. Which is super annoying, because usually it’s not their issue. But there’s also a lot of other tests that are out there that claim to identify food intolerances, but just have absolutely no scientific research
So one common one is like a hair analysis. like literally sending your hair off, getting like a DNA test done on it. That is not going to tell you what you’re intolerant to, unfortunately. Like we said with IgG testing, we wish it was that easy. Another common one would be kinesiology. So I’ve seen this quite a lot, but it’s usually naturopaths that practice this and they’re looking at the way that your body moves and like biomechanical like physiology stuff and going because your arm moves like this you must be intolerant to gluten so obviously we don’t have research backing up the fact that like that works like
It’s a bit of a, it’s a questionable one for sure. And I wouldn’t be taking anyone’s word for it based on that, unfortunately. There’s other tests like Vega tests and LCAT that use like machines to try to identify intolerances. Once again, they’re just not validated tools. So outside of lactose intolerance and something we will talk about, which is CSID, all other intolerances really do need to be diagnosed through elimation and reintroduction diet. It really comes down to needing to do that full process in order to get a gauge of your intolerances.
Aidan:
Yeah, and as we, once again, we’re talking about off air, but like we were talking about off air. About how we’ve got empathy because it’s like, I don’t know, like how are you meant to know how to identify intolerances unless you know?
Leah:
100%. And a lot of these, like we were talking about this, but a lot of these practitioners just come in so confident that they’re, and they probably have full belief that the system works as well. Just we don’t have the scientific evidence to say that it does. So obviously as evidence-based practitioners, we’re not going to use something like that.
Aidan:
Yeah, 100%. So as you mentioned, much like the way to identify intolerances, sensitivities, whatever you want to call it, is typically going to be through elimination and systematic reintroduction. But there are two or three, but I’m going to go through two kind of exceptions, one more so than the others. The first one is lactose intolerance. So technically that can be diagnosed by a hydrogen breath test, where they basically give you 25 to 50 grams of lactose, keeping in mind that one cup of milk is about 12 to 13 grams of lactose. So like the equivalent of two to four times the amount of lactose you get in a cup of milk is what you’d be tested with. And then they test your breath and see whether or not you’re lactose intolerant from that. Is there anything being malabsorbed or anything like that?
That is a useful way to do it, but not many people actually get that test. And the reason why is it is actually pretty easy to trial and error. With a lot of these other intolerances, it is more complex. With lactose, it is kind of simple if you have a cup of milk, or two cups, let’s use two cups just to make it clear cut. If you have two cups of milk and you get symptoms like bloating, gas, diarrhoea, all those kind of things, it’s probably lactose intolerance. There’s a high percentage chance. Then if you go and have a lactose-free dairy product, for example, lactose-free milk where the only difference is lactose content is broken down, it’s gonna be galactose and glucose instead of lactose, and you don’t get symptoms. Lactose is the issue.
Leah:
That’s all the testing you need.
Aidan:
That’s all the testing you need. It’s quite simple. The next one’s a little bit more complex. So fructose. So fructose malabsorption can be technically diagnosed through a breath test. And that is an accurate breath test. But it’s probably not as accurate in practice or in practical terms as what we’d like. Because one of things I said earlier is we only care about food intolerances when they cause symptoms. Does it matter if you’re intolerant to something if you never get symptoms?
Leah:
No. At the end of the day, it’s all about symptom management. It’s not like you’re malabsorbing fructose and that’s then causing disease beyond that. It’s really just about symptom management.
Aidan:
Like say if you feel great all the time, do you care if you malabsorb fructose? It doesn’t matter. basically fructose malabsorption can be diagnosed by a breath test as well, but it can be a false positive in a way. So basically one study identified that 30 to 80 % of people have incomplete absorption of 50 grams of fructose.
Tests for fructose malabsorption typically use 25 to 50 grams. So theoretically, like half the population are fructose malabsorbent. So it’s like, but half the population aren’t getting symptoms like this. Like if you look at IBS as an example, I think IBS, it’s about 13% of the population, somewhere between like seven and 14% of the population have IBS.
So like, okay, it’s clearly like on average people with fructose malabsorption aren’t getting significant IBS symptoms on average. There were individuals who will, but not everybody does. The average person consumes about 16 grams of fructose per day. Like that’s what the average seems to be. Whereas people who have really high intake get up to 60 to 100 grams per day. Keeping in mind that like a lot of people think of fructose as the sugar in fruit, but fruit typically is not just pure fructose.
it has fructose and glucose in different ratios and stuff like that. So that’s quite a lot of fructose to get up to. But the key point though is even with fructose, I’d almost ignore the fructose malabsorption test. I would just do that elimination and reintroduction style stuff that we’re gonna talk about. Probably next.
Leah:
Yeah. Let’s go straight into it. Yeah. It’s like a good segue because identifying a fructose intolerance can also be done as part of a low FODMAP diet. So the low FODMAP diet, we’ve done a couple of podcasts on its success rate in managing IBS symptoms is one of the best. like 50 to 80 % of IBS cases are significantly improved through doing the low FODMAP diet. 50 to 80% is a lot a really good success rate.
Basically it’s a kind of diet where you eliminate all FODMAPs for a certain period of time until symptoms have resolved and FODMAPs are short chain carbohydrates and sugar alcohols predominantly found in plant-based foods but it also includes lactose which is obviously in dairy as well. So you cut those out for a period of time and if symptoms resolve you go okay it’s probably FODMAP related but there’s different FODMAP groups.
So our after you’ve done the elimination phase, you go through and systematically reintroduce and test the FODMAP groups to identify exactly what your intolerances are. So it’s a pretty long process. It usually takes quite a number of weeks, but we know this is one of the best ways to manage IBS symptoms and to really identify those different intolerances.
Aidan:
Yeah, and jumping in there, one of the things, so like I saw some maps perhaps just talking earlier as I was going through, I was like, I want to see IgG testing from other. So it’s like watching a video on it. But like one of the points that they made is like oftentimes people with their style of reintroducing foods that those two natural paths happen to be talking about they mentioned that like people will reintroduce one thing and they’ll feel all right then they’ll reintroduce the next thing
kind of maybe some mild symptoms. Then the third thing, they’ll really notice symptoms and by the fourth thing, they’re feeling rubbish or back to like how they felt before they did the elimination. With this style of elimination diet that we spoke about with the low FODMAP diet and the next one I’ll talk about later as well in terms of food chemicals. But like with the low FODMAP diet, after the elimination phase, you’ll reintroduce one food.
And even if you don’t get symptoms, you take it back out and you go back to a low FODMAP diet, you do a washout phase of a couple of days, and then you add in the next food. So you’re only testing one thing at a time. And on, in this case, like day three of the testing process, you’re typically having a really large amount of that food. And it’s like, well, if you don’t get any symptoms from that food, you’re probably not going to get symptoms. And the reason you have to do that is because of this stacking effect.
Where say there’s a threshold of where you get symptoms, maybe you have one food and it doesn’t cause symptoms, but then you add another, then you add another and you add another and suddenly you’re over that threshold and you’re causing symptoms. But you would only think the last food you added causes symptoms when it’s like a cumulative effect. But going back to the low-FODMAP map diet, assuming it worked in the first place, you’re testing each food individually and you’re trying to find out what actually causes it, which gives you quite a bit of confidence that that food is the issue.
The next one we’re gonna talk about is food chemical intolerances. This is a pretty niche area and I would pretty comfortably say it’s not as well studied as FODMAPS or it’s not as well defined. So the closest thing I say we’ve got to an evidence-based approach for this that I’m aware of is the RPAH elimination diet, also known as the failsafe diet. And that one’s really heavily focused on three chemicals, so salicylates, amines, glutamates, and then a pretty long list of other stuff including things like food colours and stuff like that as well. There is actually quite a bit of overlap with the low FODMAP diet in terms of, well firstly, it helps with IBS symptoms in a lot of cases. Some big proponents of this dietary approach believe that part of why it helps is because when you go low FODMAP, you actually go low food chemical to a degree as well.
Because when we think food chemicals, we’re often thinking packaged foods. this is literally talking about like salicylates, for example, are in fruits and vegetables. Like they are in plant-based foods, they are natural chemicals. So somebody going low FODMAP and cutting out bunch of foods is indirectly cutting out a bunch of food chemicals as well. It’s a really complex topic.
Like, I think about it in the extreme form in terms of like, say somebody goes carnivore, they’ve cut out pretty much every food chemical we’re talking about here because they don’t have any packaged foods and they don’t have any plant-based foods, basically. They’re going to have these chemicals in it because they’ll talk about this concept of like, plant-based foods have chemicals in it as a self-defence mechanism and a lot of people who go carnival previously did have pretty bad symptoms, which is why they eliminated Denta. It’s like the most extreme elimination diet.
I’m not necessarily a proponent of that, but I do think like some form of elimination, for example, the IPAH elimination diet can help you identify these things without being as restrictive, even though it is quite restrictive. So similar to FODMAPS, you go low food chemical for a certain period of time, two to six weeks, somewhere along those lines, and then you systematically reintroduce things and find out what caused it. The biggest difference between FODMAPS and this, apart from the overall approach of being low food chemical, is it’s not just relevant for digestive stuff, like FODMAPS is more just specific to IBS symptoms.
Food chemicals is relevant for pretty much every food intolerance or sensitivity condition under the sun. Anything from headaches to joint pain to IBS type symptoms, it’s pretty relevant for everything. Would you use the RPAH diet mostly in situations where they have gut and non-gut related symptoms? Because that’s where I tend to use it most. Yeah, that’s how I use it. And usually I wait for pretty clear signs to use it. I’m waiting until somebody’s like, yeah, I’ve got quite bad headaches and I have digestive issues and I have a rash or like, I don’t like using it unless it’s really gonna improve somebody’s life, which I have, like there’s a lot of clients who it’s been like an absolute game changer has been so worthwhile for, but even FODMAPS is hard enough.
Like people don’t get it. Like people like imagine your family trying to cook for you, cook a meal for you and you have to tell them, on low FODMAP, like your family’s not gonna get it. But then imagine food chemicals, like no one knows what salicylates are.
Leah:
Even as like new grad dietitians only just just learning about this stuff, because we don’t, I didn’t learn about RPAH in uni, you?
Aidan:
I don’t think so, no.
Leah:
Yeah, so I didn’t learn about any of this food chemical intolerance stuff. So it’s, it’s really quite complicated. It’s not something everyone’s gonna know about, obviously.
Aidan:
Yeah. And like, obviously, when I’m saying evidence based and stuff like that, like there is a massive team of dietitians who are working on it, so like the Royal Prince Alfred Hospital, like that’s why it’s called RPAH, like they do this in their allergies unit, allergies and intolerances, I’m not really sure, but like they’re using it like in hospitals, so it is an accepted kind of approach and it is about as close to a gold standard as we can get. But yeah, it is an interesting idea.
Aidan:
Yeah, FODMAPS I use all the time. I’d say I’d only use RPAH a handful of times where it’s been quite obvious that it might help. Yeah, and usually people have pointed out triggers being like, every time I eat certain foods like this, I seem to get symptoms. And I’m like, it’s getting too obvious now. It probably is.
Leah:
Last part we’re going to talk about is CSID, so that’s congenital sucrase isomaltase deficiency. So the reason I want to talk about this is, I mean, it is under the umbrella of food intolerances, but it’s also one of those conditions where you can identify it without having to do an elimination diet. It’s one of the ways you can identify it, but you can also do it other ways. So it is a rare condition because it’s congenital, it’s usually picked up in infancy, so picked up pretty young.
Two ways you can go about identifying it. One is a low disaccharide or disaccharide free diet. So where you’re reducing your intake of sucrose, isomaltose and sometimes lactose as well, because they’re the digestive enzymes that these people are naturally lacking. So there’s a malabsorption of these sugars leading to like chronic diarrhoea, pain, like stomach pain, all these other symptoms.
Usually when it’s chronic diarrhoea, It’s picked up, like I said, in infancy when you’re first introducing solids to a baby. If they have chronic diarrhoea, that’s probably something you want to get on quick smart. So what happens is they’ll usually go in, if it’s suspected, they’ll go in for a biopsy of the small intestine and actually look at how much of these enzymes are being produced. And that is one way of identifying CSID. But you also have the disaccharide free diet, which I’ve used with some clients who have been diagnosed later in life. So it’s not a common one, but I like to mention it because it has come through my clinic quite a few times, even though it’s not common.
Aidan:
Yeah, I’ve only seen one person with that and I did go deep down the rabbit hole for that. I’m like, this is really hard to explain to somebody. Like this is really hard. Like it’s almost simpler just to go low carb. Like I don’t encourage that, but it’s just like, it’s almost simpler than just being like diacetamol free diet. it’s like, what I don’t like, like even when you say sucrose, like some people won’t know that that sugar for example.
Leah:
Yeah, I don’t know complex like an isomaltase and stuff like that. Pretty much you’re cutting out majority of grains or you’re finding a level that you can tolerate. Some people with CSID can tolerate small amounts of grains in their diet and like starchy vegetables, but some people can’t tolerate any. And most people can’t tolerate any kind of added sugars like your table sugar sucrose. But it’s one that usually has quite severe symptoms. So it’s identified early on.
Aidan:
Yeah, the last thing that I’ll probably mention is just obviously keeping an open mind. So we’ve mentioned a few things like we’ve mentioned Lactose, we’ve mentioned FODMAPs, we mentioned CSID and RPAH, but it’s also worth keeping an open mind that there’s so many like niche potential intolerances as well. One of many examples I’m going to use but like that whole A2 milk concept where it’s like they don’t have the A1 protein, they’ve only got the A2 protein. They have studies showing that even people who’ve diagnosed lactose intolerance get less symptoms when they compare regular milk containing lactose to A2 milk.
And like, I obviously see that as simple just being like, I don’t know, just have lactose free milk. But it’s like, isn’t it interesting that just by shifting the protein type, they are getting less symptoms? I’m always cautious of industry funded studies, because like the A2 milk company is the only company that’s gonna be studying this stuff. But it is just an interesting thing. And like, there’s so many little examples like that, that’s worth keeping in mind. And then there is always a case to be made for like, quite literally trial and error, listening to your body and all those kinds of things.
Like if you do not a perfect elimination, but like if you cut one thing out that you suspect is causing symptoms and you get less symptoms or significantly less symptoms and every time you reintroduce it, causes symptoms, you could arguably just cut that out. I don’t like that approach being used at a broad scale and being used on heaps of foods and everything like that. But like whenever it’s just one thing you can almost always account for it and still have a healthy diet, assuming you do account for it in some way, shape or form.
It just becomes a dangerous approach when you start cutting out heaps and heaps and heaps of things and you still don’t know what’s causing symptoms.
Leah:
Accidentally carnivore. One I think of quite a lot is non-celiac gluten sensitivity. We don’t really have a way of identifying that other than just literally cutting out gluten. Sometimes you’ll identify it as part of the low FODMAP diet because you’re out and there’s overlap between gluten and fructans and maybe it comes up there. But we know that that’s probably a thing in terms of non-celiac gluten sensitivity for some people, even though it’s more rare than a FODMAP intolerance or a fructan intolerance. It’s still part of this discussion.
Aidan:
I have a very interesting thought on that. obviously we would know that fructans, which is part of the FODMAP diet, and fructans, which is part of where it explains a large percentage of suspected non-celiac gluten sensitivity, particularly from the IBS, perspective, but from another perspective, I do wonder if a lot of people with non celiac gluten sensitivity, one way to test this and see if it’s gluten and not fructans could be seitan, because seitan is pretty much this gluten protein, right?
Leah:
Yeah, but if I believe it does have fructans in it at a pretty moderate, even small amount, so it starts to overlap again.
Aidan:
Yeah, okay.
Leah:
So I don’t know if you can actually consume a good amount of it to test without it being higher in fructans. But it’s something I have briefly looked into.
Aidan:
Yeah, because from like there are studies have been done on fructans and we’ve spoken about this previously on the podcast but like there have been studies done where they’ve given people muesli bars with gluten but no fructans and they’ve given them muesli bars with fructans but no gluten and in a large percentage of cases like more than 90% of the time fructans was the explanation but there is still that small percentage that is related to gluten and it’s like did they just randomly get symptoms or was it gluten or was it like it’s a very complex area that once again like a lot of things is pretty nuanced.
Leah:
Last part of this discussion is going to be obviously before you go down the route of identifying food intolerances, probably a good caveat to say, probably look at anything else it could be. So obviously when it comes to gut symptoms, you should be looking at things like celiac disease, inflammatory bowel disease, even bowel cancer and really ruling out any of those more severe options that it could potentially be causing your symptoms. And even things like stress, because obviously that plays a role as well. So looking at those things before going down the rabbit hole of an elimination diet would be recommended.
Aidan:
For sure, so summarising, or wrapping up, guess, so wrapping things up, this has been episode 44 of the Ideal Nutrition podcast. Normally I plug giving a rating and review, but this time I’m actually gonna plug, if you could take a screenshot and share it on your story and tag us, that would be massively appreciated. I’ve seen a lot of people do that and it does generate, like it is super helpful, so I’d massively appreciate that if people do that with this episode and any future episode too.