Podcast Episode 44 Transcript – How and How Not to Identify Food Intolerances (FODMAPs, RPAH, Food Intolerances)

Leah Higl

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. First thing I’m going to start off with is just kind of a caveat on allergies versus [00:00:30] intolerances. The difference between an allergy and an intolerance is that an allergy involves some kind of immune response, whereas an intolerance does not. We’re talking solely about intolerances today, so not allergies whatsoever.

Food intolerances cover a wide range of symptoms, so things like stomach pain, bloating, flatulence, diarrhea, constipation, all that gut stuff. But it might also involve things [00:01:00] like rashes and hives, mouth ulcers, maybe sometimes headaches and fatigue. They can all be part of food intolerance symptoms as well.

So let’s start with how to not go about identifying food intolerances.

Aidan Muir

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 of talking about this one, because as I said, it’s [00:01:30] the most common one that we see. 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 50 to 300 foods, somewhere in that kind of range, telling you which foods you are sensitive [00:02:00] to. And it will give a low, moderate or high level of sensitivity is the proposed mechanism.

And oftentimes, there will be a description at the start being like, do you have any of those symptoms that you kind of just talked about at the start. Like, do you have bloating? Do you have rashes? Do you have a lot of things that … Do you have brain fog? A lot of things that almost everybody will have some form of symptom, and everybody’s looking for solutions as well. And I wish a blood test would work because it’s easier than the other [inaudible 00:02:28].

Leah Higl

It is so simple.

Aidan Muir

It’s a lot easier. [00:02:30] The short answer is that it’s not a validated test. But going through it a little bit further, it’s interesting to look at what it is. So IgG, 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 are sensitive to a food. [00:03:00] 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 your 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 you’re also going to cut out a lot of foods you’re not intolerant to in the process.

Leah Higl

And that you probably enjoy because you’re already eating a [00:03:30] lot of them.

Aidan Muir

Yeah. And often, it’s coming back with a list of 50 plus foods, and they’re common foods. It’ll be stuff like, you can’t have wheat. You can’t have dairy [inaudible 00:03:39] and a whole bunch of random fruits. 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, I don’t know. Do people just trust me when I say stuff? I [00:04:00] 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 [00:04:30] of these tests, and it will come back with a whole list of things they’re sensitive to, even though they don’t have symptoms. 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 the 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 [00:05:00] 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 Higl

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 [00:05:30] also a lot of other tests that are out there that claim to identify food intolerances, but just have absolutely no scientific research backing them up. One common one is a hair analysis, so literally sending your hair off, getting a DNA test done on it. That is not going to tell you what you are intolerant to, unfortunately. Like we said with IgG testing, we wish it was that easy.

Another common one would be [00:06:00] kinesiology. 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 biomechanical physiology stuff and going, “Oh, because your arm moves like this, you must be intolerant to gluten.” Obviously, we don’t have research backing up the fact that that works. It’s a questionable [00:06:30] one for sure, and I wouldn’t be taking anyone’s word for it based on that, unfortunately.

There’s other tests like Vega test and Alcat that use 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 an elimination and reintroduction diet. [00:07:00] It really comes down to needing to do that full process in order to get a valid gauge of your intolerances.

Aidan Muir

Yeah. And as we once again were talking about off air, but we were talking off air about how we’ve got empathy because it’s like … I don’t know. How are you meant to know how to identify intolerances unless you know?

Leah Higl

100%. And we were talking about this, but a lot of these practitioners just come in so confident that [inaudible 00:07:26], and they probably have full belief that their system works as [00:07:30] well. Just we don’t have the scientific evidence to say that it does. So obviously, as evidence based practitioners, we’re not going use something like that.

Aidan Muir

Yeah. 100%. So as you mentioned, pretty much 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, I’m going to go through exceptions, one more so than the other. The first one is lactose intolerance. [00:08:00] Technically, that can be diagnosed by 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 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 are lactose intolerant from that. Is there anything malabsorbed or anything like that?

That is a useful way to do it, but not many people actually get that test. [00:08:30] 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, diarrhea, 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 [00:09:00] milk where the only difference is lactose content, it’s broken down, and it’s going to be galactose and glucose instead of lactose, and you don’t get symptoms, lactose is the issue.

Leah Higl

That’s all the testing you need.

Aidan Muir

That’s all the testing you need. It’s quite simple. The next one’s a little bit more complex, fructose. 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 [00:09:30] one of the 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 Higl

No. At the end of the day, it’s all about symptom management.

It’s not like you are malabsorbing fructose and that’s then causing disease beyond that. It’s really just about symptom management.

Aidan Muir

Like I say, if you feel great all the time, do you care if you malabsorb fructose? It doesn’t matter. And basically, fructose malabsorption can be diagnosed by a breath test as well, but it can be a false [00:10:00] positive in a way. 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 have fructose malabsorption. But half the population aren’t getting symptoms like this.

If you look at IBS as an example, I think IBS it’s about 13% of the population. [00:10:30] Somewhere between 7% and 14% of the population have IBS. So okay, clearly on average, people with fructose malabsorption aren’t getting significant IBS symptoms on average. There are individuals who will, but not everybody does. The average person consumes about 16 grams of fructose per day. That’s what the average seems to be, whereas people who have really high intakes get up to 60 to grams per day. Keeping in mind that 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 [00:11:00] 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 going to talk about probably next [inaudible 00:11:16].

Leah Higl

Let’s go straight into it. It’s a good segue way because identifying a fructose intolerance can also be done as part of a low FODMAP diet. The low FODMAP diet, we’ve done a couple of podcasts on. Its success rate in managing [00:11:30] IBS symptoms is one of the best. So 50% to 80% of IBS cases are significantly improved through doing the low FODMAP diet. 50% to 80% is a lot, so that’s 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. [00:12:00] 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 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 [00:12:30] this is one of the best ways to manage IBS symptoms and to really identify those different intolerances.

Aidan Muir

Yeah. And jumping in there, one of the things. Like I saw some naturopaths just talking earlier as I was going through. I was like, I want to see IgG testing from another perspective, so I was watching a video on it. But one of the points that they made is oftentimes, people with their style of reintroducing foods that those two naturopaths happened to be talking about, they mentioned that 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 [00:13:00] the third thing, they’ll really notice symptoms. And by the fourth thing, they’re feeling rubbish or back to 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 that I’ll talk about later as well in terms of food chemicals. But with the low FODMAP diet, after the elimination phase, you will reintroduce one food. And even if you don’t get symptoms, you take it back out, and you go back to the 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. [00:13:30] 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.

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 caused the symptoms, when it’s like a cumulative effect. By going back [00:14:00] to the low FODMAP 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 going to 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. The closest thing I say that we’ve got to an evidence based approach for this that [00:14:30] 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, glutamate, and then a pretty long list of other stuff, including things like food colors and stuff like that as well.

There is actually quite a bit of overlap with the low FODMAP diet in terms of, firstly, it helps with IBS symptoms in a lot of cases. Some big proponents of this dietary approach believe that part [00:15:00] 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 are often thinking packaged foods. But this is literally talking about , like salicylates, for example, are in fruits and vegetables. They are in plant-based foods. They are natural chemicals. So somebody going low FODMAP and cutting out a bunch of fruits is indirectly cutting out a bunch of food chemicals as well.

It’s a really complex topic. I [00:15:30] think about it in the extreme form in terms of, 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 those chemicals in there. They’ll talk about this concept of plant-based foods have chemicals in it as a self defense mechanism, and a lot of people who go carnivore previously did have pretty bad symptoms, which is why they eliminated [inaudible 00:15:58]. It’s like the most extreme elimination diet. [00:16:00] Whereas I’m not necessarily a proponent of that, but I do think some form of elimination, for example, the RPAH elimination diet, can help you identify these things without being as restrictive, even though 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. FODMAPs [00:16:30] 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.

Leah Higl

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.

Aidan Muir

Yeah. That’s how I use it. And usually I wait for pretty clear signs [00:17:00] 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.” I don’t like using it unless it’s really going to improve somebody’s life, which I have. There’s a lot of clients who it’s been an absolute game changer, it’s been so worthwhile for. But even FODMAPs is hard enough. People don’t get it. Imagine your family trying to cook for you, cook a meal for you, and you have to tell them, “I’m low FODMAP.” Your family’s not going to [00:17:30] get it. But then imagine food chemicals. No one knows what salicylates are.

Leah Higl

Even new grad dieticians are only just learning about this stuff, because I didn’t learn about RPAH in uni. Did you?

Aidan Muir

I don’t think so. No.

Leah Higl

Yeah. I didn’t learn about any of this food chemical intolerance stuff, so it’s really quite complicated. It’s not something everyone’s going to know about, obviously.

Aidan Muir

Yeah. And obviously, when I’m saying evidence based and stuff like that, there is a massive team [00:18:00] of dieticians who are working on it, like the Royal Prince Alfred Hospital. That’s why it’s called RPAH. They do this in their allergies unit, allergies and intolerances. I’m not really sure. But they’re using it in hospital, 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.

Leah Higl

Yeah. FODMAPs I use all the time. I’d say I’ve only used RPAH a handful of times where it’s been quite obvious that it might help.

Aidan Muir

Yeah. Yeah. And usually people have pointed [00:18:30] out triggers being like, “Oh, every time I eat certain foods like this, I seem to get symptoms.” And I’m like, “Oh, it’s getting too obvious now. I can probably use this.”

Leah Higl

Probably [inaudible 00:18:37]. Yeah. Last part we’re going to talk about is CSID. That’s congenital sucrase-isomaltase deficiency. The reason I want to talk about this is 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 [00:19:00] ways you can identify it, but you can also do it other ways.

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 are 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, [00:19:30] leading to chronic diarrhea, pain. It’s stomach pain, all these other symptoms.

Usually when it’s chronic diarrhea, it’s picked up, like I said, in infancy, when you’re first introducing solids to a baby. If they have chronic diarrhea, that’s probably something you want to get on quick [inaudible 00:19:47]. So what happens is 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 [00:20:00] 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 Muir

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. This is really hard. It’s almost simpler just to go low carb. I don’t encourage that, but it’s just like

[00:20:30] It’s almost simpler, rather than just being like, disaccharide free diet, because it’s like, well, what are di… Like even when you say sucrose, some people won’t know that’s sugar, for example.

Yeah. I don’t know. Complex, like isomaltase and stuff like that.

Leah Higl

Pretty much, you’re cutting out a 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 starchy vegetables, but some people can’t tolerate any. And most people can’t tolerate any kind of added sugars like [00:21:00] your table sugar, sucrose. But it’s one that usually has quite severe symptoms, so it’s identified early on.

Aidan Muir

Yeah. The last thing that I will 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 niche potential intolerances as well. One of many examples I want [00:21:30] to use, but that whole A2 milk kind of concept, where they don’t have the A1 protein. They’ve only got the A2 protein. They have studies showing that even people with diagnosed lactose intolerance get less symptoms when they compare regular milk containing lactose to A2 milk. And I obviously see that as simple, just being like, “I’m going to just have lactose free milk.” But 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 the A2 milk company is the only [00:22:00] company that’s going to be studying this stuff. But it is just an interesting thing. And there are so many little examples like that, that it’s worth keeping an open mind. And then there is always a case to be made for quite literally trial and error, listening to your body, and all those kind of things. Like if you do, not a perfect elimination, but 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 [00:22:30] a broad scale and being used on heaps of foods and everything like that. But 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 your symptoms.

Leah Higl

And you’re accidentally carnivore.

Leah Higl

One I think of quite a lot is non-celiac gluten sensitivity, where we don’t really have a way of, I guess, identifying that other than just literally cutting out gluten. [00:23:00] Sometimes you’ll identify it as part of the low FODMAP diet because you’re cutting out fructans, and there’s overlap between gluten and fructans, and maybe it comes up there. But we know 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 Muir

I have a very interesting thought on that. So obviously, we would know that fructans, which is part of the FODMAP diet and fructans, which is part of what explains [00:23:30] 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 who have 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 the gluten protein. Right?

Leah Higl

Yeah. But I believe it does have fructans in it at a pretty moderate, even small amount. So it starts to overlap again.

So I don’t know if you can actually consume a good amount [00:24:00] of it to test without it being higher in fructans. But it’s something I have briefly looked into. Yeah.

Aidan Muir

Yeah, because there are studies that have been done on fructans, and we’ve spoken about this previously on the podcast. But 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? It’s a very complex area that once again, like [00:24:30] a lot of things, is pretty nuanced.

Leah Higl

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 could potentially be causing your symptoms, [00:25:00] 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 Muir

For sure. So summarizing, or wrapping up, I 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 going to 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 other people do that, and it does generate. [00:25:30] It is super helpful, so I’d massively appreciate that if people do that with this episode and any future episode too.