Podcast Episode 71 Transcript – Food Chemicals and Intolerances


Hello and welcome to episode 71 of the Ideal Nutrition Podcast. My name is Aidan Muir and I’m here with my co-host, Leah Higl. Today we’re going to be talking about food chemicals and intolerances, specifically talking about the RPAH elimination diet. This is a diet we’ve both had a little bit of experience with working with clients and everything like that. It is a complex diet and it is also a complex topic. I think it’s a complex topic because it probably affects most people in some way, shape or form. It’s just how much it affects people, whether we should really worry about it and how much we should do about it.


Yeah. I mean, for the people that really should worry about it, we’re talking about people that actually get symptoms that are affecting your life in some kind of significant way. We’ll go into what these symptoms might look like, but it can be IBS-related or it can be non-gut-related as well. But at the end of the day, if you don’t have any symptoms, you shouldn’t be following this kind of food chemical elimination diet because it’s really for a very specific purpose.

You could make the argument that limiting certain food chemicals like in heavily processed food is probably beneficial for most people. But this kind of food chemical diet also does include just naturally-occurring plant chemicals, so it’s not just things like additives and preservatives that we’re trying to limit in regards to ‘food chemicals’. Yeah, if you don’t have symptoms it’s not something you have to worry about usually.


Yeah, exactly. In terms of what symptoms we’re talking about, it’s very broad. Going through a list we’ve got like IBS symptoms, headaches, hives, rashes, sinus issues, eczema, hyperactivity, fatigue and a bunch of other stuff. Part of the reason this topic’s so difficult is because almost everybody can identify having at least one of those symptoms, like what percentage of the population is fatigued?

What percentage has rashes? What percentage gets headaches regularly? What percentage gets IBS symptoms? It suddenly becomes a large percentage of the population having some form of these symptoms. I typically only go down the route of the full RPAH elimination style diet or really looking at food chemicals deeply for people of relatively severe symptoms and more so if there’s some form of linkage. Like if they say, “My symptoms get worse when I do X thing, that lines up with the RPAH elimination style approach.” Yeah.


Yeah. There has to be some kind of link there. It’s not like someone’s going to walk in and say, “I’m feeling really fatigued.” And I’m going to go, “Let’s do a food chemical intolerance elimination diet.” Yeah, that’s a big one. What chemicals are we actually referring to? There are three main food chemicals that are part of this process and that’s salicylates, amines and glutamate.

In addition to that, there’s a pretty long list of different kinds of food additives including food colors, preservatives, flavor enhancers. Generally it’s important to acknowledge that a lot of these food chemicals like salicylates, amines, glutamates are just found also naturally occurring in foods. So this food chemical elimination diet can get pretty restrictive because they’re in just so many foods.


Yeah. That’s what makes it so complex as well. Because if it was just additives, this would be a simpler topic, which I guess going through what food these are found in a little bit more deeply, additives are the easy ones. If you get packaged food that has a long list of ingredients, there’s a relatively high chance that there’ll be additives. One place I’d want to start before going through that as well is that we do have a food chemical elimination guide on our website and that has a list of all of these foods.

If you wanted to look at that, that is there. You can find that in the show notes, which is not something that we have talked about much. Have we spoken about the show-


No, I don’t think we’ve ever mentioned our show notes, but we do them for every episode.


Yeah. Hanah, who’s part of our team, she puts a lot of work into doing our show notes, so you can find show notes for every episode, but yeah, for something like this you can go to the show notes and you can find this list of these foods so that if you wanted to look at the list you can find it. There is a bunch of additives and you can look for those additives specifically on food labels.

Going through the other ones, so we’ve got salicylates. Salicylates are natural chemicals produced by plants as a bit of a defense mechanism against insects, pests, microbial attacks, those kind of things. I find salicylates the most interesting one because of like the carnivore community, how they’re always like, “Plants have these chemicals in them to defend themselves.” It does come from a grain of truth. That doesn’t make a carnivore diet the approach to go down, but there is a grain of truth to that aspect of it.

Salicylates are found in a lot of fruits, vegetables, herbs, spices, tea, coffee, beer, wine. A lot of plant-based foods have these. Amines are a little bit more complex and are found in a lot of foods such as fish, cheeses, sauces, chocolate, nuts, seeds and some alcohol as well. Glutamates are often found in fermented and extensively cooked foods as well. MSG is probably the most common example that most people will know of this.

Then it’s also about the amounts that they have as well in terms of these things will be in a lot of foods but some foods will just contain more of them than others. Salicylates are probably in almost every plant-based food, just in different amounts basically. As an annoying but simple guide, typically the stronger the flavor of the food, the higher the food chemical content as well.


Annoying for many reasons. In terms of the process that you go down when you’re following this food chemical elimination diet, if you’ve heard of the FODMAP elimination diet, it’s a very similar concept or process. The gold standard to the RPAH elimination diet is to follow a low food chemical diet for two to six weeks or until symptoms have gone away. Obviously symptoms are only going to go away if your symptoms are related to these food chemicals, but that it is quite restrictive like we said.

We’re cutting out a lot of different foods. We’re doing it for a decent amount of time. Then you systematically reintroduce these different groups of food chemicals and additives to see which ones are actually triggering your symptoms. Now, whilst I say that for most people the low FODMAP diet, you might be able to do it without a dietician, maybe, this one I would say it’s very unlikely that someone could do it without some kind of help from a professional.

It’s quite a complex one to do, so I would always recommend that. But we do have a full guide on our website that we’ll link in the show notes as well so that is available if it’s something you’re looking at. Once you do this kind of following the strict diet, reintroduction testing and you know what triggers your symptoms, you can then find out what your threshold is for those different things that trigger your symptoms and then develop this individualized approach for you that is less restrictive overall.


As another note, tolerance also changes over time as well, so even if you go through this process, it can change. That’s another thing that makes this complex as well. It’s another thing that it leads into that carnivore discussion as well. Because if somebody goes carnivore, they also go low food chemical at the same time, but tolerance changes. One of the things that a lot of the literature on this topic talks about is if you take away food chemicals, this sounds weird, but your tolerance to them also drops most likely.

When you reintroduce them, your symptoms can be higher as well. That creates another kind of… It’s almost like a self-fulfilling prophecy if somebody goes completely low food chemical that when they have to then-

That adds a layer of complexity into this as well. In terms of the next topic, we really want to talk about what is the success rate of this kind of approach and what does the research on the topic show? Basically this appears to be the best method we’ve got. It’s the closest thing to an evidence-based approach we’ve got for identifying which food chemicals are causing symptoms and how to manage it as well. But just because it’s the closest does not mean it is a perfect approach.

I think there’s still a lot of room for improvement and a lot of room for more evidence to come out in this space. There is a ton of anecdotal evidence as well. If you google, you can find it everywhere. There’s a bit of research mostly coming from the Royal Prince Alfred Hospital, so the RPAH, and a bit of this research has positive outcomes but it is still mixed. One of the biggest areas I always highlight when talking about this is I talked about MSG.

If you look at research on MSG by itself, it has never been linked to headaches in comparison to placebo. There is a ton of anecdotal evidence that it causes headaches. A lot of people will talk about it, but in the research it’s never been found when compared to a placebo. But it is incredibly common for people to report symptoms when they add it back in following the elimination diet. I don’t have an explanation, but that’s not in comparison to placebo.

We see in a lot of areas where symptoms like headaches or IBS and stuff like that, that symptoms can be caused for a variety of reasons as well.

I’m going to use an example, but creatine supplementation. If you compare creatine to placebo and you look at GI symptoms, creatine rarely increases GI symptoms. It does, but it’s incredibly rare. We’re talking a very small percentage of people noticing symptoms. If I give a client creatine-

… anecdotally, like 30 something percent of people notice symptoms and that’s where it gets really wild and that’s where I look at it that kind of perspective for headaches and MSG and stuff like that, being like we can also get a bit of a misrepresentation if we’re not comparing to placebo. On other topics, some of the research also looks particularly promising. One of the biggest examples of this I can think of is eczema.

It seems based on small sample size research, not large sample sizes, but around 75% of people with eczema show significant improvement when following a low salicylate diet. That’s-


It’s pretty huge.


… huge. Eczema is something that no single dietary approach seems to have that large of an impact, so like in terms of helping 75% people, so that’s quite huge. Obviously I’d love to see larger sample sizes and stuff like that. It also still comes alongside the challenge of is it worth it for some people?

Personally, I have a client who already has a history of disordered eating who’s been referred to me for eczema and I’ve got the challenge of being like, “Do I get them to go low salicylate when they already have issues with food flexibility? Do I make it more restrictive?”

Then it’s weighing up the pros and cons and stuff like that. Fun fact, in that case I’ve chosen not to, but it is a challenge obviously.


For sure. I think there are many downsides of this type of approach. Firstly, generally it’s hard for anyone who’s going to be following it. It’s a hard restrictive thing, but then bringing in disordered eating or a not great relationship with food, it’s probably then also just not advised to pop over the top of that. Even this study on salicylate restriction that you found, so it was a study that looked at salicylate restriction in children and they found that adverse effects occurred in 31 out of 66 children in that.

It was nutrient deficiencies, food aversions that started to develop, but also four children were reported to develop disordered eating. So maybe even if you don’t have issues with food and then you’re following this very restrictive approach, you may develop some anyway. That’s always a risk I suppose. Then if you already have issues with food on top of it, probably more of a risk for you. That is a potential downside and that’s just salicylates.

That’s not even taking into account that the food chemical elimination diet as a whole is way more restrictive than just that. Yeah, there are a lot of people that I won’t use this approach with for a multitude of reasons. I’ve also tried to, and have had some success using it with people who are vegan and who have had these kinds of symptoms, but that in itself- is tough. If you already have other restrictions that you’re working with and then you add this on top, again, that’s a huge downside to this approach.


Yeah. It’s tough enough to understand nutrition as it is. I also think people who are very black and white thinkers struggle with this. Even with FODMAPs I’ve run into issues working with certain people where I’ve talked about high FODMAP foods and they’ve been like, “Oh, I thought this was good for you.” It could be like garlic or onion and they’re like, “Oh, I thought garlic and onion were good for you.”

I’m like, “That’s not what this is about. It’s about symptoms.” This can still be good for you for all these other reasons, but cause symptoms and in this case-


Yeah, and it’s so tough going through that explanation.


It can warp I guess your thoughts around different foods in a way that’s not super helpful.


Yeah. I guess we also want to be talking about are there easier ways to do this? I have quite a few thoughts on this. The first one is you can do a modified version of this. The strict low food chemical diet is obviously very, very restrictive. As an example of how restrictive it is, when we’re looking at fruits, there is one fruit that is fitting the criteria of low food chemical or one common fruit that is fitting the criteria, and that’s pears.

It’s not even like… Yeah. It’s like if you change it to a medium food chemical approach, you’re looking at it in terms of being pears, bananas, and apples. You’ve got three types of fruit. It’s not overly exciting, but you could do a modified version of that, or alternatively you could pinpoint one group that you think might be super relevant for you.

For example, that salicylate thing we talked about with that eczema thing, it’s like well maybe we just do one of these aspects or maybe we look at first limiting those other additives and stuff like that and going for more of these unprocessed foods and stuff like that. That’s another starting point.

An interesting topic that I think about a lot with a lot of people is potentially reducing fruit and vegetable intake because that’s going to carry over to reducing salicylates and in some people that can improve symptoms. Even with like IBS symptoms and the low FODMAP diet, this is one explanation that some people have that’s like, you go low FODMAP, you likely reduce food chemicals firstly by eating less packaged food.

Secondly, you probably reduce your fruit and vegetable intake because you have less that you can have. That’s where it becomes a really complex topic in the grand scheme because we know more fruit, more vegetables very clearly leads to improved health outcomes on average in an almost linear fashion.

Then we’re just balancing it with symptoms being as like, well, ideally you go as high as you can with those things without having symptoms that seriously affect your quality of life or anything like that.


Totally. Overall, the RPAH elimination diet is an incredibly useful tool. It does a good job at identifying and managing food chemical intolerances when you have symptoms from those things but it’s absolutely not without its downsides. It’s really hard. It’s very restrictive. You have to follow it for a good portion of time.

You probably need a professional to talk you through the process, but it doesn’t mean that it’s definitely not worth using because it is useful. If it’s something you’re considering, like I said, I would probably speak to a dietician to see if it’s an avenue you should go down. But it’s good to be aware of because I feel like a lot of people are just not aware of food chemical intolerances generally.

This has been episode 71 of the Ideal Nutrition Podcast. If you could leave a rating and review that is always greatly appreciated. Otherwise, thanks for tuning in.