Hello, and welcome to Zoe Shorts, the bite-size podcast where we discuss one topic around science and nutrition. I'm Jonathan Wolf, and today I'm joined by Dr. Will Bullswitch. And today's subject is FODMAP diets.

Jonathan, we're advised to follow all sorts of diets, going dairy-free, gluten-free, avoiding fructose from fruit or cutting out whole grains or legumes. But most people don't realize is these are all variations of low FODMAP diets.

So Will, what I want to know is, what does FODMAP even mean? It sounds super geeky.

Well, FODMAP, Jonathan, is an acronym. And I'll tell you what it stands for in a second. And we'll learn why FODMAPs are incredibly important for digestive health.

Okay, let's dig into all of this then and try to map out our way to FODMAPs for our listeners. So Will, you mentioned that FODMAP is an acronym, and that tells me that there are probably a few members of this FODMAP gang. So you can tell me who's in the gang, when do they first get together? Is the gang still together? Can I join?

You make it sound so cool, Jonathan. I don't want to disappoint you, but unfortunately, I don't think you can join because it's a rather exclusive club. And also you're not a carbohydrate.

I get told often that I can't join because it's an exclusive club. Not so often that it's because I'm not a carbohydrate. I have quite a lot of carbohydrate in me. That's not enough.

Sadly, Jonathan, you and I, neither of us would be able to join this club. I don't think any of our listeners would either because none of us are actually exclusively carbohydrates. But nonetheless, the members of this exclusive gang are—I just want to prepare everyone because I'm about to use some insanely large words here, fermentable oligosaccharides, disaccharides, monosaccharides, and polials, which is basically an extremely nerdy way of describing food that contains fermentable carbohydrates. Whether they be simple sugars or sugar alcohols or short chains of sugars that actually resemble fiber, the FODMAP gang essentially got together in the early 2000s when a group of scientists in Australia at Monash University first identified them and realized that there's a huge group of people that are struggling to digest these nutrients.

Okay, so now you've explained that FODMAPs have just become more of a mouthful wheel, and it still sounds very scientific. Can you try and make it even simpler? What does this actually mean for my day-to-day eating?

Absolutely, Jonathan. Let's put it this way in terms that anyone will understand. There's five categories of FODMAPs. I'm going to run through these and you're going to be hearing food that you probably are consuming on a daily basis. The first is fructose, which is a sugar classically found in fruit, like watermelon, peaches, nectarines, apples, pears. The second is lactose. Many people have heard of lactose. That's because you'll find it in dairy products. Third are the galactans. These are found in legumes, so things like beans and lentils and peas.

This is the first one I was like, It sounds more like it's science fiction than something in the food. I know we're moving outside of the normal range. Keep going, Will.

You hear it go bean-free, but maybe this is what we're talking about. And the same could be, Oh, we'll go gluten-free. And that brings us to this next category, which are the fruitans, which you and I have discussed on a prior episode about lectins. Now, these fruitans, they're found in onions, garlic, but also the grains that contain gluten, so wheat, barley, and rye. And then the fifth group are the polials, and these are sugar alcohols that you may find in some plant-based foods, but you can also find them in artificial sweeteners.

All right, Will, so you're starting to explain that there are these five categories of FODMAPs. That's starting to get a little clearer, but it still seems like a really wide mix of foods. I don't know, like an apple and an onion and a bean. These things are very different things. Can you explain why they're lumped together? And you mentioned they could be tough to digest? Why is that?

I think it's understandable that to the untrained eye, these may feel like very functionally different foods, but yet they are tied together by the presence of these FODMAPs. The reason why it's important is because FODMAPs, the way that they behave, what I'm about to describe, you can find as being universal to all of them, which is that FODMAPs require digestion. They have to be processed. Until they're processed, until we actually digest them, they're just not well absorbed in the gut. They're able to slowly pass through the intestines. And as they do that, they're pulling water in. Now, you can imagine if you pull a lot of water into the intestines, this is how you ultimately generate diarrhea. But the other thing is that FODMAPs, I mentioned earlier, are fermentable. So what this means is that if they're undigested, they eventually will reach the large intestine. And this is where our microbiome lives. And these gut microbes will actually go to work and ferment the FODMAPs, which is gas-producing.

And so normally we talk about food for our microbes being great, so why can this be a bad thing?

The fact that they're tough to digest, this can be an issue for people that have digestive problems or gastrointestinal problems. So as they pass through and they're pulling in this water and they're producing more gas, this is how we ultimately develop symptoms and they can cause the bowel wall to stretch and create the things that we think about with irritable bowel syndrome. So abdominal pain, gas and bloating, distension, diarrhea, and in some cases, even constipation.

So, Will, this is all making the FODMAP gang sound rather like the bad guys. I'm not quite as excited to join them as I was at the beginning. However, our team here at Zoe have looked into the science and there is research that shows that people following a low FODMAP diet actually had a significant reduction in healthy gut microbes, which we would normally say is a bad things. So in other words, being on a low FODMAP diet doesn't seem to be great, but I guess there must be some benefits if some people are being told they should be doing this.

I think this is a really important point, and I'm glad that you brought this up. A low FODMAP diet is only necessary for people who suffer with gastrointestinal issues. So, for example, my diet could be described as high in FODMAPs. I actually seek them out. I want them. I want all the FODMAPs. If you're offering FODMAPs, I will take them. I am more than happy to have them. There's a couple of reasons for this. First of all, FODMAPs themselves, they aren't inherently bad. When we mentioned the gang in the beginning, I support this gang, and we'll get into the reasons why. But the other thing that I want everyone to know is that these FODMAPs, they actually have proven to be prebiotic, which means that they're beneficial to your gut microbiome. And the other thing is that FODMAPs aren't the only thing that you will find in high FODMAP foods.

I knew you wanted to be part of this gang, Will. Just like me, I was confident about it. So you're saying that as well as FODMAPs as other things in these foods, what are they?

We tend to fixate on what is the one nutrient that we're talking about. But hold up. Let's see the big picture here. High-fodmap foods include whole grains and legumes and fruit. These are incredibly healthy foods because they contain fiber and polyphenols and phytochemicals and vitamins and minerals and things that nourish our body and also nourish our gut microbes. These foods are great for our gut. I would call them gut superfoods, to be completely honest with you. Now, you mentioned a moment ago, and I said this is an important point, a low FODMAP diet reduces healthy gut microbes. Let's come at this from the opposite perspective for a moment, Jonathan. What happens when people consume a high FODMAP diet? Here's what happens. You develop a gut microbiome that has a greater diversity. This is not the perfect measure of gut health, but it is a measure of better gut health. It also has been shown to increase a family of bacteria called bifidobacteria. Now, these bifidobacteria, they are beneficial to us. They have a myriad of health benefits that include suppressing unhealthy microbes and optimizing our immune system. We want more. This is why, Jonathan, I'm all about the FODMAPs.

Give me all of the FADMAPs. I'll take all of them.

Given this, Will, why might some people want to restrict or avoid FODMAPs?

Well, Jonathan, the researchers from Monash University who coined the acronym FODMAP, they found that by restricting the amount of FODMAPs in the diet, they could actually make people feel better if they had irritable bowel syndrome or if they had inflammatory bowel diseases like Crohn's disease.

Basically what you're saying is FODMAP diet is really for people who have these digestive problems. Can you tell us a bit about what a low FODMAP diet really entails?

Definitely. It's important to understand a low FODMAP diet is not a person, perhaps even your medical doctor, handing you a sheet of paper with a list of foods that are high in FODMAPs and then you eliminating those foods. That is not what a low FODMAP diet is. Let's break this down. We know that these high FODMAP foods are actually quite nutritious for us. There's no need to change your intake of FODMAPs if you haven't been diagnosed with a digestive problem. As I mentioned, they can be full of nutrients, and many of us can eat loads of FODMAPs and be just fine. However, for those of us with digestive problems, the low FODMAP diet could be part of the solution. It's just that it can be quite tricky at first.

Why is it tricky, Will?

The first stage is very restrictive. In essence, it involves cutting back on the high FODMAP foods. In other words, eliminating them. You're going to do this for a period of 2-6 weeks, whereby eliminating these high FODMAP foods, the intention is to see an improvement in your symptoms.

I've actually done this, Will, and it's incredibly hard. If I remember rightly, I was basically eating white rice and chicken for three meals a day, which becomes pretty... It's not much fun even by meal two. It's pretty miserable. So what happens in the next stage after you've gone into that period where hopefully you see your symptoms go away?

I'm really glad that you brought that up, Jonathan, and shared your experience. So once your gastrointestinal issues stabilize, then the next step is to start to reintroduce these FODMAP foods that you have already cut out of your diet. And this is done in a systematic fashion. So you go one by one, where by doing this one at a time, you are able to identify which specific FODMAPs among those five categories, which specific ones trigger your symptoms. So most people don't struggle with all of the FODMAPs. This is not an all or nothing thing. This is a personalized thing like so much else in nutrition. And there are specific FODMAPs that a person will struggle with. So by going through this process, you can actually understand yourself, your own body, your own microbiome, and how it responds to these individualized FODMAPs. And once you build this understanding, you can narrow down the list of which ones are the problem.

And so the FODMAP diet is a trial and error process. So you see what foods are having this negative impact and which ones don't have any, they're just fine, and then you're good to go?

You could say it that way. Once you've worked out which foods are causing these negative side effects, these digestive symptoms, then you can start to move towards personalizing your own diet. What that means is that the well-tolerated FODMAPs are back on the menu. You bring them back in and reintroduce them into your diet because you know that you can tolerate them. Now, what do we do with the ones that are the problem? Well, the surprise is this is not about elimination. This is certainly not about permanent elimination. This is about moderation. These foods are good for us. Remember, they include a lot of important nutrients for us. We don't want to permanently eliminate them. What we do is we restrict them to a level that we can actually tolerate. This is something that each of us is capable of. You can tolerate these foods. It's just that we have to moderate. This is why we're using the word moderate portion size.

Will, what foods am I likely to be eating if I am ending up on this low FODMAP diet?

You start by acknowledging that FODMAPs are carbohydrates. They are classically in carbohydrate containing foods, although not in all cases. For example, dairy, this is the only carbohydrate that you will find in dairy products. By following a low FODMAP diet, in a way, you are aiming to consume more foods that are low in carbs. This could be more meats, fish, eggs, or there's some that are dairy products that you're able to actually consume because they don't have a lot of this lactose. Certain cheeses, the fermentation process actually digests and pre-processes the lactose. So bre, and chatter, and feta, and then non-dairy milk, like almond milk. Then there are certain grains. I mentioned wheat, barley, and rye are high in FODMAPs, but then there's grains that are low in FODMAPs: rice, quinoa, oats. There's vegetables that are a fair game on a low FODMAP diet. So like eggplant or, as you would say, aubergine, potatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, tomatoes, cucumber, cucumber, cucumber, or as once again, you would say in the UK, Jonathan, courgette. Fruits as well that may contain fructose like grapes and oranges, strawberries, blueberries, pineapple. You can consume quite a wide range of foods.

There are still a lot of choices on a low FODMAP diet. We just have to be conscious of it.

What are the warnings around this diet, Will?

It's very important to understand that this is not designed for weight loss. There are studies that suggest that weight loss can be an unintended consequence of low FODMAP diets. This is something that we see anytime a person enters into a hyper restrictive dietary pattern. When you enter into that pattern because of the restriction, you will lose weight in the beginning. But this can have consequences. This can compromise the intake of specific nutrients such as fiber, iron, calcium. We mentioned earlier that people who remain on a low FODMAP diet permanently, it affects their microbiome in a negative way. So for people who have the goal of losing weight, there certainly are better ways to accomplish this without having to subject yourself to a very restrictive dietary pattern like the low FODMAP diet.

I'd like to share something exciting. Back in March 2022, we started this podcast to uncover how the latest research can help us live longer and healthier lives. We've spoken to leading scientists around the world doing amazing research, and across hundreds of hours of conversations, they've revealed key insights that can help you to improve your health. If you don't have hundreds of hours to spare, no need to worry. At the request of many of you, our team has created a guide that contains 10 of the most impactful discoveries from the podcast that you can apply to your life. And you can get it for free. Simply go to zoe. Com/freeguide or click the link in the show notes and do let me know what you think of it. Okay, back to the show. So, Will, I think we got a really great picture of the FODMAP gang and how you might approach this. Before we get to your verdict, I'd actually love to share my own experiences and get your thoughts, because it's very rare that I actually get a chance to do that, Will, instead of just asking you as an interested party. But as I said, I have actually done this, and I think as regular listeners on the show know I got a lot of food intolerances in my early 20s after I was sick that got better.

At that point, that was before anybody had even heard of Fobmaps. But then I investigated this again about a decade ago, a little bit before Zoe started, and someone suggested the Fobmap diet, and I had a gastroenterologist who was also involved. And so I did this. And I think I had a couple of experiences. The first is it was really hard to do, partly just living on the restriction, because, as you said, it's not just the couple of weeks, then you're putting these things in one after another. It's slow. You've got this very restricted diet. I actually met my wife, Justine, at about this point, and I was really low energy and she was basically convinced I was starving myself. And I think that it's interesting you talk about people on weight loss. I suspect in retrospect, it's hard to get enough calories potentially just to give you all the energy because you can't eat anything and what you can eat is so boring, so you're not very excited. I think the other thing is it's very hard to do this experiment on yourself trying to understand really for these individual foods, because it's not like just with one thing, like you sometimes talk about gluten, there's all these foods, and trying to understand what's going on can be very hard, particularly if you have some symptoms, but they may be driven by the amount of things and combinations.

So it's actually very difficult to do. But I did definitely come out of this saying, Oh, I think there's some things that are really triggering this. And so I cut back on that, but then introduced lots of these FODMATs back because just as you said, the gastroenterologist and nutritional explained, you lose a lot of all the nutrients you get in food if you don't put this in. But the other thing I've taken away, because this was now probably... This was before the start of Zoe, is at that time, there were lots of foods that I couldn't eat. And today I can eat all of those foods, which is amazing. I know you went through a bit of... Having read your book, you went through a bit of this experience also over the last 15 years, where, in a sense, your gut was really not in good shape. So you would eat these foods, I don't know, cauliflower and raw onions or whatever, and you really struggle with them. But the truth is, that's a sign of, I think, the state of your gut and your microbiome and all the rest of it. And although you can't just instantly switch this on, I've definitely experienced that step-by-step, and a lot of this has been through the Zoe experience and the guidance that I am now able like you to eat a very high FODMAP diet and seek it out and feel great about how it makes me feel.

I know if I just tried to eat that diet a decade ago, I would be feeling really sick.

I mean, you brought up so many great points. Part of it is that the journey is a multi-year journey. Sometimes we are looking for short-term results and seeing that big picture, understanding that it does take time. But also there should be optimism that your gut is adaptable, that your gut can learn to consume and enjoy these foods. You are not rigidly stuck in a position where the food that you struggle with, you are completely incapable of consuming. It can be trained and the foods that you feel like you have to moderate in the future, they could be enjoyed without restriction. You're absolutely right. When I say that I want the high FODMAP diet, when I want all those high FODMAP foods, and I didn't feel that way 15 years ago. I felt the opposite. This is part of the paradox that exists is that these foods are in fact good for the gut. There is no doubt that these foods are good for the gut microbiome. But it is completely understandable that the person who suffers with digestive symptoms like irritable bowel syndrome, that they struggle with these foods and they think that these foods are the problem and therefore should be permanently eliminated.

What we're here to say is that you don't need to permanently eliminate these foods, but there is a process that you can follow to work these foods back into your diet so that you can enjoy them without restriction and actually get the nutritional benefits in addition to the flavor profiles that they bring, which is an added thing that I like. I think that there's a lot that's good there.

I love that, Will. And as you were saying that, I was just thinking, My little girl has just learned how to ride her bicycle, which is like a big milestone. The analogy I'm thinking about is you don't just put your child on a bicycle the first time ever and then just push them off and expect them to be able to ride. You know that that's going to end up with them crying on the ground, and there's a process. These days you can even start with a bicycle, with a balanced bike with no pedal, which didn't exist when I was little. That's what happened with my daughter, which was like this amazing way, but she was on that for a long time. Then she switches to the pedals and that still takes a little while to get. I feel like there's something like that as we're thinking about your gut, which is for most of us who probably grew up eating this Western diet, super processed, very little fiber, very limited amounts of vegetables, a lot of things in it that we now think of as ultra processed food and probably cause us a lot of issues, very cut off from nature, all these sorts of things, you can't expect to suddenly jump.

And it's like saying like, Oh, here's a bicycle. You're just going to ride it instantly. You know that's not going to work. And so there's something about this being a process, which I've definitely experienced myself. I guess I just feel like perhaps that's a useful metaphor.

Yeah, I love that. It is a process in a way our gut almost needs to learn for the first time or relearn to consume these foods because they largely have been stripped from the diet that we were all raised on. But much like your daughter learning to ride a bike, when you reach the point where your gut has matured in its ability to handle these foods, you get to ride off into the sunset and enjoy a bike ride. The hope would be there's no turning back.

Will, having said all of this, as a gastroenterologist, this? What's your verdict on the FODMAP diet?

I think that the verdict is, once again, we have emphasized that this is about people who have digestive symptoms. So if you don't have digestive symptoms, then I really don't see why you would ever be entertaining the low FODMAP diet. If you do have digestive symptoms, it's possible that you may find benefit and improvement of those symptoms by following a low FODMAP diet. But as we've emphasized, this is not just a restriction of FODMAPs. It's certainly not a permanent restriction. It's really important to understand that this is ultimately about building up your gut like a muscle, making it stronger, and having enhanced abilities to process and digest these foods, which can be done. That process may take time, and it also may require the expertise of people who are fragile in these concepts of the low FODMAP diet. This is why I'm a big believer and supporter, much like you did, Jonathan, and people seeking out help, such as with a dietitian.

I think if you are doing this, then obviously, firstly, you should probably be starting off talking to a doctor if you've got really bad symptoms. Secondly, I agree that I did this with a dietitian, with a nutritionist, and I think that it'd be almost impossible to do the FODMAP diet safely and well unless you're guided, because I think you could easily end up being really malnourished, where you're just basically eating rice and chicken and white bread, and you're going to get really sick. So I think this is an example where, of course, the food we eat is so important for us. So if you suddenly start to cut it all out, you can have profoundly negative impact in the same way that if you add all the good stuff, I believe obviously you can have great impact.

Completely agree.

Well, Will, I think that is much clearer for me. I never really understood what I did, and now I think I do understand what it was. I hope it's much clearer for our listeners. Thank you for navigating us so well through this rather complex story of FODMAPs.

Oh, it's my pleasure, Jonathan. And thank you for our listeners for being with us today.

If you want to understand how to support your body with the best foods for you, then you may want to try Zoe's personalized nutrition program. You can learn more and get 10% off by going to zoe. Com/podcast. I'm Jonathan Wolf.

And I'm Will Bolsoit.

Join us next week for another Zoe podcast.