Welcome to episode 60 of the Inside Knowledge podcast. I’m Anna Mapson. This week I’ve chosen to speak about the low FODMAP diet because it has coincided with me launching the ultimate low FODMAP diet guide, which will help you understand the diet, what you have to do, how to follow it, as well as how to get off it.
And that is one of the things we’re going to talk about today, is the problems with reducing your reliance on low FODMAP in order to get over your IBS symptoms. Because what happens is often people get good results from it, and then they don’t want to do this final stage of the diet, which is reintroducing the FODMAPs.
Quick intro to the low FODMAP diet
So, very, very quickly, if you don’t know what I’m talking about, the low FODMAP diet is a specific dietary intervention for people with IBS, where we take out the most fermentable fibre in the short term, get control of your symptoms. And then gradually reintroduce them one by one, so you can identify which your particular types of triggers are.
The problem is, it’s very difficult to follow on your own because it’s not as simple as just saying it’s dairy free or gluten free. It’s all about portions and how much of a certain food you can have per meal. Or actually, to be more accurate, how much of a certain FODMAP grouping you can have per meal.
It’s difficult to navigate, and that is why I created the guide that you can download on my website. And that will give you all the strategies, process steps, checklists, different meal plans. There’s one with meat and fish. One that’s vegetarian, so that it’s really easy to follow.
The link to have a look at that will be in the show notes along with a couple of other studies that I want to reference in this podcast.
What’s the research on the low FODMAP diet?
In order to talk about whether the FODMAP diet is worth all this hassle, one of the things I want to do is look at the research, look at what’s been published around the FODMAP diet, and look at the results. But it’s not as easy as just going to the summary of the research paper and saying, Oh, yes, 75 percent of people felt better on it.
That means X, Y, Z. Because what we also want to look at is
- What did the diet get compared to?
- Was there an alternative control group?
For example, who had no intervention, where we could just see sometimes being in a study, even if you don’t change anything, can sometimes affect your symptoms. And this is well known, even when we start to just measure something, it can start to change our behaviours, and change the outcomes.
So we want to look at whether these studies have included a control group.
What does the FODMAP diet get compared to?
Then also whether they had a comparison group. For example, like, a traditional type diet advice. That might be things like Cutting out coffee, cutting down on alcohol, maybe cutting out some ultra processed foods.
I’m going to go through a little bit on the NICE guidelines around IBS because those are some of comparisons to the low FODMAP diet.
Then also, sometimes they have a sham dietary advice, so like, just kind of a random selection of foods to avoid.
What are the study aims?
It’s important to understand what the study was setting out to do as well. So why did they create this study? What was the goal? And then also how did they make a comparison group or a control group? That’s first thing that I sort of always look at.
Who was being studied?
Then secondly, I always look at whether the results were for anybody who had IBS, or were they for people who had IBS C or IBS D, because this is really crucial.
Knowing whether the dietary intervention is for people who had more constipation predominant symptoms, or whether it’s people who had loose stools, is completely different. The kind of things that would work.
So no wonder sometimes it works and sometimes it doesn’t. I want to look at whether they’ve broken down their goals for the study into people who had a certain type of IBS. This is really helpful to know when we’re looking at whether the diet is effective or not.
What type of study was it?
When people are looking at research studies as well, normally a randomised, double blind placebo controlled study is what’s considered like the best kind of research study.
If a company was testing a drug, they would give some people a placebo. Which is just like a sugar pill, say, for example, and somebody else would get a painkiller. Then they would double blind them so neither the participants nor the people running the study knew which group was receiving the intervention or the placebo.
Participants in the study would be completely randomized to which group they were in. Now that makes complete sense when you’re testing a drug.
It’s hard to blind people to diet
But you can’t really do that for dietary interventions because you’re going to notice what it is you’re actually eating. Of course you’re going to know whether you’re having any dairy in your diet. Or whether you have had any bread or low fat foods or whatever.
You’re going to notice that because you’re eating it.
Are people randomized – to prevent bias
If we look at how the FODMAP diet does in some of these random control trials. Whilst we can’t blind people to their dietary intervention, you can randomize them. And you can control the trials in other ways.
Summary of low FODMAP diet effectiveness
There was a study in 2021, which looked at 13 of these randomized controlled trials of low FODMAP diet for people with IBS.
And actually, when they compared the FODMAP diet to other diets, it came out best for treating abdominal pain, abdominal bloating, and also distension. Which is like how far your stomach has bloated out. That is a good summary of how the diet has been tested and what specific symptoms it works best for.
So when they ranked the low FODMAP diet against other dietary typical interventions. Things like the NICE guidelines, which I will go through in a second, they found that when people followed a low FODMAP diet, it came out as superior for that period of time that they followed the diet.
Now, one of the drawbacks with this is they didn’t go through how easy it was for the people to follow the diet. They didn’t look at how they reintroduced the foods. And whether they came off the diet.
Managing IBS symptoms with the low FODMAP diet
But it was effective in managing the symptoms that obviously you are very keen to get under control.
If you want to go and look this up, it was a study 2021 Leeds University by Black and Colleagues. And I like this because they found like clinically significant improvements in the bloating and the pain. And so it’s really good to know that these things are effective in large groups of people because it covered 944 patients. In these 13 different studies.
Low FODMAP diet alternatives
Sometimes they do studies where they’ll compare people going on a low FODMAP diet and taking medication.
There was another study, a couple of years ago where people were randomized to be taking. This anti spasmodic type drug called Otilium bromide, which reduces the spasms in the gut, so reduces your cramps.
FODMAP vs medication
It’s an anti cholinergic, so it kind of reduces your smooth muscle in the small intestine and that can be a real big problem for people with IBS, particularly IBSD where you’re getting fast transit and really food is moving through you quickly.
In that comparison of people randomized to either follow the low FODMAP diet or to take this medication. They did see improvements with people followed the diet, but people also improved taking the medication.
The problem was in this study, they didn’t have a dietitian or any nutritionist helping them with the process. And it wasn’t really strictly low FODMAP. And so whilst you saw improvements, We don’t really know how it works because we didn’t have the full experience of doing it using, the full advice that you would get from a nutritionist.
FODMAP diet vs NICE Dietary guidelines for IBS
The other thing that the low FODMAP diet is often compared against is the NICE guidelines. So in the UK, we have the National Institute for Health and Care Excellence. and that really guides what the NHS advise people on lots of things, taking different medication and health interventions.
Their basic advice for IBS is the first line advice that should be followed before any medication is prescribed. Or before any intervention diets are prescribed. Is some of the basic things that you’ll hear me talk about a lot.
Having regular meals and eating slowly. Don’t skip meals and don’t go for long periods without eating.
Make sure you’re well hydrated, drinking about two litres of water a day. Don’t have too much coffee, too much alcohol. And then in terms of the food, try and limit some of the highest fibre foods bran. Maybe some whole grains. Then they also suggest limiting fresh fruit to three portions a day.
And a portion is about 80 grams, so still three portions a day, but not going over that, not maybe eating tons of fruit. And they suggest people with diarrhoea should avoid sorbitol, which is one of the FODMAPs, and that’s in sweeteners and chewing gum, some toothpaste, things like that. And then also, they suggest that people with gas should eat oats and linseeds, and there is some good evidence about that.
And they also suggest that psyllium husk, could also be advisable for some people. It’s worth a try, basically, they say. And they say if you try probiotics, you should take them for at least four weeks at the right dose. So there’s just a couple of summaries of the things that they suggest as a basic first line treatment instead of going down the low FODMAP route.
That study I just mentioned by Black and colleagues, they didn’t find much improvement using this advice, the NICE guidelines, in comparison to the low FODMAP diet when they had looked at these 13 different trials. They didn’t find that the NICE guidelines were that effective or that the NICE guidelines beat any of the other types of dietary interventions.
But other studies have shown that this traditional dietary advice is actually as effective as the low FODMAP diet and it’s much better tolerated by Normal people. Because unless you’re living in a research facility with all your meals provided to you, it is actually quite tricky to adjust your diet in such a way to cut out all the FODMAPs.
Another study in 2022, um, which was looking at a comparison of traditional dietary advice, gluten free and low FODMAP over four weeks and looking at how much symptom severity scores went down, there wasn’t really a clinically significant difference in these two studies. treatments and they were supported by a dietitian, told what to do and then off they went to deliver the dietary advice in their own lives.
What they found is that they all had a reduction in their symptoms. They all felt quite a lot better, but the people with the traditional dietary advice found it less time consuming to shop for, less expensive and much more easily incorporated into their own lives. The people who got the least amount of progress were the people in the traditional dietary advice, but they still did have a 42 percent improvement.
So this is still worth doing, still worth going through those small improvements, even if it’s not as improved as the low FODMAP diet or another particular diet. The reason I wanted to talk about that particular study is just that you do get some improvement from making more basic changes to your diet.
If you get significant improvements to your digestion, but you have got a very miserable life and you’re really unhappy and you’re really restricted and you can’t do anything, that also doesn’t really help your IBS either. When we’re weighing up whether the low FODMAP diet is worth it or not, it is really important to go through some of the drawbacks to going on the low FODMAP diet in the first place.
As I mentioned, it is time consuming. It takes a lot of head space to get your head around different portions, what you can and can’t eat. It is very restrictive. It’s difficult to eat out. It’s difficult to eat with friends or go on holiday whilst you’re following the restriction phase. And that can impact on your social life.
It can add to food anxiety and it can add to a. So that is something that I see quite a bit that people feel massively restricted, even if there are quite a lot of foods you can eat. And you can listen to my podcast episode number 37 about foods you can eat on the low FODMAP diet. There are ways to make it easier, but I just want to acknowledge that it feels difficult.
Also, There is this great potential that is, maybe it’s you out there, that you will stay on this low FODMAP restriction phase for way too long because the reintroduction process is too complicated. You don’t know how to get off the diet, so you stay on it for too long. Staying on the low FODMAP restriction phase does also have potential nutrition repercussions.
So a lot of people who have IBS may be deficient in iron, in B12, in calcium, and potentially zinc, and this is down to restricted intake as well as potentially problems with absorption. That is also true, but oftentimes it is mostly down to what you’re cutting out of your diet and not eating enough.
The other thing is that some people cannot go on the low FODMAP diet. For example, if you’ve had a history of eating disorders, it’s not really recommended because it is so restrictive.
Low FODMAP diet and gut microbiome
There is quite a lot of worry as well that going on the low FODMAP diet for a long time can impact your large intestine gut microbiota.
A study in the short term looked over nine different trials involving 400 different patients. They saw no effect of following the low FODMAP diet on the diversity of the microbiome. Looking at the stool samples in some of these studies, there were no differences in the total faecal short chain fatty acid production.
That is the metabolites that your good gut bacteria will make when they come into contact with fibre. That there were no differences in the concentrations of those in people who were on the low FODMAP diet and people who weren’t.
But this was a short term problem. So although the study looked over nine different trials, they were only really looking up to about 90 days.
That was the longest. And so I know that some people come to work with me and they have been following the low FODMAP diet for years. Over time, following the low FODMAP diet could lead to lower abundance of bifidobacteria. These are good, healthy bacteria that we want in our large intestine, and they help support this production of short chain fatty acids.
They also lower The pH, which makes it more acidic, which means you can absorb more nutrients like minerals and iron, for example, so they’re very good things to have. And we know that cutting out high fibre foods that on the FODMAP diet you can’t have may lead to a lower abundance of this bifidobacteria.
And, over time, that could have clinically significant consequences for your digestion and other gut microbes, like how it influences the others. Because it’s such a community of different gut microbes in your large intestine, and they kind of feed off each other. These short chain fatty acids that I was talking about, some of them produce something called acetate, and then other microbes will use that acetate to make their short chain fatty acids.
So they really rely on each other, and they feed off each other, and they need to all hang out together. If you were to follow the low FODMAP diet for a long time, The reduction in the abundance of bifidobacteria, the lower production of short chain fatty acids, may increase the chances of dysbiosis.
So it may increase the chances of bad pathogenic bacteria getting in, taking up space. Whereas if we’ve got lots of good ones in there, to crowd out the bad ones. If you’re just following the low FODMAP diet in the short term.
The restriction phase is just two to six weeks and then you’re going to start introducing higher FODMAP foods. Then you don’t need to worry about it. Because your microbes change compared to what you eat.
You can change the picture of your large intestine bacteria based on your diet. And that change can start to be seen within around two weeks.
That might not translate into symptoms, but you will see changes in the gut microbes changing from a low fibre diet to a high fibre diet, for example, in around two weeks.
And actually following the low FODMAP diet may help some people who have a very dysbiotic gut picture. Now what we don’t really have is a good sense of what is a healthy gut microbiome but what we do know is that there are particular types of families of bacteria that seem to be associated more with certain symptoms and health conditions. And that’s kind of all we can say at the moment. But there was a study in 2021, which looked at using the low FODMAP diet in order to change the gut microbiome.
So they took A group of people who had IBS. They had their stools analyzed and, people were separated into IBS pathogenic like gut microbes and IBS healthy gut microbes. So they still had IBS, but they had what the researchers considered a healthy type gut.
Some who had IBS had more of these microbes that were associated with the poor symptoms. So there were, um, these type of bacteria that they had were called Firmicutes, and they had also a lot of genes for amino acid metabolism, which can be like that sort of putrefication or like that fermentation in the large intestine, and they had low levels of helpful good good So there was like a pathogenic profile and a healthy profile.
Then they put them on the low FODMAP diet, and the healthy profile and the control group didn’t have much change to their gut microbes. But the pathogenic group, Their microbes shifted more towards the health associated gut microbiota with an increase in the good bacteria. That’s the bacterioidetes.
They had a decrease in the ones that they didn’t want. They just changed the overall, gut microbiome. I thought it was worth just talking about that because there’s always quite a lot of hoo ha about gut microbes. It’s going to be starved out by going on the low FODMAP diet, you shouldn’t follow it.
And actually, in some cases, it may help people to get control in the large intestine. So it’s not only about, reducing the good bacteria. Sometimes it can actually help you reduce the bad ones as well. And what’s interesting is this may in time be able to show us people who respond to the low FODMAP diet and people who don’t.
Maybe this is the reason why some people get a good result from following the diet and other people don’t seem to get the improvements that they’re looking for. It could be down to individual gut microbes. You know, things that are influencing whether the diet is working for you or not.
In summary
In summary, when we’re looking at is the low FODMAP diet worth it or not, I would say it is worth giving it a go, but what I suggest you do first is to follow those initial traditional dietary interventions, things like cutting out fatty spicy foods, reducing your alcohol and coffee intake, you know, eating regularly, all of those things you can find in my five non food IBS strategies.
That’s a really good place to start because it doesn’t involve changing what you eat. It just looks at how you eat and some lifestyle things that anybody can give a go. And then if you do think you’re not getting anywhere with that and you want to start looking at your diet, then I do suggest the basic traditional dietary advice first.
If you still haven’t got anywhere, then the low FODMAP diet is a really good option. But, you need to follow it carefully. If you’re going to invest your time and money and energy into following this very complicated diet, you want to make sure you’re getting the right results from it.
That is why I think my Ultimate Low FODMAP Diet Guide can be really helpful for people who are trying to go it alone. Obviously, if you want help, I do work with people one to one all over the world, and in three months, I will take you through a process to find your dietary triggers. But I know not everybody can work with me one to one, and so this product, which is out now, will help you understand the diet, understand exactly what you need to do, and make the process easy by giving you all the recipes, meals, checklists, and a full structured reintroduction process.
So you don’t need to worry and get confused, because I know it is not an easy diet to follow. Check out everything I’ve mentioned in the show notes if you want to review my products and the research papers that I mentioned as well. I’ll put a link to them down there so you can go check that out.
All right, thanks for listening to this episode of the Inside Knowledge. Better digestion for everyone.