EP.359/ Is The Low FODMAP Diet Helpful for Those With Both Endo and SIBO?

Podcast

23 Aug

Recently we’ve been talking about the low FODMAP diet and how it can be helpful for histamine issues and endometriosis symptoms… but what about what it was designed for - IBS, and by default, SIBO?

Before we get into this topic, let’s do a recap of what the low FODMAP diet is.

Now, why does improving IBS and/or SIBO matter for endometriosis? Because multiple studies have now linked SIBO with endometriosis, with the latest research finding 91% of endo patients also had SIBO and/or Intestinal Methanogen Overgrowth/IMO - which is what we used to call methane SIBO.

To add that, a recent meta-analysis found that in almost 19,000 endometriosis patients, the risk of IBS was three times higher than those without endo, with a 2024 study finding that 47.8% of endo patients had a previous diagnosis of IBS.

But why does this matter? Well, research is showing that the microbiome of the gut is in fact influencing the development and progression of endometriosis. So, by understanding and improving the gut, the hope is we can improve endo symptoms and maybe one day, even find a cure.

So, the low FODMAP diet was designed originally and is still used primarily for IBS. Its effectiveness for IBS varies in the studies, but it can be as high as 75% or even 85%, but in others, closer to 50%.

So, why the discrepancy?

There are likely multiple reasons, but one of them is very likely to be the presence of SIBO.

The latest research estimates that somewhere in the region of 60% of IBS patients actually have SIBO, and this is based on the latest data by Dr Mark Pimentel, though some studies estimate these figures as being lower such as 38% (having said that, they are very small).

This can affect the efficacy of the low FODMAP diet because the low FODMAP diet doesn’t lower all types of carbohydrates. This matters because the bacteria and archaea that cause SIBO, IMO and ISO (new name for hydrogen sulphide SIBO), love to eat carbohydrates - that’s the food they live off and thrive off. Now, all carbohydrates are fermentable, meaning they all have the ability to be fermented (a.k.a eaten) by our gut bugs, whether that’s gut bugs in our large intestine where they should be, or those living in our small intestine, in the case of SIBO. So any type of carbohydrate has the possibility of triggering symptoms. Now, pay attention to the word ‘possibility’ here, because not all carbs will cause you symptoms. It comes down to individual tolerance, based on the type of bacteria you have, where you SIBO is located in the small intestine, how much you have of that bacteria, serving sizes of the carbs and so on. When it comes to SIBO food triggers, it’s very individual.

The low FOMDAP diet only reduces some fermentable carbohydrates; oligosaccharides, disaccharides, monosaccharides, and polyols, but it leaves in polysaccharides like starches and resistant starch, and some monosaccharides like glucose.

As a result, Dr Siebecker, along with five other SIBO experts who combined, have seen thousands of SIBO patients, report the low FODMAP diet as ‘hit or miss’ for SIBO symptom management, because for some SIBO patients, they can’t tolerate starches, or simple sugars like glucose. This is why there are other types of SIBO diets, like Dr Siebecker’s SIBO Specific Food Guide and Dr Mark Pimentel’s Low Fermentation Eating Diet, for example. They are broader and they restrict more carbohydrate sources.

But this is where tailoring is needed. You and I are not just SIBO and IBS patients, we’re endo patients too - and many of us listening, have full blown histamine intolerance or mast cell activation syndrome, or at the very least, have mast cell and histamine involvement in our endometriosis symptoms and progression, as we know that they are involved in endo development.

And we know that the low FODMAP diet has shown great promise for reducing histamine levels and improving not just IBS symptoms in endo patients, but even endo symptoms like daily pelvic pain and improves our quality of life.

The other thing worth considering is your personal emotional response to these diets. The low FODMAP diet, in the SIBO world at least, is sort of in the middle when it comes to restriction - with diets like the SIBO Bi-Phasic being at the upper end of restriction. As someone who has tried them all, my personal take is that the low FODMAP diet is easier than some of the more SIBO specific diets. It tends to allow for a broader range of foods, it’s just that some are in smaller or more moderate quantities.

Does that mean you’ll find it easy? No, for many, the low FODMAP diet is very challenging and can be triggering for some, so just because I find it to be easier than the Bi-Phasic or SIBO Specific Food Guide, does not mean you will, or that you’re weak or a failure if you find it hard or triggering.

One of the things I like about the low FODMAP diet is that it’s time specific and structured, you know there’s an end to it - you do 2-6 weeks of restriction, and then several weeks of reintroduction and identifying your specific triggers that you’ll need to minimise and manage moving forward. It allows you to develop a tailored nutritional protocol for you, that includes the FODMAPS you personally tolerate, and moderates the ones you don’t - so you end up with an expanded diet of the foods you do well on, and a guide for how to limit the ones you don’t. And whilst there are diets that have a similar-ish approach like the Bi-Phasic diet, as I said, they tend to be more restrictive and we don’t yet have any evidence on their effectiveness for endo (that doesn’t mean they won’t help, it just means we haven’t studied them in endo patients yet).

Now, to be clear - every SIBO diet is supposed to be short term, and is supposed to be tailored and expanded to tolerance, so none of these are supposed to keep you in a restricted phase for a long period of time. And another thing to be very clear on is that none of these diets clear SIBO, they are not treatments for SIBO alone, they are supportive to the actual treatments and can help manage symptoms and also keep us in remission after successful eradication. If you’d like to learn more about that and what treatments do actually work, I’ve linked to a few of my SIBO resources in the show notes.

Finally, another really important point to emphasise is that most doctors, including Dr Siebecker, recommend starting with the least restrictive SIBO diet, and only moving towards the more restrictive diets if you don’t see improvements. The low FODMAP diet is a sort of middle of the road diet for SIBO, with the Paleo diet being a fairly low carb diet to consider trying beforehand. Of course, again, we don’t really have much in the way of data for the paleo diet and SIBO, IBS or endo - but again, that doesn’t mean it won’t help you.

Now, if you’re listening to this and are thinking “Omg, now I have to do the low FODMAP diet to manage endo” - no, you don’t. You’ll know, if you’ve listened long enough, that we see incredible improvements in endo symptoms like pain, with a general healthy anti-inflammatory diet that reduces things like added sugar and processed foods. But, if you’re someone who has IBS symptoms and/or endo belly, or even a diagnosis of IBS, or you have SIBO, and maybe you have histamine issues to boot, you might find that a low FODMAP diet helps calm your symptoms and helps you to devise a nutritional plan moving forward that is tailored to some of your most specific triggers.

Lastly, I want to remind that the low FODMAP diet is a medical diet that should be prescribed and overseen by a doctor and/or dietician. So, if you’re interested in trying it, take these studies to your doctor and have a conversation with them about the benefits for IBS and endo, and whether trying the diet could help you. Of course, we all know that doctors can be very dismissive, so you may need to share specific studies with them, or seek a more open-minded doctor or dietician.

Show notes

Low FODMAP diet info

https://www.monashfodmap.com/about-fodmap-and-ibs/

https://pmc.ncbi.nlm.nih.gov/articles/PMC4918736/

IBS and SIBO

https://www.youtube.com/watch?v=Sv8LjTgpmP0

https://www.ibssmart.com/sibo-symptoms-and-diagnosis

https://www.nature.com/articles/s41598-022-05933-1

https://www.msjonline.org/index.php/ijrms/article/view/15048

SIBO and endometriosis

https://pubmed.ncbi.nlm.nih.gov/39959963/

https://pubmed.ncbi.nlm.nih.gov/9660426/