Hello, welcome to episode 71 of the Inside Knowledge podcast for people with IBS. I’m Anna Mapson. This week I’m doing something a little bit different by pulling out these three unrelated papers and just pulling out some highlights.
Three new science papers on IBS & SIBO
The first one is all about the oral microbiome. That’s your teeth, your gums, your bacteria, and also your gut health. What is the connection? And we’re going to go through that. Secondly, there’s one about the difference between SIBO and IBS. I thought this was really interesting because there really aren’t many studies which specifically look at the difference in symptoms for people who’ve got IBS or SIBO. Quite often they are in the same pot of research. So this is a really interesting paper.
And then thirdly, we’re going to look at some specific subtypes of SIBO. So that’s the hydrogen positive or methane positive or hydrogen and methane. They looked at the differences in nutrients in the blood but also in their diet. And this is really interesting and I think will be helpful for lots of you if you have SIBO.
Oral health and digestion
Right, so the first one I’m looking at is called Oral Health and Modern Digestive Diseases, Pathophysiologic and Aetiologic Factors. What a mouthful. This paper is a review rather than something where they’ve got people in and tested on them and then they’re showing the results.
They’re looking at the literature and looking for links in the literature between problems with people losing teeth, having dental caries, and also dysbiosis. So that includes things like IBS, but also small intestine bacterial overgrowth, SIBO. It’s really interesting, and I felt like I wanted to explain it a bit. I probably need to do a whole episode on oral health and your digestion.
That’s a future episode, but also what, what is really interesting is that a lot of the studies, they do show links between the health of your mouth and the state of your digestion.
People who have IBS are much more likely to have periodontitis.
Periodontitis is inflammation to your gums. So perhaps you see bleeding gums when you brush your teeth. And your gums may even be receding as well. This can just be because you have got a layer of bacteria living on the gum. And that is interfering with the way it should be sucked up to the teeth.
It should be kind of really tightly in there. But when there is a low level of infection, it can just cause the gum to come away from the teeth a little bit and then it creates these pockets where more bacteria is kept. And actually some of these specific bacteria have been found, in SIBO and can also be found in your mouth.
SIBO microbes in the mouth
There are particular bacteria called streptococcus mutans, which is also involved in dental caries. So that’s cavities and holes in your mouth. And also another type of bacterial species called Prevotella. They are more common in the mouths of people who’ve got SIBO. And also we see that Klebsiella, another type of bacteria that is also implicated in people who have SIBO can also be found in the saliva of people who have IBS.
Now, the interesting thing about Klebsiella as well is that it can increase the amount of histamine that you have in your gut. Some people find that they have higher histamine reactions and tend to have higher abdominal pain levels. But also the other histamine symptoms that you might be getting is like runny nose, itchy eyes, itchy skin, those typical sort of hay fever or allergy type symptoms.
Histamine in the gut
Those are often down to high histamine which may be triggered in some part by this bacteria that actually degrades histidine into histamine. So it can increase the levels of histamine in your digestive system.
There is a three way interconnection between your mouth, your gut and the liver as well. And so the liver gets a blood flow from the gut. So if you’ve got bacteria that you’re swallowing in your mouth and some bacteria like one that’s called, Porphyromanos gingivalis in your bloodstream, it can actually survive the stomach acid. So often stomach acid is one of the first lines of defence for stopping bacteria that’s coming through the mouth. In our food and stopping it reach the intestines.
Stomach acid as a defence against SIBO
But if you’ve got low levels of stomach acid, perhaps you’re taking a PPI, perhaps you’re chronically stressed and your stomach acid is particularly low, then this may increase the amount of bacteria that is going into the small intestine. And it may also just survive, even if you’ve got high levels of stomach acid.
So, some of the bacteria can get into your small intestine and if there is a case of Dysbiosis in the small or large intestine, that means that the mucus lining of your digestive tract is not as strong as it was. And bacteria from the mouth can actually start to colonize it or start to get involved and change the ecology of bacteria in the gut.
Liver health and your oral microbiome
In animal studies, both of those bacteria, the Streptococcus mutans and the Porphyromannus gingivalis have been shown to affect liver health as well and also to change the gut microbiome, so basically to kill off some species and encourage others. Basically, when they’ve added that bacteria to the guts of mice in experiments, it has had a negative effect on their digestion.
The reason I wanted to include this study is just because the one thing that you can take from this is it is important to go to your dentist. Get your hygienist appointments where they scrape and clean your teeth. Really to brush your teeth properly for two minutes every day and actually do it properly.
Just really keep up the oral microbiome health because there’s a knock on impact. Not just on your digestion, but on other organs and inflammatory processes in the body. So really important. And that is one of the reasons I picked it.
Differences in IBS & SIBO
Right, let’s move on. The second study is called Differences in Clinical Manifestations and the Fecal Microbiome between Irritable Bowel Syndrome and Small Intestinal Bacterial Overgrowth.
This was a relatively small study, but it had groups of Chinese patients, who had IBS, some had SIBO.
They had a group of healthy controls, and there was between 70 and 80 people in each group. The people in the IBS group did not have SIBO and they were ruled negative for SIBO by a lactulose breath test. And then the people who had SIBO had a positive test and then the healthy controls didn’t have IBS symptoms or they didn’t have SIBO.
The thing about this test that I liked is that they separated out the difference between IBS and SIBO and often that’s not ruled out. So people are just in a research study, but we don’t know whether they’ve got SIBO as well because it hasn’t been tested. So this was helpful.
Differences in symptoms between IBS & SIBO
In terms of symptoms, people who had IBS generally had higher abdominal pain, more frequent diarrhoea, and actually worse symptoms when they were self rating their symptoms than people who had SIBO.
Differences in diet between IBS & SIBO
In terms of their diet, they found people who had IBS ate more protein and ate less fibre. And in contrast, the people who had SIBO ate a higher fat diet and they were low carb, generally. So not necessarily just fibre, but just low carb.
Gut microbe changes between IBS & SIBO
And then they also did a gut microbiome test as well, looking at the faecal microbial signatures of people who had IBS and SIBO. This is looking at the microbes in the large intestine, and actually we can only get a sample of what’s in the large intestine because this is what’s coming out in the waste. But there’s a really important picture showing that a lot of bacteria is not released in the waste and actually lives in the mucous lining of the large intestine and may never come out in the poo. And so sometimes you have bacteria that do not show up in a stool test.
However, what they did show, that there was a difference between people who had IBS and SIBO. Obviously the people who had SIBO, you might think it’s kind of natural, they had much more gas producing bacteria.
SIBO bacteria
People who had SIBO also were more likely to have another bacterial group called Christensenellaeaceae, which is associated with a longer intestinal transit time. So, of course, if you think about SIBO . You’re getting that overgrowth because of a slow transit time through the small and large intestine and that is allowing the bacteria to grow.
So, of course, it makes sense that you have more of these bacteria. But also they had bacteria which may be affecting carbohydrate breakdown. And so it makes sense that people who had SIBO were going on a low carb diet in order to manage their symptoms.
IBS gut bacteria
In the people who had IBS, they had a lower gut diversity, so less variety in the types of microbes that were available in their stool samples.
And they had higher incidence of bacteria like E. coli, Enterobacti, and then another group called Doreae. And all of those types of bacteria are associated with inflammation to the gut lining. These are potentially the causes of that abdominal pain, the bloating, and these are also, some of them are linked to previous infections.
Post infectious IBS
we know that post infectious IBS is a really common cause of IBS and potentially these pathogenic bacteria such as E. coli or Shigella. These are more likely to be raised in people who have IBS. Showing that potentially that is one of the causes of IBS, caused by an acute infection Like food poisoning or something.
If you want to know more about the mechanics of how that works, listen to episode 10 when I talked about post infectious IBS as a common cause of your irritable bowel syndrome.
Testing for SIBO is important
And the reason I wanted to bring this study to your attention is just to highlight the importance of testing for SIBO. If you feel that you may have SIBO, it’s really important to understand if that is the trigger for your, if that is the driver of your symptoms. So, Do speak to your doctor about getting tested to rule out SIBO as a cause because if you have got SIBO, it’s something you can treat.
It’s tricky and it’s difficult, but I would definitely go ahead and try to look at SIBO as one of the causes of your symptoms.
SIBO subtypes and nutritional status
The third study I want to cover today is called Identification of SIBO subtypes along with nutritional status and diet as key elements of SIBO therapy. The aim of this study was to look at correlations between SIBO subtypes, so that’s hydrogen, methane, or hydrogen and methane.
And whether it impacts on your nutritional status and your dietary intake. It was a very small study, so unfortunately that is one of the key drawbacks. It only included 67 people who were newly diagnosed with SIBO. And this is also a drawback because these people haven’t had SIBO for years. And so this may have affected some of their dietary choices which we’ll come back to at the end.
So those are the kind of drawbacks.
But what I liked about it is it’s in people, it’s real human study, and it is specifically looking at nutrients and diet, because if you’ve got SIBO and you belong to any SIBO groups online, you will see a lot of, concern and panic in some cases about nutritional deficiencies and how these are influenced by the presence of bacteria in the small intestine.
So in this study, 51 percent had hydrogen and methane, 31 percent had just methane, and 18 percent had hydrogen only. So these are quite small numbers. Bearing in mind 67 people, you’re only really looking at a group of 30 who had those main symptoms, and that’s how they’ve done their nutritional analysis, so we’re looking at quite a small closed group.
Low nutrients in SIBO
The key headlines were, people who had hydrogen and methane, had low serum vitamin D, low serum ferritin, that’s your iron stores. And a low fibre intake. And these were clinically significant results. These were not caused by something else that could have confounded the results. So if we get a bit more into the detail of each of the nutrients.
Vitamin D and SIBO
In vitamin D, what was interesting is they called optimal between 30 and 50 nanograms per millilitre. But actually some might argue that optimal is actually over 50, and that is not particularly high. In the UK, we don’t necessarily consider over 50 to be high. We actually say, in the NHS that between 50 and 75 is adequate, and optimum is actually over 75.
So when you use those markers, in this study, everybody was less than optimum in terms of their vitamin D status. They also found is that the people who had higher levels of hydrogen also had lower levels of their serum vitamin D. So there was a correlation between the more SIBO that you had, the worse your vitamin D was.
B12 and hydrogen positive SIBO
Looking at the vitamin B12 assessments around 50 percent of people who are hydrogen positive SIBO showed borderline levels of vitamin B12. So that’s borderline deficiency. And yet again, they’ve used quite low levels as the cut off for what is optimal and what is deficient.
The interesting things I want to bring in is firstly, these were newly diagnosed people with SIBO who may not have had it for too long. When they looked at the dietary intake, 58 percent of people who had that hydrogen positive SIBO did not meet their vitamin B12 requirements.
Undereating B12 rich foods can lead to deficiency
They weren’t eating enough of the vitamin B rich foods in order to get their levels up. So yes, they were taking quite a low cut off point for deficient, and if we’d used optimal levels, might have been even higher. However If you look at whether they’re eating enough, you can’t expect to have high levels of vitamin B12 if you’re not actually eating very much.
It might be possible that the B12 is not getting absorbed because bacteria in the small intestine are competing with you for the nutrients. The microbes are taking your B12. Or bacteria could be damaging one of the sites that cobalamin, (that’s like the part of B12 that we absorb). That could be damaged on the cells by, the bacteria just being there or upsetting the mucous lining of your small intestine.
Methane dominant SIBO and B12
In other studies, they’ve also shown that people who have methane predominant symptoms do not necessarily have a B12 deficiency. That is potentially because certain types of methane producing microbes, like Methanobrevibacter smithii, for example, have actually got the ability to synthesize cobalamin for itself.
So they can almost make their own B12 because they do need it to survive. But they don’t need to steal your B12. That’s where there could be a bit of a difference between people who have hydrogen and people who have methane predominance. That’s not in this study, but in other studies, they’ve shown that B12 is not necessarily low for people who are methane predominant.
Iron levels in methane dominant SIBO
When they looked at iron, the methane positive group had low ferritin levels, that’s your iron stores, which is indicative of early iron deficiency anaemia. Dietary intake was actually okay. They were eating enough, but their actual iron stores were quite low.
Iron is actually really important for your large intestine bacteria. Some of it’s absorbed in your small intestine and gets used up in the body. Some of the iron travels to the large intestine where it is used by your gut bacteria. When you’ve got low iron certain gut bacteria can thrive. And actually these includes Klebsiella, Salmonella and E. coli.
Remember going back to the previous study where we looked at those were likely to be higher bacteria in people who had IBS. Those thrive when you’ve got a low iron environment, but also certain bacteria can change the acid profile of the gut and we want it to be a little bit more acidic so that you can absorb the more iron.
Methanogens can use your iron
And one of the possible reasons for Iron being low in people who have high methane is that the methane microbes, or they’re called archaea, they actually use iron to grow.
So that’s where we have that correlation. Remember back those people who had methane positive SIBO were actually more likely to be deficient in their iron stores in their body. So their bacteria is using the iron instead of them.
Undereating iron rich foods can cause anaemia
Part of the reason I wanted to bring out this study, is that what was really also important, I feel, is that over 50 percent of the people in this study were not meeting their total energy intake requirements. They were not eating enough calories and enough food. Nearly all of them were not eating enough fibre.
Dietary fibre in SIBO
The people who had methane dominant SIBO were eating a bit more fibre. But the majority of people were not eating enough fibre. Now when you don’t have good levels of fibre in your gut, you will struggle to form a good gut a solid bowel movement.
So you might have more diarrhoea or more constipation. And these are the key elements of either the hydrogen or the methane positive type of SIBO.
Low fibre diet can be a root cause of SIBO
The authors of the study also say that decreasing your fibre intake could be increasing the risk of SIBO development by slowing down your gut motility and disrupting the bacterial balance.
So they are really clearly pulling out and I would really stress to you as well that cutting fibre out of your diet could be making symptoms worse and lasting for longer.
Check your nutrient levels
That is part of my reason for bringing this study to you really, is to first of all suggest that you go and get a blood test and actually test whether your levels are okay for vitamin D, B12, iron and your folate levels.
It’s helpful that information to know whether you are eating enough of these foods in the first place in order to get sufficient levels. And if you are eating enough, but you’re not absorbing them? Maybe it could be down to the bacteria in your small or large intestine affecting your absorption rates.
So that would be the first bit of advice if you’re worried about your nutritional status, is to go and get it tested. You can do this privately or your doctor should do a full blood panel if you go and ask them.
Eat fibre to protect your gut
Then, also the fibre was too low in the majority of people in this study, and it is something I see in my clients all the time.
People who don’t eat enough fibre because you’re trying to manage symptoms, but actually it could be exacerbating things and making things worse. And then the third bit of information was that their energy intake was generally too low. So they weren’t eating enough calories. to keep them going. And probably not enough diversity as well, is what I would assume.
However, that wasn’t a metric in this study.
Conclusion to today’s episode
I hope you found those three little study overviews interesting. I’m always reading science papers about SIBO and IBS and general gut health stuff to see if there’s anything new and interesting that I can translate into practical applications for my clients.
I thought those three things together give you something practical that you can think about whether it affects you or not. If you’ve been enjoying my podcast, please, please would you leave me a review.
On Apple Podcasts you can rate and review. On Spotify I think you can just leave a rating. It would really help me if you would just give me a quick review or click the rating button to let me know how you’re getting on. The more ratings I get, the more people will hopefully hear about the podcast.
But thanks for listening to this episode of the Inside Knowledge podcast.
Better digestion for everyone.