Ep. 104: The Hidden Link Between SIBO, Iron & Ferritin

Low ferritin and digestive issues like SIBO are often treated as completely separate problems. One is considered a blood lab issue, the other a gut issue. But clinically, these two patterns frequently overlap. 

Many people struggling with SIBO, bloating, or constipation also find their ferritin stays stubbornly low despite taking iron supplements or increasing iron-rich foods. 

In this episode, we unpack how digestion, the microbiome, stomach acid, and inflammation can all influence iron absorption and regulation. When you understand that all of your symptoms are connected by shared underlying root causes the path forward becomes clearer!

In this episode, we discuss:

• Why ferritin sometimes stays low even when you are taking iron supplements
• Where iron absorption actually occurs in the digestive system
• How bacterial overgrowth in the small intestine can interfere with nutrient absorption
• The role inflammation and hepcidin play in regulating iron levels
• Why low stomach acid can contribute to both SIBO and poor iron absorption
• Emerging research around hydrogen sulfide SIBO and mineral metabolism
• The clinical patterns we often see in clients with both digestive issues and low ferritin

If you’ve ever wondered why your iron levels don’t seem to improve despite doing everything “right,” this episode will help you start connecting the dots.

SIBO won't go away? Join my training on March 29th and I will teach you exactly why your SIBO keeps coming back and what to do next 

Save your seat here

Connect + Next Steps

Want daily education, stories, and gut-friendly support?
Follow Dr. Heather on Instagram

Ready for personalized 1:1 support and a clear plan?
Apply for gutTogether®

Want a chance to win a free HTMA Bundle? Leave a rating & review and email it to happygut@drheatherfinley.co with [PODCAST REVIEW] in the subject line! We choose a new winner every month! 

Transcript

Dr. Heather Finley 0:50

Welcome to the Love Your Gut Podcast. I'm your host, Dr. Heather Finley, registered dietitian and gut health specialist. I understand the frustration of dealing with GI issues because I've been there and I spent over two decades searching for answers for my own gut issues of constipation, bloating, and stomach pain. I've dedicated my life to understanding and solving my own gut issues. And now I'm here to guide you. On this podcast, I'll help you identify the true root causes of your discomfort. So you can finally ditch your symptoms for good. My goal is to empower you with the knowledge and tools you need so that you can love your gut and it will love you right back. So if you're ready to learn a lot, gain a deeper understanding of your gut and find lasting relief. You are in the right place. Welcome to the love your gut podcast.

1:42

Have you ever noticed how certain health issues seem completely unrelated until you actually start connecting the dots? For example, I'll have two different types of clients come into our program. One will say something like, Dr. Heather, my ferritin is low. I'm exhausted all the time. The other client might say, my digestion is a mess. I'm bloated, constipated. I keep getting diagnosed with sibo. And at first glance, these sounds like two completely different problems. One sounds like a blood lab issue. The other sounds like a gut issue. But what's really interesting is that over time you start noticing something. Many of the clients who have struggled with SIBO or small intestinal bacterial overgrowth and chronic digestive issues also had iron issues or ferritin issues that refused to improve. And many of the clients trying to fix their low iron keep telling me something. I'm also bloated. I've been diagnosed with quote unquote IBS. I've had SIBO before. My stomach does feel off after meals, and that's when the pattern really starts to become clear because iron issues are often treated like a separate problem. You're told all the standard advice, take more iron, eat more red meat, vitamin C, iron infusions. And we know now that ferritin is not just about how much iron you take. It's about whether your body can actually absorb, regulate, move iron through the system. And one of the biggest factors influencing that process is your digestive system. So today I wanna talk about a connection that many people miss, but clinically shows up all the time. The connection between SIBO and low ferritin, because once you understand how these two things interact, a lot of lab patterns will make a lot more sense. Now, I want you to imagine something for a second. You keep ordering packages online, but they never arrive. So you call the company, you say, don't worry. Oh, we'll send you a new one. So your orders you order, another still doesn't arrive. They send another, still nothing. At some point you probably stop ordering packages and start asking a different question. What's happening in the delivery system? Right? And this is actually what happens with a lot of people with digestive issues or iron issues. What if the problem isn't the amount of stuff coming in? It's the delivery system responsible for absorbing it, especially when it comes to iron. That's where digestion becomes so important because one of the patterns that we see all the time is clients dealing with two issues that seem unrelated, and that's what we're gonna talk about today. So let's just start with a quick physiology refresher. Iron absorption primarily happens in the duodenum and proximal jejunum, which are the first sections of the small intestine, right after food leaves the stomach. Interestingly, this is the exact region where SIBO or small intestinal bacterial overgrowth tends to develop. SIBO stands for small intestinal bacterial overgrowth, which means that bacteria that normally live further down in the large intestine begin accumulating in the small intestine instead. So you can imagine the small intestine like a loading dock for nutrients. This is primarily where food gets absorbed. Food arrives. These nutrients are unpacked. They get loaded onto trucks, they transport them into the bloodstream, and iron is one of those nutrients that's waiting to be picked up. But if bacteria have set up shop in that loading dock, something super interesting starts to happen. Research shows that bacteria can actually compete with iron, with the host for iron. So certain microbes produce compounds. That are molecules that bind to iron very tightly. In other words, bacteria have their own strategy for grabbing iron before anything else can use it. So these studies on microbial iron metabolism show that bacteria. Can actively sequester iron from their environment and reviews on host microbe interactions. Describe this constant tug of war between microbes and the human body over iron availability. So if bacteria are overgrown in the exact. Place where iron is supposed to be absorbed. It creates a situation where iron may literally be used by microbes before the body has had the opportunity to even absorb it. And this is one reason why someone might be eating iron rich foods or even taking supplements and still feel like their ferritin barely moves. Because if the environment in the small intestine is crowded with bacteria. The body may simply not be getting first access to that iron coming in, or said another way. If bacteria are overgrown in the exact place where iron is absorbed, it's not surprising that ferritin may struggle to rise. But competition for iron isn't the only way that SIBO can interfere with ferritin because there's another layer to this that has to do with the actual structure of the health of the intestinal lining, which is a very delicate lining. Remember earlier when we talked about this small intestine being like a loading. For that system to work well, the surface of the intestine has to be in good condition, so the dock has to be functional, and that's where SIBO starts creating problems. The inside of the small intestine is designed to absorb nutrients. That's where we primarily absorb, so it has these little tiny finger-like projections called vii. Which dramatically increased the surface area for nutrient absorption. So if you could stretch out this absorptive surface in the small intestine, it would be roughly the size of a tennis court. Kind of wild, right? That's how much space the body creates to capture nutrients from food, which is amazing. But chronic bacterial overgrowth can disrupt this environment. So when bacteria accumulate in the small intestine, they produce gas metabolites, inflammatory compounds that can irritate the lining of the gut. So over time, this can lead to several structural changes that researchers have observed in sibo, and one of those is the inflammation of the intestinal lining, what some people online will call leaky gut. Or intestinal permeability. Another is something called villus. Blunting, which means that these finger-like projections that normally help us to absorb nutrients, begin to flatten or soften or shorten. And when that happens, the surface area available for nutrient absorption becomes smaller and smaller and smaller. So SIBO can create intestinal permeability. Or leaky gut, whatever you wanna call it, where the barrier function of the intestinal lining becomes compromised. And so basically, when these changes occur, the gut simply becomes less efficient at absorbing nutrients. And of course, iron is one of these, but not the only one. Clients with chronic digestive issues related to SIBO often struggle with absorbing nutrients like B12 fat soluble vitamins like Vitamin A, DEK. And sometimes other amino acids and minerals. So when someone is dealing with bacterial overgrowth in the intestine, the issue isn't bacteria competing for nutrients. It's also that the environment responsible for absorbing those nutrients may not be functioning optimally. And so if the section of the intestine responsible for absorbing iron becomes damaged or inflamed, it becomes much harder for ferritin to rise, even if iron intake looks good on paper. So this mechanism is really well described in SIBO literature, and it's one of the reasons that digestive health plays such an important role in nutrient status. There's another layer to this that makes the iron connection and conversation even more interesting. Because even if iron is present in the gut, someone is eating iron-rich foods taking supplements, the body still has another checkpoint that determines whether iron is actually allowed circulation. And that checkpoint is controlled by a hormone called hepcidin. So hepcidin acts like the traffic controller for iron in the body, and it's gonna regulate how much iron is absorbed from the intestine and how much iron gets released into circulation. So when hepcidin levels are low, iron absorption is allowed to happen normally. But when hepcidin levels rise, the body essentially puts the brakes on iron movement. It's like we have an emergency stop, so iron absorption from the intestine decreases and instead gets trapped inside of these storage cells, so the amount of iron circulating in the bloodstream is gonna drop. One of the biggest triggers for increased hepcidin is inflammation. Now there's so many reasons that could cause inflammation. This is actually not a bad thing, it's just part of the body's protective response. Many microbes rely on iron to survive, so when the immune system detects inflammation or infection, the body is gonna intentionally limit iron availability as a defense mechanism. You could think of it like locking away the fuel supply so bacteria can't access it. So the challenge is that when inflammation is ongoing, this protective mechanism is going to affect the host, and that's where SIBO plays a big role because bacterial overgrowth in the small intestine often creates. This low grade chronic inflammation in the gut. And when that inflammation signal is present, the body may increase hepcidin production. So hepcidin goes up, iron absorption in the intestine goes down. So even if someone is taking supplements, the body is not gonna allow that iron to move into circulation. And instead, iron can become trapped in storage. So this pattern is sometimes referred to as. Anemia of chronic inflammation or functional iron deficiency. So basically, in other words, iron may technically be present in the body, but the body is not moving it where it needs to go. And this is why someone can feel exhausted, have symptoms of low iron, still struggle to increase their ferritin de despite supplementation, because the issue isn't always the amount coming in. It's the signals controlling how iron moves through the body. So we talked about a few ways that SIBO can interfere with iron bacteria competing for it changes in the intestinal lining, inflammation increasing hepcidin. But there's another piece of the puzzle that shows up even earlier in the process, and I always stress this on trainings that I run. In fact, the practitioner training that I'm going to run this is a heavy emphasis because in many cases, the same factor that contributes to sibo. Can also interfere with iron absorption from the very start. And one of the major risk factors for SIBO is low stomach acid, also known as hypochlorhydria. Stomach acid is gonna play several important roles in digestion. It helps break down proteins. It releases enzymes, it triggers bile flow, and it acts as one of the body's first lines of defense against bacteria. So when stomach acid levels are strong, many microbes enter through food are neutralized before they ever reach the small intestine because they're killed off. But when stomach acid is low, bacteria can survive. So over time, this can allow microbes to migrate further into the digestive tract and begin to accumulate in the small intestine, which increases the risk of sibo. So where does this, or why is this relevant for iron? Because iron and food doesn't start out in the exact form that the body can absorb, it often needs to be converted into an absorbable form. And stomach acid helps to facilitate that process. So when stomach acid is low, iron absorption becomes less efficient right from the start. This creates a really interesting chain reaction. It looks like low stomach acid, poor iron absorption. That same low stomach acid environment increases the risk of SIBO to develop. And once SIBO is present, we have additional layers of interference with nutrient absorption. So the pattern can then look like low stomach acid, poor iron absorption. Higher risk for bacterial overgrowth in the small intestine. Further disruption of digestion and nutrient absorption. This is one of the reasons that digestion plays such an important role when someone is trying to improve ferritin levels, because if the environment responsible for breaking down and absorbing nutrients isn't functioning well, simply just adding more iron is not gonna solve the underlying issue. The real work is restoring how digestion functions in the first place. So now at this point you might be thinking, okay, this makes sense. Bacteria compete for iron changes in the intestinal lining, inflammation affects iron regulation, low stomach acid contributes to poor iron absorption. The natural question that you might be thinking is, do we actually see this connection in real life? And the answer is, yes. While the research isn't always designed to look specifically at ferritin, several studies and observations have documented iron deficiency in populations dealing with bacterial overgrowth, either in the small or large intestine. And so some smaller studies and clinical observations have shown an association between SIBO and iron deficiency anemia. In certain cases, patients with unexplained iron deficiency were later found to have bacterial overgrowth in the small intestine. And when that bacterial overgrowth was addressed, iron markers began to improve. And I can say clinically we have seen this a lot as well. Research has observed these patterns. For example, some patients who appear to have celiac like symptoms, including nutrient deficiencies like B12 digestive issues. Are ultimately found to have SIBO instead of true celiac disease. I'm presenting a case in my practitioner training on this, where a lot of her markers, even on the GI map, pointed towards Celiac high calprotectin, high anti glidden, high secretory, IGA. She actually didn't have celiac. Her intestines just had a lot of inflammation, and once we got that calmed down, she wasn't reactive anymore. So similar patterns have been noted in IBS populations where micronutrient deficiencies iron deficiency. They appear frequently in individuals with chronic digestive dysfunction and in broader malabsorption syndromes as well. Iron deficiencies one of the first nutrient deficiencies to appear because iron absorption is so dependent on the health of the small intestine. So just to be clear, these studies don't always isolate ferritin, and they don't suggest that SIBO is the only cause of iron deficiency. We know that's not the case, but what they do show is that when the small intestine is struggling, iron status is affected. Which brings us back to this theme that I've been talking about through this whole episode, is that ferritin is not just about how much iron you consume, and I feel like I've stressed that over and over and over again in so many of the trainings that I've run recently. So to be clear, SIBO iss not the only reason ferritin can stay low. There's other factors, heavy menstrual cycles, chronic stress, mineral imbalances, poor bile flow, low protein intake. Iron metabolism is gonna be influenced by so many systems. Digestion is one of those pieces that often gets overlooked, and we know that when digestion improves, many other systems start working better. There's one more angle here that's starting to gain attention, and it has to do with a specific type of sibo. So there's three types. Hydrogen methane, hydrogen sulfide. Now the area of research around hydrogen sulfide is still emerging. But it is really interesting because of the connection between gut bacteria and iron. So hydrogen sulfide producing bacteria will behave a little differently than some of the other microbes involved in the other types of sibo. These bacteria interact heavily with sulfur metabolism. And the compounds they produce can influence several systems in the body. Hydrogen sulfide itself can affect mitochondrial function, which is one of the reasons that people with this type of overgrowth have significant fatigue a lot of the times. It can also influence redox balance, inflammatory signaling, which ties back to inflammation. But another interesting connection is that some sulfur reducing bacteria also interact with iron. Iron is going to play. A role in several microbial enzymatic pathways, meaning bacteria may use iron as part of their process. So in certain environments, iron becomes part of that activity happening between the microbiome and the host. So this is still evolving. We don't need to go too far down the rabbit hole here, but it does reinforce just this idea that the microbiome, mineral metabolism, they're deeply connected. And when the microbiome shifts, nutrient dynamics in the body can shift as well. So one of the most compelling pieces of this conversation isn't just the physiology or the research, it's the patterns that us clinicians see every day. Because when we look at clients who struggle with ferritin that won't improve, or SIBO that won't improve the story is so familiar. They have chronic bloating, constipation. A ferritin is stuck. Iron supplements don't move the needle. Sibo, antibiotics don't work. All this stuff. And when you piece these things together, we can see these patterns that emerge. And one of the things we see over and over again is just this connection here. So we wanna zoom out, we wanna look at how the whole system is functioning because none of this happens in isolation. So. If this episode resonated with you, you are someone who has struggled with sibo, bloating, constipation, iron levels that just don't seem to budge despite doing all the right things. If you've been struggling with low ferritin or SIBO and you're wondering how these things are connected, or maybe you have SIBO and you're suspecting you have low ferritin or iron issues because you're so tired, or you have B12 deficiencies, you think you might have celiac disease. The question that we wanna ask is, how well is my digestive system functioning? Um, not just how do I get rid of the SIBO or should I take more iron because none of this works in isolation. This relies on an entire system working together. When digestion motility microbiome health begins to improve, the body often becomes much better at absorbing and utilizing the nutrients that we need, which is so cool and so fixable, which is amazing. This is exactly why understanding the bigger digestive picture matters and. That helps because then you aren't chasing individual symptoms. You're seeing how the system works together. If you wanna learn more about how we're doing this, I'm running a webinar on March 22nd. It's called SIBO Unlocked. In this training, I'm gonna walk you through why antibiotic supplements, elimination diets don't create lasting relief, how to identify the actual patterns driving your sibo, how digestion, motility, minerals, nervous system, how all that fits into gut healing. You can find the registration in the show notes. So thanks so much for joining. I hope this was helpful. Would love your feedback, and I'll see you next time.