Is leaky gut the same as IBS?

No, they are not the same condition. “Leaky gut” is a term commonly used to describe increased intestinal permeability, meaning the intestinal barrier may not regulate what passes through it as tightly as normal. IBS (Irritable Bowel Syndrome) is a clinical diagnosis defined by recurrent abdominal pain associated with changes in bowel habits, such as diarrhea, constipation, or both. While some individuals with IBS may show measurable changes in gut barrier function, some do not, and increased permeability can also occur in people without IBS. They can overlap in certain cases, but they represent different physiological processes and are not interchangeable.

Can SIBO cause leaky gut?

Research suggests that SIBO (Small Intestinal Bacterial Overgrowth) does not automatically cause leaky gut, but it can contribute to it in some people. In SIBO, too many bacteria grow in the small intestine and begin fermenting carbohydrates too early in digestion. This can lead to gas, bloating, and gut irritation. Over time, repeated stress from bacterial overgrowth and immune activation may affect how tightly the intestinal lining regulates what passes through it, potentially increasing intestinal permeability (the more scientific term for leaky gut). However, not everyone with SIBO develops leaky gut, and increased intestinal permeability can occur for other reasons as well. The connection is possible and supported by biological mechanisms, but it is not guaranteed in every case.

Can leaky gut cause IBS?

Increased intestinal permeability (often called “leaky gut”) may play a role in IBS for some people, but it is unlikely to be the sole cause. IBS is considered a multifactorial condition involving changes in gut motility, nerve sensitivity, immune signaling, and the gut microbiome. When the intestinal barrier becomes more permeable, it may contribute to immune activation and heightened gut sensitivity, which can worsen symptoms such as pain, bloating, diarrhea, or constipation. However, not everyone with IBS has increased intestinal permeability, and not everyone with leaky gut develops IBS. Because symptoms overlap and multiple mechanisms may be involved, testing for underlying drivers (such as microbial overgrowth or post-infectious markers) can help clarify what is contributing to your symptoms and guide you and your providers to a more targeted treatment approach.

Celiac and Bloating: Why Gut Symptoms May Continue After Going Gluten-Free

If you have celiac disease, going gluten-free is probably the hardest dietary change you've ever made. You've learned to read labels, found new ways to cook, navigated restaurant menus with more questions than anyone at the table, and said no to foods you used to love. You did all of it because you believed, and were told, that removing gluten would help you feel better.

For many people with celiac disease, it does. But for others, the bloating, gas, diarrhea, or constipation just doesn't fully go away. Even after months of strict adherence, something still feels off.

If that's been your experience, you're not imagining it. And just as importantly, you're not alone. A significant number of people with celiac disease continue to experience gut symptoms despite doing everything right with their new diet. Several things can explain persistent symptoms, but one of the most commonly overlooked is a condition called Small Intestinal Bacterial Overgrowth, or SIBO.

SIBO, along with two closely related conditions called Intestinal Methanogen Overgrowth (IMO) and Intestinal Sulfide Overproduction (ISO), can produce symptoms that are very similar to celiac disease itself. And research shows that celiac patients face a meaningfully higher risk of developing these overgrowths than the general population.[1]

Understanding the connection between celiac disease and microbial overgrowth could be the missing piece in your pursuit of answers and relief. Let’s take a closer look at how these conditions relate, and what could be going on inside your gut.

What Celiac Disease Does to Your Gut (Beyond the Gluten Problem)

Most people with celiac disease know the basic story: gluten triggers an immune response that damages the lining of the small intestine, leading to inflammation, impaired nutrient absorption, and a range of symptoms that can include diarrhea, bloating, abdominal pain, fatigue, and more. Nearly 1% of Americans have celiac disease, though many more are estimated to be undiagnosed.[2]

What's less commonly discussed is what celiac disease does to your gut beyond the immediate gluten response. The chronic inflammation that comes with celiac disease damages your villi: the tiny, finger-like projections that line the small intestine and are responsible for absorbing nutrients from food into the bloodstream. And that same inflammation also disrupts the broader biological environment of the gut (your microbiome) in ways that can linger long after gluten is removed from the picture.

One of the most significant of these disruptions targets gut motility. When your digestive system is working properly it produces coordinated, rhythmic contractions that move food through your digestive tract at regular intervals. Research has established that patients with celiac disease commonly experience the negative effects of gut dysmotility, including slowed gastric emptying, changes in small bowel transit time, and colon dysfunction.[3] Multiple mechanisms contribute to this: inflammation in the intestinal lining can damage the hormone-secreting cells that regulate digestive movement, and it can interfere with the autonomic nervous system, which controls the pace and rhythm of digestion.[4]

What this means practically is that celiac disease can throw off the gut's internal timing. And when that timing is disrupted, conditions can become favorable for bacteria to accumulate where they don’t belong, and in unusually high numbers.

When the Gluten-Free Diet Isn't Enough

The gluten-free diet is the only established treatment for celiac disease, and for the majority of patients, it works. Intestinal healing begins, inflammation decreases, and symptoms improve significantly over time.

But "the majority" isn't everyone. Research estimates that between 10% and 40% of celiac patients continue to experience gastrointestinal symptoms despite strict adherence to a gluten-free diet.[5] When that happens, clinicians sometimes refer to it as non-responsive celiac disease, defined as the persistence or recurrence of symptoms after 6 to 12 months on a carefully maintained gluten-free diet.

Research estimates that between 10% and 40% of celiac patients continue to experience gastrointestinal symptoms despite strict adherence to a gluten-free diet.

The first thing most providers and patients investigate when symptoms persist is whether gluten is still sneaking in. That's always a reasonable place to start. Cross-contamination is common, hidden gluten is easy to miss, and even small exposures can trigger a response in sensitive individuals. But accidental gluten exposure isn't the only explanation, and for some patients, it isn't the right one.

Other conditions that can look and feel like ongoing celiac symptoms include lactose intolerance, other food sensitivities, and microbial overgrowths like SIBO, IMO, and ISO. In one small, focused study that carefully confirmed both full dietary compliance and intestinal healing in symptomatic celiac patients, researchers found that SIBO was the most common identifiable cause of persistent symptoms amongst the fifteen patients studied. And when that SIBO was treated, all of them became symptom-free.[6]

Why Celiac Patients Are at Higher Risk for SIBO

To understand why celiac disease and SIBO so often show up together, it helps to understand how SIBO develops in the first place.

Your small intestine is designed to stay relatively low in bacteria. As Dr. Mark Pimentel of the MAST Program at Cedars-Sinai has described, a healthy small intestine works like a fast-moving river, keeping food and bacteria moving through before they can build up and cause problems. The gut maintains this flow through regular muscular contractions called the Migrating Motor Complex, which sweep through the small intestine approximately every 90 to 120 minutes between meals, clearing out residual bacteria. When that cleaning mechanism is disrupted, bacteria can overpopulate the small intestine, resulting in SIBO or similar microbial overgrowths.

Celiac disease is a well-documented cause of exactly that kind of disruption. Research has directly linked the gut dysmotility associated with celiac disease to an increased predisposition for bacterial overgrowth, noting that these motor disturbances can contribute both to SIBO developing in untreated patients and to symptoms persisting after starting the gluten-free diet.[7]

Celiac disease also produces measurable shifts in the gut microbiome, causing dysbiosis (imbalances in the types and numbers of microbes in the gut) and decreases in bacterial strains necessary for normal digestion. Research suggests the gluten-free diet alone (which is focusing on removing gluten, but not necessarily promoting a balanced microbiome) may not fully restore that balance for everyone.[8]

When researchers have looked at SIBO rates in celiac patients directly, the numbers tell a clear story. A 2022 systematic review and meta-analysis of 14 studies found that celiac patients had more than five times the odds of testing positive for SIBO compared to healthy controls, with a separate pooled analysis placing that risk even higher. That's not a coincidence. It's a pattern pointing to a real biological connection.[9 10]

2022 meta-analysis of 14 studies found that celiac patients had more than five times the odds of testing positive for SIBO compared to healthy controls.

SIBO, IMO, and ISO: What's the Difference?

SIBO, IMO, and ISO all fall under the broader umbrella of microbial overgrowth in the digestive tract. They involve different microorganisms and produce different gases, and those gases correlate with different symptom patterns.

This distinction matters for celiac patients specifically. Most existing studies on SIBO in celiac disease have only measured hydrogen, not methane or hydrogen sulfide.

The 2022 meta-analysis on this topic explicitly noted that by failing to measure methane, the true prevalence of microbial overgrowth in celiac patients was likely underestimated.[11] In other words, the already-elevated microbial overgrowth numbers we see in research may actually be telling only part of the story.

If you're a celiac patient with constipation that won't resolve on a gluten-free diet, IMO could be a particularly relevant piece of the puzzle. And it's one that may never have been addressed in your diagnostic journey.

Comparison table of SIBO, IMO, and ISO showing gas markers and common gut symptoms.

What Breath Testing Can Tell You

What’s the logical next step for someone with celiac disease who still has unresolved symptoms? SIBO, IMO, and ISO can be diagnosed using breath testing: a non-invasive method that measures the gases produced by microbes in your small intestine.

When microbes ferment carbohydrates, they release gases that are absorbed into the bloodstream and exhaled through your lungs. Those gases can be detected and measured in a breath sample, giving your healthcare provider real, measurable data to help diagnose and manage your condition.

The Trio-Smart 3-Gas Breath Test is the only at-home breath test that measures hydrogen, methane, and hydrogen sulfide simultaneously, so you get a complete picture of what’s going on inside your gut. It can be completed in your own home, the samples are processed by Gemelli Biotech's CLIA-certified laboratory, and the results are delivered right to your phone.

For celiac patients who are already carrying the weight of a demanding diagnosis and a restrictive diet, having access to this kind of testing without waiting for another doctor’s appointment or having another invasive procedure can be a huge relief.

There are medications, therapies, diets, and management strategies available to patients with SIBO, IMO, and ISO. With your results in hand, you and your healthcare team can make a more informed decision about what treatment or management options are appropriate for you.

If you're not sure whether breath testing makes sense for your situation, you can take our short quiz to get a better sense of whether microbial overgrowth could be a factor in what you're experiencing.

What’s Your Next Step?

Persistent gut symptoms in someone who is carefully following a gluten-free diet deserve a closer look. The symptoms of celiac disease and microbial overgrowth overlap so much that it's easy for patients and providers to keep attributing unresolved symptoms to gluten when something else may be driving them.

The research offers a reason for optimism here. In a 2022 meta-analysis, 95.6% of celiac patients who tested positive for SIBO and received antibiotic treatment reported meaningful improvement or normalization of their gut symptoms. That's not a small finding. For patients who had been struggling despite doing everything right on their diet, identifying and treating a co-occurring microbial overgrowth made a real difference.

If you haven't explored possibilities beyond gluten yet, it may be worth investigating and testing for microbial overgrowths like SIBO, IMO and ISO.

Frequently Asked Questions

Can celiac disease cause bloating even on a gluten-free diet?

Yes. While the gluten-free diet typically reduces intestinal inflammation and helps symptoms improve, a meaningful subset of celiac patients continue to experience bloating even on a strict diet. Possible explanations include accidental gluten exposure, lactose intolerance, other food sensitivities, and microbial overgrowths like SIBO or IMO.

Can celiac disease cause diarrhea?

Yes. Chronic diarrhea is one of the hallmark symptoms of untreated celiac disease. When diarrhea continues after going gluten-free, it may point to ongoing intestinal damage, an unrelated food sensitivity, or an underlying condition like SIBO or ISO.

Can celiac disease cause constipation?

Yes. Although diarrhea is more classically associated with celiac disease, constipation can also occur and persist on a gluten-free diet. Celiac disease disrupts gut motility in ways that can slow intestinal transit. IMO, which is associated with constipation and not always identified, may also be a contributing factor in some patients.

Does gluten cause bloating?

In people with celiac disease, yes, gluten triggers an immune response that damages the gut lining and can cause significant bloating. But bloating that continues on a gluten-free diet may have other causes, including microbial overgrowth in the small intestine.

What is non-responsive celiac disease?

Non-responsive celiac disease refers to the persistence or recurrence of celiac symptoms after 6 to 12 months on a strict gluten-free diet. Common causes include continued gluten exposure, lactose intolerance, other food sensitivities, refractory celiac disease, and other conditions such as SIBO.

Is it IBS or celiac disease?

IBS and celiac disease share many overlapping symptoms like abdominal pain, bloating, gas, diarrhea, and constipation, and they can occur together. SIBO has also been found at elevated rates in both populations. A clinical evaluation that includes celiac antibody testing, and potentially breath testing for microbial overgrowth, can help clarify what's actually driving your symptoms.

What is the connection between SIBO and celiac disease?

Celiac disease impairs gut motility and disrupts the microbiome in ways that create favorable conditions for bacterial overgrowth in the small intestine. Multiple studies have found that celiac patients face significantly higher rates of SIBO than the general population. Treating SIBO in symptomatic celiac patients often leads to meaningful symptom improvement.

Should I get a breath test if I have celiac disease and ongoing gut symptoms?

If you have celiac disease, you're following the gluten-free diet carefully, and you're still experiencing gut symptoms, a breath test for SIBO, IMO, and ISO is worth investigating and/or discussing with your healthcare provider. It's non-invasive, can be completed at home, and can provide clinically useful information about whether microbial overgrowth is contributing to how you feel.