diarrhea

Hydrogen Dominant SIBO vs Methane or Hydrogen Sulfide?

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2025 Updated version

Understanding the key differences between hydrogen-dominant SIBO vs. methanogens and hydrogen sulfide

If you've been struggling with chronic bloating, unpredictable bowel movements, and a gut that seems to react to every food, you're not alone. Millions of people struggle with mysterious gut symptoms that don't improve with generic advice of eating more fiber or taking probiotics.

It might be that you are already diagnosed with IBS (Irritable Bowel Syndrome), but you know there is something deeper going on, and you don't want to accept IBS as a life sentence, as you shouldn't.

Chances are you've come across the term SIBO or Small Intestinal Bacterial Overgrowth.

SIBO isn't just one condition. It's a spectrum of imbalances, each with distinct causes, symptoms, and treatment responses. I've seen firsthand how identifying the type of SIBO someone has is the game-changing first step in actually getting better.

In this post, I'll break down the three main types of SIBO:

  • Hydrogen-dominant SIBO
  • Methane-dominant overgrowth/methanogens (now more accurately termed IMO, or Intestinal Methanogen Overgrowth)
  • Hydrogen sulfide-dominant SIBO (which is now named ISO, Intestinal Sulfide Overproduction)

I'll go over their differences in symptoms, underlying microbes, testing options, and treatment strategies so you can feel empowered to take the next right step on your gut healing journey.

What is SIBO?

SIBO occurs when bacteria (or archaea, more on that in a second) start growing excessively in the small intestine. This region of the gut isn't built to handle large populations of gas-producing microbes. When overgrowth occurs, those microbes ferment carbohydrates and fibers in your food, producing gas byproducts.

These gases—hydrogen, methane, or hydrogen sulfide—can inflame the intestinal lining, trigger food sensitivities, and slow or speed up gut motility. (1)

But the type of gas produced gives us important clues about:

  • What symptoms you're likely to experience
  • Which organisms are overgrowing
  • How best to test and treat

Let's break down the three subtypes.

 

Hydrogen-dominant SIBO

Hydrogen-dominant SIBO is the most commonly diagnosed form. It's caused by an overgrowth of two predominantly Proteobacteria species: Klebsiella pneumoniae and Escherichia coli, which can comprise 46% of the duodenal microbiome in SIBO cases, while Firmicutes are decreased. These bacteria ferment carbs and produce hydrogen gas as a byproduct. (2)

So the species associated with SIBO are:

  • Escherichia coli
  • Streptococcus spp.
  • Klebsiella
  • Enterococcus
  • Bacteroides,
  • Staphylococcus,
  • Clostridium,
  • Peptostreptococcus (3)

Hydrogen isn't inherently toxic, but when it's produced in excess in the small intestine, it can disrupt normal digestion and trigger diarrhea, bloating, and abdominal cramping. Studies confirm that hydrogen-dominant SIBO is specifically linked to IBS-D (diarrhea-predominant type). (4)

Hydrogen levels can also be consumed by methanogens (producing methane) or sulfate-reducing bacteria (producing hydrogen sulfide), which is why measuring hydrogen alone may not fully reflect the extent of hydrogen-producing bacteria. (2)

The most common symptoms of the hydrogen-dominant SIBO (5) are:

  • Diarrhea or loose stools,
  • Abdominal cramping, pain,
  • Frequent bloating or visible distension,
  • Belching or flatulence,
  • Fatigue and brain fog,
  • Weight loss,
  • food sensitivities, especially to fermentable carbohydrates (FODMAPs) or high-fiber foods.

Hydrogen-dominant SIBO is often associated with faster intestinal transit and diarrhea. Excess bacterial fermentation in the small intestine increases osmotic load and irritates the mucosa, which can accelerate motility and reduce nutrient absorption.

This malabsorption and ongoing immune/gut–brain activation may contribute to fatigue, brain fog, and increased food sensitivities in some patients, underscoring that these are downstream effects of maldigestion/malabsorption and gut–brain interactions.

Symptom severity in hydrogen-dominant SIBO often depends on underlying motility disorders (e.g., impaired migrating motor complex), structural issues, and coexisting IBS, not just the gas profile.​

Addressing root causes (gut motility, diet, nervous system, and micronutrient status) is important to prevent relapse. (6)

 

How do we test for hydrogen-dominant SIBO?

The most commonly used non-invasive test is the 3-hour lactulose or glucose breath test. This test measures hydrogen and methane gas levels in the breath at regular intervals after ingestion of a sugar substrate. (7)

The North American consensus defines a positive SIBO breath test as a rise of 20 parts per million (ppm) or more of hydrogen within the first 90 minutes. (8)

Breath testing is a helpful diagnostic tool, but not perfect. Many factors may influence the accuracy of the test results:

  • Preparation mistakes (not following the prep diet before testing) (9)
  • Mistakes during performing the test (9)
  • Rapid transit time (false positives) (10)
  • Poor oral hygiene
  • Carbohydrate malabsorption (11)
  • Individual differences in substrate metabolism, colonic fermentation (11)

Some people with hydrogen-dominant SIBO may also have "flatline" results if hydrogen is rapidly converted to other gases (such as methane or hydrogen sulfide), which is why multi-gas testing and clinical context always matter. (12)

Treatment options for hydrogen-dominant SIBO

Conventional treatment:

  • Rifaximin (Xifaxan) – a non-systemic antibiotic that targets the small intestine with minimal effect on the rest of the body. Often used for 2–4 weeks. (13) However, relapse is common, and underlying motility and dietary factors must be addressed. (14)

Commonly used herbal antimicrobials:

  • Berberine-containing herbs
  • Oregano oil
  • Neem

One study in Global Advances in Health and Medicine (2014) found that herbal therapy was as effective as Rifaximin in eradicating SIBO. (15)

Elemental diet:

This is a short-term liquid nutrition protocol that starves bacteria while nourishing the host. It can be very effective (up to an 85% success rate in hydrogen SIBO when used for 3 weeks) and is especially useful for those with severe symptoms or treatment resistance. (16)

It may be most useful for:

  • Patients with severe symptoms and high gas levels
  • Those who haven't responded to herbs or antibiotics
  • Those with multiple gas types or relapsing SIBO
SIBO types, Hydrogen-Dominant SIBO vs Methane or Hydrogen Sulfide

Intestinal Methanogen Overgrowth (IMO)

Here's where it gets interesting: methane overgrowth isn't technically caused by bacteria; it's caused by methanogenic archaea, particularly Methanobrevibacter smithii (or other methanogens). (17)

Unlike hydrogen SIBO, which involves bacteria, methanogen overgrowth reflects a shift in the overall gut ecosystem. It is sometimes seen in cases with higher Firmicutes and lower Bacteroidetes ratios on stool testing.

Methanogens consume hydrogen and carbon dioxide to produce methane and often coexist with hydrogen-producing bacteria, creating mixed-gas patterns.

Common symptoms associated with methanogen overgrowth (18):

  • Chronic constipation
  • Incomplete bowel movements
  • Weight gain
  • Gas, bloating, and sluggish digestion
  • Nausea and early satiety
  • Reflux symptoms (heartburn)

Methane slows gut motility, the way the food passes through the intestines, and can disrupt normal peristalsis, contributing to constipation and sometimes a sense of incomplete evacuation. It has also been associated with IBS-C (constipation-predominant IBS). (19)

Some experimental research suggests that methane may have anti-inflammatory or antioxidant properties (20), leading to the hypothesis that methane-dominant patients may experience fewer overt food reactions than hydrogen-dominant patients.

On the flip side, methanogen patients respond to treatment much more slowly and often require longer treatment timelines.

How to test for methane overgrowth

Same as hydrogen: via the breath test. A methane level ≥10 ppm at any point is considered a positive result. (8)

In some cases, stool PCR tests like GI-MAP can sometimes reveal methanogen overgrowth when breath tests are negative or inconclusive.

Treatment options for methanogen overgrowth

Conventional approach:

  • Rifaximin + Neomycin (or Metronidazole) – combo therapy shown to be more effective than monotherapy. (21)

Natural alternatives:

  • Atrantil – blend of peppermint, quebracho, and horse chestnut extract
  • Allicin (stabilized garlic)
  • Berberine
  • Neem
  • Oregano oil

Methane overgrowth typically responds more slowly to treatment than hydrogen SIBO. Patients may need 8–12 weeks of antimicrobial protocols, sometimes in repeated cycles, and are more likely to benefit from prokinetic support during and after treatment to prevent relapse.

Intestinal Sulfide Overproduction (ISO)

Formerly known as "hydrogen sulfide SIBO," ISO reflects an overproduction of hydrogen sulfide gas, commonly caused by sulfur-reducing bacteria such as Desulfovibrio spp. and Bilophila wadsworthia. These microbes use hydrogen and sulfur-containing compounds to generate hydrogen sulfide, which can be toxic at high levels. (22)

Common symptoms include (23):

  • Flatulence, often with rotten egg–smelling gas or stools (although this is not always present)
  • Diarrhea or alternating diarrhea and constipation
  • Belching
  • Abdominal pain
  • Nausea, fatigue, headaches
  • Joint or bladder pain
  • Food sensitivities, especially to sulfur-containing foods

Many ISO patients often feel worse with protein-rich foods, high-sulfur foods (e.g., eggs, garlic, onions, brassicas), and may react negatively to herbs such as Allicin (garlic extract) or sulfur‑donating supplements (NAC, glucosamine, MSM, glutathione).

Hydrogen sulfide in small amounts is used by the body for signaling and vascular function, but in excess, it becomes toxic to epithelial cells. ISO is also associated with symptoms beyond digestion, such as fatigue, brain fog, bladder irritation, and systemic inflammation.

In chronic or treatment-resistant cases of ISO, excess hydrogen sulfide may impair mitochondrial function, increase oxidative stress, and damage the gut lining, creating a vicious cycle where healing becomes difficult without addressing deeper sulfur detoxification pathways and redox balance. (24) It's not just about "too many bacteria",  it's also about an inflamed, disrupted mucosal and redox environment that encourages sulfur-reducing microbes like Desulfovibrio to thrive.

How to test for hydrogen sulfide

H2S SIBO is not reliably detected by standard breath tests, making diagnosis tricky.

The only test that can detect hydrogen, methane, and hydrogen sulfide is the TrioSmart test, which is currently only available in the USA.

In the absence of the TrioSmart test, if you have used the standard 3-hour breath test and the result shows a flatline (little to no rise in hydrogen or methane since H₂S producers can consume hydrogen and keep measured hydrogen low), and you also have the typical symptoms, then hydrogen sulfide-dominant SIBO can be suspected. (25)

However, while a flatline on a breath test can point toward ISO, recent research suggests this isn't always the case. Some hydrogen sulfide producers still show hydrogen spikes, while others may not produce enough gas to be detected. A flatline result may also reflect issues with gas diffusion or absorption. (7) Following up with a stool test can also be helpful.

TrioSmart test result pattern

TrioSmart breath test sample indicating Intestinal Methanogenic Overgrowth

Treatment for H2S SIBO

Because of its toxicity and complexity, treatment should be approached carefully.

Conventional approach:

  • Bismuth (to bind and reduce hydrogen sulfide)+ Rifaximin + Metronidazole – combo therapy helps bind hydrogen sulfide and reduce microbial load. (23).

Nutritional strategies:

  • Short-term low-sulfur diet: reducing high-sulfur foods like eggs, cruciferous vegetables, garlic, onions, and red meat.
  • Targeted cofactors: molybdenum and vitamin B6 are cofactors to support sulfur metabolism and transsulfuration pathways.

For more details, check out my previous post on Hydrogen Sulfide SIBO.

Mixed type of SIBO: when two (or all three) gases coexist

It's possible and common to have more than one gas present simultaneously.

For example:

  • Hydrogen + methane is extremely common, since methanogens need hydrogen.
  • Hydrogen + hydrogen sulfide often co-occur due to substrate sharing.

In these cases, treatment plans must address both organisms and carefully sequence therapies.

Choosing the right treatment approach

Choosing between antibiotics, herbal antimicrobials, or the elemental diet depends on:

  • Gas type(s)
  • Severity of symptoms
  • Coexisting conditions (e.g., Candida, parasites, mold toxicity)
  • Personal preferences and medication tolerance

How each gas affects gut motility and digestion

Understanding how each gas affects gut motility helps explain why symptoms and treatment responses vary:

  • Hydrogen: increased intestinal transit and looser stools, which helps explain diarrhea-predominant presentations in many hydrogen-dominant cases.
  • Methane: Slows motility significantly, contributing to constipation, gas retention, and a feeling of incomplete evacuation.
  • Hydrogen sulfide / ISO: Acts as a biphasic regulator of gut function. At physiological levels, it supports normal motility and mucosal signaling, but in excess, it can disrupt motility patterns, impair epithelial energy metabolism, and damage the gut lining.

Because all three gas patterns are closely linked to gut motility disturbances, targeted antimicrobial treatment is often followed by prokinetic and motility-supportive strategies to maintain results and reduce relapse risk.

Knowing your SIBO type is the first step to healing

If you're still guessing whether you have hydrogen-dominant SIBO or something else, don't. Proper, thorough testing is key to finding a treatment that actually works.

I've worked with many clients who were labeled with "IBS" for years before identifying their SIBO type and finally getting relief. Your healing path depends on personalized care, clear diagnostics, and a step-by-step strategy.

Dealing with SIBO requires a holistic approach, supplements and sometimes medication, and customized nutrition and lifestyle changes.

I know from my own experience that SIBO can be a super frustrating condition and, in some cases, may require a longer journey, but it is possible to get rid of it as I did.

 

* This post is for informational purposes only and not intended to diagnose, treat, or cure any medical condition. Please consult your healthcare provider before making any medical or dietary changes.

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SIBO vs Celiac Disease: symptoms, diagnosis, and the critical connection you need to know

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If you've ever struggled with chronic gut issues like bloating, gassiness, diarrhea, or fatigue, you know how life-altering they can be. The daily discomfort, restrictive diets, and constant anxiety about flare-ups can take a toll on both your physical and emotional well-being.

Among the myriad of gut health conditions, SIBO (Small Intestinal Bacterial Overgrowth) and celiac disease often cause confusion due to their overlapping symptoms.

Despite their similarities, these conditions have very different causes, diagnostic criteria, and treatments.

In this blog, I'll break down what SIBO vs Celiac disease is, how to tell them apart, and explore their surprising connection. Plus, I'll share the inspiring story of a client who found answers and relief after years of struggle.

SIBO vs Celiac disease main differences and similarities

What is SIBO?

Let's start with the basics. Small Intestinal Bacterial Overgrowth (SIBO) occurs when bacteria that normally live in other parts of the digestive tract—like the colon—start to overpopulate the small intestine. This imbalance can wreak havoc on your digestive system and lead to a range of debilitating symptoms, including:

  • Persistent bloating and gas
  • Abdominal pain or discomfort
  • Diarrhea, constipation, or alternating between the two
  • Fatigue and brain fog, often caused by nutrient malabsorption
  • Food intolerances, particularly to fermentable carbohydrates (like those found in FODMAP foods)

Living with SIBO can feel like being in an endless cycle of discomfort. You might wake up feeling "off," brace yourself for every meal, and wonder why seemingly healthy foods like cauliflower or garlic leave you doubled over with pain. For many, the restrictive diets they turn to for symptom relief can feel isolating and unsustainable.

But why does SIBO happen in the first place? Causes vary but often include:

  • Impaired gut motility (sometimes due to post-infectious IBS or conditions like diabetes)
  • Structural abnormalities (like adhesions or scar tissue from surgeries or existing conditions like Endometriosis)
  • Usage of certain medications, such as proton pump inhibitors (PPIs), which reduce stomach acid and can disrupt gut bacteria
  • Lack of defense mechanisms in the body to prevent overgrowth (low stomach acid, poor bile flow, immune dysregulation, etc.)

If left untreated, SIBO can lead to long-term nutrient deficiencies, particularly in B12, iron, and fat-soluble vitamins. Thus, early diagnosis and treatment are crucial for improving quality of life.

What is Celiac Disease?

Unlike SIBO, celiac disease is an autoimmune condition.

It's triggered when the immune system mistakenly attacks the lining of the small intestine after consuming gluten—a protein found in wheat, barley, and rye. This immune response damages the intestinal lining (the villi) in your small intestine, leading to inflammation and impaired nutrient absorption.

Common symptoms of celiac disease include:

  • Chronic diarrhea or constipation
  • Abdominal pain and bloating
  • Fatigue and brain fog
  • Unexplained weight loss or difficulty maintaining a healthy weight
  • Signs of malnutrition, such as anemia, brittle nails, or thinning hair

However, not everyone with celiac disease experiences obvious digestive symptoms.

Some people may struggle with "non-classical" symptoms, like joint pain, migraines, depression, or infertility. This wide range of manifestations often makes celiac disease difficult to diagnose, with many individuals going years—if not decades—without answers.

What makes celiac disease particularly challenging is its lifelong nature. Gluten exposure, even in small amounts like just a crumb, can reignite the immune response, which damages the intestinal lining (the villi), impairing the body's ability to absorb nutrients. This requires not just dietary changes but a complete lifestyle shift to avoid cross-contamination in food, cookware, and even cosmetics.

What is gluten?

Gluten is a type of protein found naturally in certain grains, including:

  • Wheat (found in bread, pasta, baked goods)
  • Barley (used in malt products, beer, and soups)
  • Rye (commonly in rye bread and cereals)
  • Triticale (a hybrid of wheat and rye).

Gluten acts as a "glue" that holds food together, giving dough its elasticity and helping it maintain its shape. This is why gluten is so crucial in baking—it gives bread that soft, chewy texture we all recognize.

Beyond obvious foods like bread and pasta, gluten is found in many unsuspecting products, including:

  • Sauces and dressings (soy sauce, gravies)
  • Processed snacks and candy
  • Soups and broths
  • Beer and malt beverages
  • Personal care products (lip balms, shampoos)

Even small amounts of gluten, such as cross-contamination from shared cooking surfaces or utensils, can trigger symptoms in individuals with celiac disease. This is why strict gluten avoidance is necessary for recovery.

For those without celiac disease but with gluten sensitivity (non-celiac gluten sensitivity, NCGS) or other gut issues, gluten can still cause bloating, fatigue, and inflammation. Understanding gluten and its impact is key to managing symptoms and supporting gut health.

Similarities between SIBO and Celiac Disease

It's easy to see why SIBO and celiac disease are often confused.

Both conditions can cause damage to the small intestine or disrupt its functionality. Therefore, both of them share similar symptoms, such as chronic bloating, diarrhea, fatigue, and other discomforts that disrupt daily life.

People with either condition might find themselves misdiagnosed with IBS (irritable bowel syndrome) or dismissed altogether, leaving them frustrated and desperate for answers.

Here's where the overlap happens:

  1. Digestive distress: Both SIBO and celiac disease can lead to bloating, abdominal pain, and irregular bowel movements. These symptoms often worsen after eating, making it difficult to pinpoint specific triggers.
  2. Nutrient deficiencies: Malabsorption is a hallmark of both conditions. In SIBO, bacterial overgrowth can "steal" nutrients from your food before your body has a chance to absorb them. In celiac disease, intestinal damage hinders the absorption of critical nutrients like iron and calcium.
  3. Fatigue and brain fog: Whether caused by nutrient deficiencies or systemic inflammation, both conditions can leave you feeling drained and unfocused, affecting your ability to work, socialize, or even enjoy daily activities.
  4. Emotional impact: Living with unexplained symptoms can feel isolating and stressful. Both conditions are known to take a toll on mental health, with many sufferers experiencing anxiety, depression, or a sense of hopelessness.

However, the similarities end there. While SIBO is fundamentally a bacterial imbalance, celiac disease involves an autoimmune reaction to gluten. This distinction is key to understanding how each condition is diagnosed and treated.

SIBO and Celiac disease symptoms

Key differences between SIBO and Celiac Disease

While SIBO and celiac disease share similar symptoms, their underlying causes and diagnostic approaches are entirely different. Here's a breakdown of the key differences:

Mechanisms:

    • SIBO: A bacterial imbalance caused by an overgrowth of microbes in the small intestine.
    • Celiac disease: An autoimmune condition where the body attacks the small intestine in response to gluten.

Triggers:

    • SIBO: This can be caused by poor gut motility, structural abnormalities, reduced protective mechanisms, or the use of medications. It's often exacerbated by carbohydrate-heavy meals – even on a gluten-free diet, which feed the overgrown bacteria.
    • Celiac disease: Triggered by consuming gluten, which is found in wheat, barley, rye, and certain processed foods. It's also common to have a negative response to dairy and soy due to cross-reactions.

Markers:

    • SIBO: Diagnosed through breath tests or, in rare cases, small intestine aspirates.
    • Celiac disease: Identified via blood tests (tTG-IgA, DGP), intestinal biopsy, and genetic testing. In some cases, a comprehensive stool test can also indicate reactions to gluten (but doesn't equal a diagnostic tool).

Understanding these differences is essential for pinpointing the right diagnosis and creating an effective treatment plan.

Diagnostic criteria and tools

Diagnosing SIBO

The gold standard for diagnosing SIBO is the lactulose or glucose breath test, which measures hydrogen and methane gases produced by bacteria and archaea in the small intestine. (If you live in the USA, the TrioSmart test can also measure hydrogen sulfide gas production.) Elevated levels of these gases after consuming a sugar solution indicate bacterial overgrowth or Intestinal Methanogen Overgrowth (IMO).

However, it's important to be aware that breath tests can sometimes produce false positives or negatives. So, it's important to evaluate symptoms and medical history in conjunction with test results to arrive at the right conclusion.

Diagnosing Celiac Disease

Diagnosing celiac disease requires a multi-step approach:

  1. Blood tests: Screening tests, such as tissue transglutaminase (tTG-IgA) or deamidated gliadin peptide (DGP), are the first step.
  2. Intestinal biopsy: If blood tests are positive, a biopsy of the small intestine confirms the diagnosis by identifying villous atrophy (damage to the gut lining). The patient needs to consume gluten before performing this type of test.
  3. Genetic testing: In ambiguous cases, the HLA-DQ2 and HLA-DQ8 genes are often tested to rule out celiac disease. While these genes are not diagnostic, their absence makes celiac disease very unlikely.

The SIBO-Celiac Disease connection

Did you know that celiac disease can predispose you to SIBO?

Here's how the two conditions are linked:

  • Intestinal damage: In celiac disease, chronic inflammation can damage the small intestine, leading to impaired motility and an environment conducive to bacterial overgrowth.
  • Nutrient deficiencies: A lack of nutrients like zinc and magnesium, often seen in celiac disease, can hinder gut healing and motility.
  • Delayed diagnosis: Undiagnosed or untreated celiac disease increases the risk of developing SIBO due to prolonged intestinal damage.

A 2019 study published in Gut found that individuals with celiac disease are significantly more likely to develop SIBO compared to the general population. This highlights the importance of testing for both conditions if symptoms persist after adopting a gluten-free diet.

SIBO and Celiac disease connection

Treatment for Celiac Disease

The cornerstone of treating celiac disease is a strict lifelong gluten-free diet, which allows the gut lining to heal and inflammation to subside.

Here's a closer look at the process:

  1. Eliminating gluten: Even trace amounts of gluten from cross-contamination can trigger a reaction. This requires diligence when dining out, shopping for groceries, and preparing meals at home.
  2. Healing the gut: Anti-inflammatory foods, bone broth, and supplements like L-glutamine and zinc can support gut repair.
  3. Managing nutrient deficiencies: Many people with celiac disease require supplementation for iron, B12, and fat-soluble vitamins to restore optimal levels.

Holistic approach toward SIBO with Celiac Disease

If you're dealing with SIBO and celiac disease, a one-size-fits-all treatment plan won't work. A functional, holistic approach is key to addressing both conditions simultaneously.

Steps to address SIBO:

  1. Boosting gut motility: Prokinetics, such as ginger or motility agents (natural or pharmaceutical), can prevent bacterial stagnation in the small intestine.
  2. Reducing the overgrowth: Antimicrobial herbs (e.g., berberine, oregano oil) or prescription antibiotics (like rifaximin) may be used to reduce bacterial load.
  3. Supporting the gut microbiome: Managing SIBO doesn't just stop with an elimination protocol. Prebiotics and probiotics tailored to individual needs help restore balance without worsening symptoms.
  4. Dietary adjustments: A low-FODMAP diet is often used temporarily to reduce symptoms while treating the root causes. However, it is also important to incorporate anti-inflammatory nutrients such as omega-3 fatty acids, turmeric, and polyphenol-rich foods, as these can reduce inflammation and support healing.
  5. Lifestyle changes:
    • Stress impacts the gut-brain axis, worsening symptoms. Incorporating stress-relief techniques like mindfulness, yoga, or deep breathing can support healing.
    • Quality sleep promotes gut motility and overall healing. Aim for 7-9 hours per night.
    • Gentle exercise, such as walking, yoga, or Pilates, improves gut motility and reduces stress.
    • Slowing down at meals, chewing thoroughly, and creating a calm eating environment can improve digestion and reduce bloating.
  1. Enzymatic support: Digestive enzymes and bitters can aid nutrient absorption.
  2. Detox pathways: Enhancing liver function with cruciferous vegetables, dandelion tea, or milk thistle can support overall healing.

Addressing both conditions in tandem can improve symptoms, restore balance, and reclaim quality of life.

A case study

When one of my clients first came to me, she was struggling with constant bloating, fatigue, and a restricted diet that felt impossible to manage.

After performing a comprehensive stool test (GI MAP), several red flags were showing up:

  • Inadequate production of digestive enzymes
  • Impaired detoxification
  • Possible signs of intestinal bleeding
  • signs of intestinal inflammation
  • immune system activation and a potential gluten sensitivity
  • Increased risk for an increased intestinal permeability ("leaky gut")

 

Client case Celiac disease

I referred the client to a gastroenterologist for further evaluation, which confirmed a diagnosis of celiac disease. In her case, no SIBO was detected.

From there, we developed a personalized protocol that included:

  • Transitioning to a strict gluten-free diet to avoid triggering immune responses
  • Supporting gut motility to prevent bacterial overgrowth
  • Boosting digestive enzyme production
  • Incorporating anti-inflammatory nutrients and a fiber-rich diet to support the growth of beneficial bacteria, which were also low on her test
  • Supporting the detoxification pathways

Within six months, the client reported feeling more energetic, less bloated, and more in control of her life. As she put it, "Working with Alexandra finally gave me answers to why I was feeling so bloated, tired, irritated, and gassy...She helped me get to the root causes of all my symptoms."

Conclusion

SIBO and celiac disease may look similar on the surface, but their causes, diagnostic criteria, and treatments are entirely different. Understanding these differences—and their potential connection—can help you get the right diagnosis and embark on a path to healing.

If you're struggling with persistent gut issues, don't settle for temporary solutions. A holistic approach that addresses the root causes of your symptoms can help you reclaim your life. Remember, with the right tools, support, and mindset, healing is within reach!

This post is only for informational purposes and is not meant to diagnose, treat, or cure any disease. I recommend always consulting your healthcare practitioner before trying any treatment or dietary changes.

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SIBO vs IBS: Key Differences, Symptoms, and Treatments Explained

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You're tired. You are tired of feeling bloated, tired of not knowing what's causing that constant discomfort, and tired of trying new diets only to see little or no improvement. Sound familiar?

If you've been stuck in this cycle of gastrointestinal turmoil, you've likely come across two terms: SIBO (aka Small Intestinal Bacterial Overgrowth) and IBS (Irritable Bowel Syndrome). They're often confused with one another, and it's easy to see why: both conditions involve gut issues, and the symptoms can feel like a constant guessing game.

So, how can you tell if it's SIBO or IBS that's wreaking havoc in your gut?

In this blog post, we'll dive into the differences and similarities between these two conditions—SIBO vs IBS—so you can better understand your symptoms, seek the right diagnosis, and find the treatment that finally brings relief. We'll also look into why IBS often gets criticized as a "catch-all" label and how you can advocate for a better understanding of your gut health.

What is SIBO?

Small Intestinal Bacterial Overgrowth (SIBO) is a condition in which an excessive amount or abnormal type of bacteria are present in the small intestine, where their numbers should be relatively low compared to the large intestine.

See, your small intestine isn’t meant to host a large number of bacteria—that’s more the colon’s job. Your colon is the place where you can find the gut microbiome (a community of trillions of microorganisms).

In SIBO, bacteria that should stay in the large intestine migrate up into the small intestine, causing interference with normal digestion and absorption of food by fermenting carbohydrates and fibers and creating gases (methane, hydrogen, hydrogen sulfide).

How does it feel to live with SIBO?

Imagine having too many guests at a dinner party: there’s no room to breathe, everyone’s stepping on each other’s toes, and nothing works as it should.

This overcrowding leads to the fermentation of your food in the wrong part of the gut, resulting in:

  • Chronic bloating that tends to get worse as the day goes by,
  • Changed bowel movements involving constipation and/or diarrhea or alternating bowel movements,
  • Abdominal pain,
  • Nausea,
  • Burping,
  • Fatigue,
  • Brain fog,
  • Muscle or joint pain,
  • Skin issues (acne, rosacea, eczema)
  • Unexplained weight loss or weight gain,

But it can also impact other areas of the body. (1)

Interestingly, SIBO often follows another gut-altering event, like food poisoning or surgery, which disrupts the balance of your gut bacteria. Fibers and probiotics—usually gut heroes—can worsen the condition by providing extra fuel for the overgrown bacteria to feast on.

What is IBS?

Did you know that more than 60 million people have Irritable Bowel Syndrome (IBS), and 70% of them are women? (2)

IBS is a bit more elusive. It’s a functional GI condition defined by a collection of chronic gut symptoms, but there’s no clear-cut cause, making it somewhat of a medical mystery.

IBS is commonly diagnosed based on a specific set of criteria known as the Rome IV Criteria, which include recurrent symptoms like abdominal pain, bloating, constipation, diarrhea, or a combination of both, for at least three months. (3)

How does it feel to have IBS?

Imagine being in a car with a faulty GPS—some days, you might end up at your destination, but other days, you’re stuck in traffic or stranded on a dead-end street. IBS feels like that: the gut’s regular motility goes haywire, leading to unpredictable and uncomfortable outcomes.

The brain-gut connection plays a big role in IBS, with stress and heightened sensory responses making symptoms worse. (4)

IBS is categorized by the following categories:

  • IBS with predominant constipation (IBS-C)
  • IBS with predominant diarrhea (IBS-D)
  • IBS with mixed bowel habits (IBS-M)

SIBO vs IBS: similarities and differences

At first glance, SIBO and IBS seem similar —both share many of the same symptoms, which can make it difficult to tell them apart.

However, a closer look reveals important distinctions in the underlying mechanisms, as well as how the symptoms manifest.

Symptom overlap

When comparing SIBO vs IBS, the overlap in symptoms is undeniable.

Both conditions can cause:

  • Bloating
  • Abdominal pain, cramping
  • Constipation and/or diarrhea
  • Fatigue
  • Food intolerances

However, the way these symptoms manifest differs between the two conditions.

For example, in SIBO, there are a few tell signs, like bloating, which tends to worsen as the day progresses, and meals rich in fiber or taking probiotics can exacerbate the discomfort.

In contrast, bloating in IBS can happen at any time, and fiber is often recommended as a helpful addition.

SIBO vs IBS Key Differences, Symptoms

Main differences

Causes:

While multiple factors influence both SIBO and IBS, SIBO is specifically characterized by bacterial overgrowth in the small intestine, where these microbes shouldn't be present in large numbers. This overgrowth leads to the fermentation of undigested food, which causes gas, bloating, and discomfort.

However, the underlying reasons for SIBO can also be many things, from impaired gut motility through infections to structural problems.

IBS, on the other hand, is more ambiguous. In contrast, IBS is more of a functional gastrointestinal disorder—it involves issues with how the gut functions rather than an actual bacterial overgrowth in a specific area.

IBS can be driven by many causes, such as gut-brain axis dysfunction, hypersensitivity of the gut, altered motility, and even imbalances in the gut microbiome (known as dysbiosis), without necessarily involving bacterial overgrowth in the small intestine.

However, it is important to mention that studies show up to 80% of IBS cases may, in fact, be related to SIBO. (5)

This suggests that, in many cases, SIBO might be an underlying cause of IBS symptoms. However, it's important to remember that not all IBS cases are caused by SIBO.

Diagnosis:

SIBO is commonly diagnosed using a lactulose or glucose breath test (link to breath test blog), which measures the gases (hydrogen, methane, and, in some cases, hydrogen sulfide) produced by bacteria or archaea in your small intestine. A positive test result confirms not just SIBO but it helps determine the level of overgrowth and the type of SIBO.

IBS, on the other hand, is often diagnosed by exclusion after ruling out other conditions, which can be frustrating for many patients. The Rome IV Criteria help guide the diagnosis, and patients are typically diagnosed based on symptoms that have been present for at least three months. IBS may also require stool tests or colonoscopies to rule out conditions like inflammatory bowel disease or celiac disease.

However, there is also a diagnostic test for certain people with IBS. The IBS-Smart test is available on the market to diagnose IBS with predominant diarrhea (IBS-D) and mixed symptoms (IBS-M).

This blood testing looks for anti-CdtB and anti-vinculin antibodies, the markers of a food poisoning event. These antibodies can attack the gut's nerves and impair the gut's cleaning wave. (6)

Nutrient absorption:

SIBO can interfere with nutrient absorption, leading to deficiencies in vitamins and minerals (especially deficiency in fat-soluble vitamins such as Vitamin A, D, and E, and also negatively impacting vitamin B12 and iron levels) (7).

In contrast, nutrient absorption in IBS is generally normal unless it's combined with another condition like celiac disease.

Probiotic response:

Another major difference is how each condition responds to probiotics and dietary fibers. Probiotics, often touted as a gut health remedy, may worsen symptoms of SIBO. This is because the overgrown bacteria feed on these probiotics, leading to more gas and bloating.

In contrast, many people with IBS can benefit from the right probiotics or fiber supplements.

Let’s look at the treatment options: SIBO vs IBS

The treatment plans for SIBO vs IBS vary significantly, largely because the causes of each condition are so different.

Treating SIBO

Treatment for SIBO primarily focuses on reducing bacterial overgrowth and addressing underlying causes like gut motility issues.

The main strategies include:

  • Antibiotics or antimicrobials: Common treatments include rifaximin, often combined with another antibiotic (in case of methane and hydrogen sulfide gas), or herbal antimicrobials that target bacterial overgrowth in the small intestine. (1)
  • Dietary changes: Many people with SIBO find relief through a certain SIBO diet, such as the low-FODMAP diet, SIBO Bi-phasic, or the low fermentation diet, which restrict the types of carbohydrates that can fuel bacterial overgrowth.
  • Prokinetics: These are medications or supplements that help improve gut motility and prevent bacteria from lingering in the small intestine.
  • Post-treatment care: Relapse is fairly common with SIBO, unfortunately. Studies show that about 45% of patients experience recurrence after antibiotic treatment (8), so long-term care might involve dietary and lifestyle changes and addressing the root causes.

Read the complete guide on how to heal your gut from SIBO with a natural approach. 

Treating IBS

Treatment for IBS is often more varied and personalized since its exact cause isn’t clear-cut.

Options include:

  • Dietary adjustments: The low-FODMAP diet is also commonly recommended for IBS, showing great symptom relief of bloating, gas, and pain (9), while some patients find relief by eliminating specific trigger foods like dairy or gluten.
  • Medications: Depending on whether you have IBS with constipation (IBS-C) or IBS with diarrhea (IBS-D), doctors may prescribe medications like laxatives, anti-diarrheal, or antispasmodics to manage symptoms.
  • Psychological approaches: Since stress and anxiety can exacerbate IBS, therapies like cognitive behavioral therapy (CBT) or gut-directed hypnotherapy (like Nerva) have shown promise in helping manage symptoms.
  • Probiotics: While probiotics can sometimes aggravate SIBO, they’re often beneficial for IBS patients in supporting healthy gut bacteria balance.

Why is IBS criticized as a label?

One of the biggest frustrations with an IBS diagnosis is that it can feel like a "wastebasket diagnosis"—a label given when doctors can't figure out exactly what's wrong.

In fact, some researchers believe that IBS is often misdiagnosed when in reality, patients may have an underlying condition like SIBO or even mild inflammatory bowel disease.

This misdiagnosis can lead to a frustrating cycle of trying different diets, medications, and supplements without ever addressing the root cause.

Conclusion on SIBO vs IBS

The road to understanding your gut health is rarely straightforward.

When it comes to SIBO vs IBS, knowing the key differences between these two conditions is essential in navigating your symptoms and finding a treatment plan that works.

While SIBO involves an overgrowth of bacteria that can be tested for and treated directly, IBS is a broader, more complex condition that often requires a multi-faceted approach, including diet, stress management, lifestyle changes, and sometimes medication.

If you’ve been diagnosed with IBS but feel like your treatment isn’t working, consider asking your doctor about SIBO testing.

Understanding the true source of your symptoms is the first step to reclaiming your gut health and your life.

This post is only for informational purposes and is not meant to diagnose, treat, or cure any disease. I recommend always consulting your healthcare practitioner before trying any treatment or dietary changes.

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10 alarming SIBO symptoms (and not just IBS)

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SIBO Symptoms

SIBO symptoms?

You cannot fit into your jeans anymore because you feel so bloated? You wake up with a flat belly in the morning, and in the evening, you look like six months pregnant? These may sound a bit extreme, but they are not exceptional cases. Many clients experience constant gas or bloating, and some of them already have the popular diagnosis of IBS.

I want to emphasize that bloating is not normal, especially when it happens constantly. It is always a sign of gut inflammation and irritation and is one of the leading SIBO symptoms.

What is SIBO?

SIBO stands for Small Intestinal Bacterial Overgrowth. It means an increase in the number of bacteria and/or changes in the types of bacteria present in the small intestine. SIBO symptoms and SIBO are commonly caused by an overgrowth of various bacteria that should generally be found in the large intestine. (1)

Classic SIBO symptoms are similar to IBS symptoms (Irritable Bowel Syndrome). These include abdominal pain, discomfort, cramping, gas, bloating, reflux, diarrhea, and/or constipation.

According to studies, 84 % of IBS cases are caused by SIBO. (2)

 

10 typical SIBO symptoms:

  1. You have constant bloating and gas – you may have difficulty figuring out which foods cause flatulence because you are bloated all the time, or bloating just increases as the day goes on.
  2. You have persistent diarrhea or constipation – hydrogen-dominant SIBO usually causes diarrhea, while "methane-dominant SIBO" (or precisely IMO- Intestinal Methanogen Overgrowth) mostly causes constipation, but this is also not always true! Mixed types are also common. (3)
  3. Your symptoms get worse when you eat fiber – You may have heard that the daily value for fiber is around 25 grams per day on a 2,000-calorie diet for adults (4). You still try to complete this challenge, but your symptoms have gotten worse. In that case, SIBO can be the culprit. Typically, a healthy gut needs fiber to feed the good bacteria and support normal function. However, your symptoms get worse if you feed the overpopulated bacteria. 
  4. You have several food intolerances, such as gluten, lactose, fructose, and histamine intolerance. – You lack enzymes, which are needed to break down certain foods, triggering a digestive response. (5)(6)
  5. You are already diagnosed with IBS – the majority of IBS patients have SIBO symptoms – you should not be satisfied with the IBS diagnosis; dig deeper!
  6. You feel worse after eating – You get full quickly after eating a normal-sized meal, which can happen when you have low stomach acid. (7) Slow stomach emptying when the food stays in your stomach for long hours, causing nausea, can contribute to SIBO. Damage to the migrating motor complex (MMC), which is usually responsible for sweeping food and bacteria through the digestive tract and gets activated when you don’t eat, is one of the most common underlying causes of SIBO. (8)
  7. You don’t do well with probiotics—do you get abdominal pain and cramping after eating fermented foods such as kefir, sauerkraut, and kimchi? Maybe you tried random multi-strain probiotics that just made everything worse. These could also be a sign of SIBO. 
  8. You have chronic illnesses such as chronic fatigue syndrome and autoimmune diseases - Leaky gut can also be a culprit if your gut remains “leaky,” and food particles, among others, can get into your bloodstream. These will activate your immune system, which will begin attacking foreign invaders, triggering inflammation. A long-term defense can lead to damage to your organs and food intolerances, as these foreign invaders may look similar to your own body’s cells, and the immune system gets confused, overloaded, and starts attacking your tissues. (9)
  9. You suffer from skin rashes and rosacea – an impaired gut (SIBO symptoms) can also cause skin problems.
  10. You have malabsorption issues, such as fat (which can also cause floating stools) and/or vitamin and mineral deficiencies, especially fat-soluble vitamins (D, E, K, A).

You can read more about SIBO symptoms and the SIBO testing options in my previous blog post.

 

This post is only for informational purposes and is not meant to diagnose, treat, or cure any disease. I recommend always consulting with your healthcare practitioner before trying any treatment or dietary changes.

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Consider SIBO testing if you suffer from constant bloating

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SIBO testing

What is SIBO & SIBO testing?

First of all, what is SIBO? SIBO stands for Small Intestinal Bacterial Overgrowth. It is defined as the presence of excessive bacteria in the small intestine. The problem is that there are too much bacteria and/or the wrong type of bacteria present in the wrong place.

Symptoms can be excess/trapped gas, bloating, diarrhea and/or constipation, abdominal pain or cramping, food sensitivities, chronic fatigue, brain fog, and the list goes on. (1)(2)

Before getting tested

Before getting to SIBO testing, many people try different methods to relieve their symptoms. These approaches may include lifestyle changes (e.g., reducing sugar/junk and processed food consumption; stress; getting more sleep) or eating more fiber, prebiotic foods, and herbs. However, if these changes don’t bring the expected results or make the current symptoms worsen, then it might be time to visit the GI doctor to have some tests.

Although having the symptoms mentioned above doesn’t mean that you have 100% SIBO. It is crucial to rule out other diseases (like endometriosis, Crohn’s/ Colitis) and get a proper diagnosis by your healthcare practitioner. There can be many different diseases, which could cause the same symptoms.

Suppose you have already been diagnosed with IBS (Irritable Bowel Syndrome). In that case, it is definitely worth getting SIBO testing because, according to a study, up to 84% of patients with IBS actually have SIBO. (3)

It may also happen that a person thought SIBO was causing the symptoms, but then the culprit turned out to be Celiac disease. (4) If you start using an antimicrobial treatment for assumed SIBO without any proper diagnoses, then it may cause more harm than good. So testing is essential, which can help define the treatment plan.

SIBO testing method #1: SIBO breath test

The three-hour lactulose or glucose breath test is generally used for diagnosing SIBO, which detects the different types of gases that bacteria produce in the small intestine. It checks for hydrogen and methane gas. (5) There is now a new test available in the US: the TrioSmart test that can detect the third type of gas: hydrogen sulfide. (6) I wrote about the different types of SIBO.

The bacteria in our intestines ferment specific carbohydrates, and they produce gases as a byproduct. The breath test involves drinking a sugar solution (lactulose or glucose, a type of carbohydrate) that feeds the bacteria in the gut, and they start making gases. Then these gases are absorbed in the intestines and get into our blood, from where the gases are delivered to our lungs and exhaled in our breath. That is what the breath test intended to capture.

The breath test is done for 3 hours, while breath samples are taken at 20-minute intervals. The first two hours represent the small intestine, and the last hour is usually the large intestine. Measuring the level of those gases is also important to determine how severe the bacterial overgrowth is and what treatment would suit the best.
Be aware that a prep diet is required to be followed before SIBO testing. It involves following a low-fiber diet and fasting for 14 hours. (When you order a test, you should receive instruction on the prep diet). (7)

A hydrogen breath test is also used for testing carbohydrate malabsorption issues when dietary sugars are not absorbed well, such as lactose (sugar in milk), fructose (sugar in fruit), sorbitol, and sucrose. (8)

 

Can you trust the SIBO breath tests?

While the breath test is considered the most practical SIBO testing method, it certainly has its limitations.
A meta-analysis of the breath test accuracy showed that lactulose substrate might provide a higher number of false-positive results than the glucose test. Glucose breath test seems to work better than lactulose breath test for diagnosing SIBO. It seems glucose testing has better sensitivity and specificity. (9) (10) In this case, clinicians may need to evaluate the results more carefully before giving out a diagnosis, and it would be worth doing a test for both types of substrates.

Other problems can be:
• the missing consensus on the interpretation of breath test results
• Individual’s motility can influence the test results – transit time may differ from person to person (11)

Other types of tests

If you have IBS-D or IBS-M/SIBO-D, you experience mainly diarrhea symptoms; then an IBS-SMART test is available to diagnose post-infectious IBS (PI-IBS). It is a blood test that looks for the markers of food poisoning (one of the leading causes of SIBO), which is the result of auto-antibodies forming in a lot of people and starting an auto-immune process. The antibodies measured in the blood are anti-CdtB toxin and anti-vinculin. These antibodies can attack the nerves of the gut and impair the cleaning wave, the Migrating Motor Complex. (12)(13)

What tests are not suitable to diagnose SIBO?

  • Stool tests because the results represent mainly the end of the large intestine, although they might indicate some issues in the small intestine but cannot diagnose SIBO. Overgrowth of bacteria in a stool can show dysbiosis.
  • Organic Acid Tests (OAT) check the urine for byproducts of yeast or bacteria in the small intestine, which can be very useful but cannot tell whether your SIBO is hydrogen/ hydrogen-sulfide or methane-dominant. (14)

Conclusions

Using SIBO testing (a breath test) has its advantages and disadvantages, but it can still be the most practical approach to diagnosing SIBO. Metanalysis showed that a glucose breath test might provide a more accurate diagnosis than a lactulose breath test. Having a SIBO diagnosis can be crucial as it can define the best treatment options (each type of gas requires different strategies).

Bear in mind that diagnosing SIBO might be just the first step because it will not tell you what caused SIBO in the first place. However, finding the underlying cause is crucial to prevent relapsing.

If you have questions regarding SIBO or need help finding out your root cause and support on your healing journey, then feel free to book a free consultation call!

 

 

* This post is only for informational purposes and not meant to diagnose or treat any disease.  I advise consulting with your healthcare practitioner regarding any treatment options or dietary changes.

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