Your IBS Is Probably SIBO
Irritable Bowel Syndrome is not a diagnosis. It is a description. It means your bowels are irritable and we do not know why. IBS is the label applied when a patient reports chronic bloating, abdominal pain, gas, and altered bowel habits, and standard evaluation including colonoscopy, celiac screening, and basic blood work reveals nothing explanatory. The label provides a billing code but no mechanism, no specific treatment target, and no resolution.
Research estimates that 60 to 78 percent of patients carrying an IBS diagnosis actually have SIBO, Small Intestinal Bacterial Overgrowth. This is not a theoretical overlap. It is a massive diagnostic failure affecting millions of patients who are being managed with fiber supplements, antispasmodics, and reassurance when they have a specific, testable, treatable condition with an identified mechanism.
The symptoms of SIBO mirror IBS precisely: bloating, often dramatic and worsening as the day progresses, abdominal distension, gas, abdominal pain, diarrhea or constipation or alternating between both, and post-meal discomfort. The similarity is not coincidental. In the majority of cases, they are the same condition. One has been given a mechanism and the other has been given a shrug.
At Kure Health, we do not diagnose IBS. We investigate what is causing the symptoms that other practices have labeled IBS. SIBO testing through lactulose breath test is a standard component of the GI evaluation within the VITAL Index for any patient presenting with chronic digestive complaints that have been attributed to IBS without further investigation.
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What SIBO Actually Is
The small intestine is designed to be relatively sterile compared to the colon. It is the primary site of nutrient absorption, and bacterial colonization in this region is normally prevented by gastric acid, bile production, immunoglobulin secretion, and the migrating motor complex, a cyclical wave of muscular contraction that sweeps bacteria and debris from the small intestine into the colon during fasting periods.
SIBO occurs when these protective mechanisms fail and colonic bacteria migrate into and proliferate in the small intestine. Once established, these bacteria ferment carbohydrates that are present in the small intestine during digestion, producing gases including hydrogen, methane, and hydrogen sulfide. The gas production causes the bloating, distension, and pain. The bacterial metabolic byproducts alter gut motility, damage the intestinal lining, and impair nutrient absorption.
The damage extends beyond digestive symptoms. SIBO-associated intestinal inflammation increases intestinal permeability, allowing bacterial endotoxins into the bloodstream and triggering systemic inflammation. Malabsorption of fat-soluble vitamins, iron, and B12 produces deficiency symptoms that seem unrelated to the gut: fatigue, brain fog, anemia, and neurological symptoms. The connection between gut overgrowth and systemic symptoms is often missed because the presentation crosses specialty boundaries.
SIBO is not rare. It is not a fringe diagnosis. It is an increasingly recognized condition with a clear mechanism, specific diagnostic testing, and established treatment protocols. The barrier to diagnosis is not scientific. It is a healthcare system that labels symptoms and stops investigating.
Why SIBO Keeps Coming Back
The recurrence rate for SIBO is frustratingly high, estimated at 40 to 50 percent within 12 months of successful antibiotic treatment. This recurrence is the most important clinical feature of the condition because it reveals that antibiotics alone are treating the overgrowth without addressing why the overgrowth developed. Killing the bacteria without fixing the conditions that allowed their proliferation guarantees their return.
The migrating motor complex is the most common underlying dysfunction. This interdigestive sweeping mechanism activates approximately every 90 minutes during fasting, clearing bacteria from the small intestine. Impairment of the MMC allows bacterial accumulation. MMC dysfunction can result from food poisoning through autoimmune damage to the vinculin protein (detectable via anti-vinculin antibody testing), diabetic gastroparesis, hypothyroidism, chronic opioid use, and chronic stress through vagal nerve suppression.
Structural causes include ileocecal valve dysfunction allowing retrograde bacterial migration from the colon, intestinal adhesions from surgery creating stagnant pockets where bacteria accumulate, and anatomical variations that impair normal flow. Low stomach acid from chronic PPI use, H. pylori infection, or aging reduces the gastric acid barrier that normally kills bacteria before they reach the small intestine.
Immune dysfunction plays a role in recurrence. Secretory IgA, the immunoglobulin that provides mucosal immune defense in the gut, may be depleted, reducing the immune surveillance that keeps small intestinal bacterial populations in check. Without identifying and addressing the specific underlying cause of bacterial overgrowth, each course of antibiotics provides temporary relief followed by predictable relapse.
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The Breath Test and What It Reveals
The lactulose breath test is the standard non-invasive diagnostic tool for SIBO. The patient ingests a lactulose solution after an overnight fast. Lactulose is a synthetic sugar that humans cannot digest or absorb. It passes through the small intestine intact until reaching bacteria, which ferment it and produce measurable gases. Breath samples collected at regular intervals over 2 to 3 hours measure hydrogen, methane, and in some tests hydrogen sulfide levels.
The timing and type of gas elevation determines the diagnosis. An early rise in hydrogen or methane, typically within the first 90 minutes, indicates small intestinal bacterial fermentation and confirms SIBO. Gas elevation only after 90 to 120 minutes typically reflects normal colonic fermentation. The distinction depends on the transit time of lactulose through the small intestine.
The gas type identifies the SIBO variant, which determines treatment. Hydrogen-dominant SIBO typically presents with diarrhea and responds to rifaximin, a non-absorbed antibiotic. Methane-dominant SIBO, technically intestinal methanogen overgrowth from archaea organisms rather than bacteria, presents with constipation and requires a combination of rifaximin and neomycin or allicin to target the methane-producing organisms. Hydrogen sulfide-dominant SIBO presents with mixed symptoms and foul-smelling gas and requires specific antimicrobial approaches.
At Kure Health, breath testing is paired with GI-MAP stool analysis for a complete gut evaluation. The breath test confirms SIBO and identifies the type. The GI-MAP identifies co-existing dysbiosis, pathogens, inflammatory markers, and permeability status that contribute to SIBO development and recurrence. Together, they provide the complete picture needed for root cause treatment.
Root Cause Treatment vs. Antibiotic Cycling
The conventional approach to SIBO is antibiotic treatment: rifaximin for hydrogen-dominant, rifaximin plus neomycin for methane-dominant, repeated as needed when symptoms recur. This approach reliably reduces bacterial overgrowth and provides symptomatic improvement for weeks to months. It does not prevent recurrence because it does not address why the overgrowth develops. The result is antibiotic cycling: treat, improve, relapse, repeat.
Root cause treatment requires identifying and addressing the specific mechanism allowing bacterial overgrowth. Anti-vinculin and anti-CdtB antibody testing identifies post-infectious autoimmune damage to the migrating motor complex, the most common underlying cause. When positive, prokinetic agents that stimulate the MMC are prescribed as ongoing maintenance to prevent bacterial reaccumulation after treatment.
Stomach acid assessment identifies whether hypochlorhydria from PPI use, H. pylori, or age-related decline is reducing the gastric barrier. Thyroid evaluation determines whether hypothyroidism is slowing gut motility. Ileocecal valve assessment identifies retrograde bacterial migration. Adhesion evaluation is considered in patients with surgical history. Each identified cause receives specific treatment rather than repeated antibiotic courses.
The Kure Health SIBO protocol sequences treatment in four phases. Phase one: antimicrobial treatment to reduce the current overgrowth using rifaximin, herbal antimicrobials, or both depending on the type and severity. Phase two: prokinetic therapy and underlying cause treatment to prevent recurrence. Phase three: gut restoration including mucosal repair, microbiome rebuilding, and nutrient repletion for deficiencies caused by malabsorption. Phase four: dietary optimization using a modified approach that reduces fermentable substrates during treatment and systematically reintroduces foods as the gut heals. Repeat breath testing at 8 to 12 weeks confirms eradication, and ongoing monitoring ensures the root cause treatment is preventing the relapse cycle.
