SIBO and IBS Testing: The Science Behind Trio-Smart and IBS-Smart
The gut-health world is crowded with products promising answers, but the evidence behind those promises varies widely. So when you come across an at-home test for small intestinal bacterial overgrowth (SIBO) or irritable bowel syndrome (IBS), it’s reasonable to ask where it was developed, how it’s validated, and what the results actually mean.
​
This article lays out the answers. It covers the research behind Gemelli Biotech's two main tests, the physicians involved in that research, the laboratory processes and standards each sample goes through, and what the evidence does and does not establish.
One thing worth saying up front: any diagnostic test is most useful in context and with appropriate medical guidance. Results should be interpreted by a qualified healthcare professional who can weigh them against your history, your symptoms, and the rest of your clinical picture [25].
Table of Contents
-
Built on Research From Cedars-Sinai
-
Breath Testing Is an Established Part of GI Medicine
-
Why Measuring Three Gases Matters
-
​The Evidence Behind Trio-Smart
-
​​IBS-Smart and Post-Infectious IBS
-
Laboratory Standards and Physician Oversight
-
​Better Answers Can Mean Fewer Diagnostic Detours
-
The Bottom Line
-
Frequently Asked Questions
Built on Research From Cedars-Sinai
The science behind Gemelli's tests grew out of decades of work at the Medically Associated Science and Technology (MAST) Program at Cedars-Sinai in Los Angeles. Gemelli, based in Mesa, Arizona works in partnership with MAST and licenses diagnostic technology from Cedars-Sinai [1, 26, 28, 30].
MAST is directed by Dr. Mark Pimentel, whose research has shaped much of how gastroenterologists think about these conditions. His early work connected IBS to bacterial overgrowth in the small intestine and led to a randomized trial showing that the antibiotic rifaximin improved symptoms [32, 17]. Later research established that methane slows the passage of food through the intestine [18], and identified a specific organism, Methanobrevibacter smithii, as the primary methanogen in patients with constipation-predominant IBS and methane on breath testing [19]. More recently, his team identified and validated the antibody biomarkers that IBS-Smart measures today [10, 11].
Much of that research has been aimed at addressing a familiar clinical problem. Patients with these symptoms often spend years cycling through appointments and procedures without a clear answer, and the disappointment and cost add up along the way.
"Many patients could avoid years of frustration and hefty medical costs with one timely breath test," Dr. Pimentel has said [30].
​
That work continues at Cedars-Sinai, and experts in the field are building on its foundation and pushing the boundaries of medicine forward. Gemelli Biotech maintains a Scientific Advisory Board (SAB) that includes gastroenterologists and motility specialists at academic medical centers across the United States, Canada, and Mexico [30].
Current board members include Dr. Darren Brenner of Northwestern University's Feinberg School of Medicine and Dr. Linda Nguyen of Stanford University School of Medicine, both co-authors of a recent study of three-gas breath testing in everyday clinical practice. That study, covering more than 3,000 patients across 49 states, was published in the Journal of Clinical Gastroenterology in 2026 and is discussed more below [1]. Other board members helped write the standards the field runs on, including the Rome criteria used to diagnose IBS worldwide and the North American Consensus that governs how breath tests are performed and read [3, 30].​​
Breath Testing Is an Established Part of GI Medicine
Breath testing is not a novelty. Clinicians have used hydrogen breath testing in gastrointestinal medicine since the 1970s, and it has become a widely used tool for assessing SIBO [1].
​
The logic behind it is straightforward. A breath test starts with a measured dose of sugar, either lactulose or glucose, which gives the microbes in the gut something to ferment. Human cells do not produce hydrogen, so any hydrogen that shows up in the breath afterward came from that fermentation [1]. Some of that gas crosses into the bloodstream and is exhaled, which makes a breath sample a usable window into fermentation happening in the intestine [1, 3]. By the early 1990s, breath testing had expanded beyond hydrogen to include methane, a gas produced by methanogenic archaea in the gut rather than by bacteria [1]. Its clinical significance became clear over the following years: methane is associated with a constipation phenotype, and it slows intestinal transit rather than sitting inert in the gut [1, 18].
​​​​How Breath Testing Became Standardized
After these mechanisms were established, professional standards followed. The 2017 North American Consensus, published in the American Journal of Gastroenterology, standardized substrate doses and result interpretation: a hydrogen rise of at least 20 parts per million (ppm) above baseline within 90 minutes is a positive result for SIBO, and methane at 10 ppm or more is a methane-positive result [3]. In 2020, the American College of Gastroenterology published its SIBO guideline, which established the definitions of SIBO and intestinal methanogen overgrowth (IMO) [4]. European gastroenterology, endoscopy, and pediatric societies also issued their own joint guideline on hydrogen and methane breath testing in 2022 [6].
​
Trio-Smart follows those standards, reporting hydrogen and methane results against the thresholds the Consensus established [1].
​
None of this means breath testing is finished science. Laboratory and clinical studies are being conducted all the time, and researchers are still testing and refining thresholds [1]. Science doesn’t rest once discoveries are made, and dedicated scientists continue to challenge and advance the field in the hopes of expanding our knowledge of microbial overgrowths and how they affect the human body.​
​Why Measuring Three Gases Matters
Gut microbes produce more than one gas, and sometimes one becomes fuel for the next. Methane-producing archaea and sulfate-reducing bacteria both consume hydrogen to make methane and hydrogen sulfide, respectively, which means hydrogen readings can drop even when fermentation is very active [23]. A low hydrogen result, in other words, does not always mean little is happening. Measuring all three gases helps reduce the chance of misinterpreting your results due to an incomplete picture.
Each gas carries different clinical information. Hydrogen supports a SIBO diagnosis. Methane is associated with constipation and defines IMO. Hydrogen sulfide is associated with diarrhea, urgency, and abdominal pain, and is used to identify intestinal sulfide overproduction (ISO).
Hydrogen sulfide went unmeasured for years for two practical reasons. Conventional breath testing instruments were designed to detect hydrogen and methane, and had no capacity to measure a third gas. Hydrogen sulfide is also chemically reactive, which means it can be lost or altered during storage unless the sample is contained in a way that preserves it in transit to the laboratory [1, 27].
Trio-Smart addresses both constraints. Samples are collected in a specialized foil bag that retains hydrogen, methane, and hydrogen sulfide for 7 to 10 days, long enough to cover shipment back to the lab. And the samples are analyzed on a special gas chromatography instrument designed to measure all three gases together. These technological advancements are why Trio-Smart is currently the only clinical breath test that measures all three gases [26, 30].​
​
Two-Gas vs Three-Gas Breath Testing
Hydrogen sulfide was invisible to breath testing before Trio-Smart. Switch the view below to see the same patient’s samples read by a conventional two-gas test, then by Trio-Smart.
​The Evidence Behind Trio-Smart
Two main questions matter for any laboratory test: does it measure what it claims to measure, and do those measurements mean anything for patients?
Before Trio-Smart reached patients, its four-gas analyzer (measuring the three gut gases discussed above, plus carbon dioxide, which is used to standardize each sample) was tested against conventional breath testing equipment. Trio-Smart matched its performance, with the added ability to measure hydrogen sulfide accurately within its detection range [1, 22]. It has a reported detection sensitivity of ±0.1 ppm, compared with ±2 ppm for conventional breath-testing equipment, making it 20 times more sensitive. This matters because hydrogen sulfide appears in breath at far lower concentrations than hydrogen or methane.
​
Do Breath Gases Reflect What’s Happening in the Gut?
A breath test is an indirect measurement, so the logical next question is whether the gases in a patient's breath actually reflect what the microbes in their gut are producing. Three studies have taken up that question, each one looking closer than the last.
The first, published in the American Journal of Gastroenterology in 2022, compared breath results with stool samples. Patients with high breath methane had more methane-producing microbes in their stool, and the same held for hydrogen sulfide. Those patterns also helped distinguish IBS with constipation from IBS with diarrhea [7]. A 2025 study found the same correlations using samples taken from the small intestine rather than stool [8]. A third study, presented at Digestive Disease Week 2026, went further still: researchers collected breath samples and gas drawn directly from the duodenum in the same 52 patients on the same day. The methane and hydrogen sulfide readings on the breath test correlated with the concentrations measured inside the small intestine, and higher hydrogen sulfide meant more severe diarrhea whether it was measured in the breath or in the gut [24].
That last result addresses the most common objection to breath testing. Because the sugar substrate eventually reaches the colon, critics have argued that a breath test may simply be picking up ordinary colonic fermentation instead of anything happening in the small bowel. But when researchers sampled both at once, the gases in the breath tracked the gases in the small intestine [6, 8, 24].
​
How Trio-Smart Performs in the Real World
What remained was to see whether this holds up outside a research setting. In 2026, the Journal of Clinical Gastroenterology published a nationwide study of Trio-Smart in ordinary clinical practice. Tests went out by mail to 6,000 patients, ordered by 1,548 different providers across 49 states, and 3,563 came back. After the questionnaires were screened and the breath tests passed quality checks, 3,004 patients made up the final study group [1].
​
The same relationships held. Methane tracked with more severe constipation. Hydrogen sulfide tracked with more severe diarrhea, urgency, and abdominal pain. A machine learning analysis of the full symptom data found hydrogen sulfide driving overall symptom severity, and patients with ISO reported the highest pain and severity scores of any group. The authors concluded that at-home three-gas breath testing "is of high quality" and that the gases it detects have significant relationships to patients' symptoms [1].
They were equally direct about what the study could not establish. There was no healthy control group, so the positivity rates should not be read as prevalence figures for the general population, and symptoms were patient-reported rather than clinically assessed [1].​
​​IBS-Smart and Post-Infectious IBS
Gas measurements describe what is happening in the gut today. They don’t necessarily explain how it started. For many patients with IBS, the origin is an infection they may barely remember, and finding that evidence means looking in the blood rather than the breath.
Food poisoning can leave lasting damage. A meta-analysis of 45 studies covering 21,421 people found that 10.1% had IBS a year after an episode of infectious enteritis, and 14.5% did at longer follow-up, a risk more than four times higher than in people who had not been infected [12]. The pattern is well enough established to have its own Rome Foundation working team report, which is how the field formally recognizes a condition and sets guidance for diagnosing and treating it [13].
​
How an Infection Can Lead to IBS
Research has traced a pathway from foodborne illness to IBS, and the mechanism is well described. Some of the bacteria behind food poisoning, Campylobacter among them, release a toxin called cytolethal distending toxin B, or CdtB. The immune system does what it should and builds antibodies to fight the toxin.
​
The catch is that CdtB closely resembles vinculin, a protein the body's own cells use to hold their structure, including cells that help move food through the intestine. Antibodies aimed at the toxin can begin attacking vinculin instead, and that misdirected response is thought to interfere with normal gut movement long after the infection itself is gone [11]. Laboratory research provides further evidence of this pathway: animals exposed to the toxin develop these antibodies and the gut changes that follow, while animals exposed to a version of the bacteria without CdtB largely do not [11].
​
What IBS-Smart Measures
IBS-Smart looks for both of those antibodies in a blood sample the patient collects at home [30]. In the validation study of the current test, anti-CdtB was 93.5% specific and anti-vinculin 90.9% specific when separating IBS with diarrhea from inflammatory bowel disease. That is what makes a positive result so meaningful. For a patient whose symptoms already point toward IBS with diarrhea, the researchers calculated that having both antibodies elevated raised the estimated post-test probability of IBS-D above 98% [10].
A negative result carries less weight, and it is worth being clear about why. IBS-Smart is designed to detect post-infectious IBS, and IBS has other possible causes, so a negative result does not rule out IBS from a different origin. This is why a negative result is a useful piece of information rather than a conclusion and should be discussed with your healthcare team in the context of your specific history and symptoms.
Newer work continues to tie these antibodies to measurable changes in the gut. In 614 patients who underwent upper endoscopy, those with elevated anti-CdtB were significantly more likely to have SIBO confirmed by culture, and those with elevated anti-vinculin had less microbial diversity and far higher levels of the two bacteria most associated with SIBO, a profile that tracked with more severe diarrhea and urgency [24].
All of this fits where mainstream practice has been heading. The ACG's 2021 IBS guideline does not recommend IBS-Smart specifically, but it does call for a positive diagnostic strategy, meaning clinicians should work toward confirming IBS rather than relying on a long process of exclusion [5]. Biomarker testing gives them one more piece of objective evidence to weigh.​​
​Laboratory Standards and Physician Oversight
Every Trio-Smart and IBS-Smart sample is analyzed in a CLIA-certified laboratory [27, 30]. CLIA refers to the Clinical Laboratory Improvement Amendments, the federal standards that govern laboratories testing human specimens in the United States. CLIA establishes federal requirements covering laboratory quality systems, personnel qualifications, quality control, and, where applicable, proficiency testing and inspection [29].
Three practices matter most in the handling of a mailed breath sample, and Trio-Smart's laboratory follows all three. Samples that fail quality checks are set aside rather than reported, so a patient does not receive a number the laboratory cannot stand behind. Carbon dioxide is measured in every sample so the lab can account for differences in how concentrated each breath sample is. That lets the three gas readings be adjusted to a consistent standard, making results more comparable even if one breath sample is more diluted than another. And the collection bags are built to hold all three gases for 7 to 10 days, the window a mailed sample needs to survive, which is what allows a reactive gas like hydrogen sulfide to be measured accurately after transit [1].
​
Clinical Lab Testing vs. Consumer Breath Trackers
These checks and standards exist to make the process consistent and reliable, and they are the clearest difference between laboratory breath testing and reusable consumer breath trackers. The two are not really the same category of product. Trio-Smart samples are analyzed by trained technicians on laboratory instruments that operate inside a monitored quality-control system, with daily calibration and verification. Equipment that falls outside specification is taken out of service until it has been tested, recalibrated, and cleared for use.
​
A consumer device works differently. Its accuracy depends on a sensor that stays in the user’s home, without the same routine laboratory quality-control checks against known standards. If that sensor drifts or is damaged, it may still produce a plausible-looking reading, and the user may not realize that its accuracy has changed.
​
Physician Oversight & Guidance
Both Trio-Smart and IBS-Smart are physician-authorized. Your healthcare provider can order them for you, much like a blood test or a colonoscopy. Or you can order directly through Gemelli's website, in which case your request goes to a licensed physician who reviews it before the kit is sent. No test is processed without a clinician signing off. The difference between the two routes is convenience, not oversight. Either way, results are meant to be read by a healthcare professional who knows your history [25, 30].
​
For a long time, conditions like IBS were treated as diagnoses of exclusion, assigned only after other explanations had been eliminated. As our understanding of gut health has evolved, that has been changing. Microbial overgrowth is now recognized as a measurable contributor to chronic gut symptoms and is addressed in ACG guidelines, while the ACG's IBS guideline recommends a positive diagnostic strategy rather than relying solely on a process of exclusion [4, 5]. That means these symptoms can increasingly be investigated directly rather than only by ruling everything else out.
​
Gemelli reports that more than 200,000 patients and physicians have turned to Trio-Smart and IBS-Smart for actionable data to work from and real answers [30]. But an answer is only worth as much as the process that produced it. So, when you weigh your next steps and decide which test is right for you, look for one whose process has been validated and documented at every step.
​Better Answers Can Mean Fewer Diagnostic Detours
Anyone who has lived with chronic gut symptoms knows the pattern: appointments, referrals, procedures, and stretches of waiting in between, often without arriving anywhere definite. In a survey of nearly 2,000 IBS patients, the average person reported being diagnosed 6.6 years after their symptoms started [31]. That path is hard on patients, and it is expensive.
​
The search for answers can be expensive. In a large U.S. claims analysis, adults with IBS and diarrhea averaged just over $13,000 a year in total healthcare spending, with more than half going to office visits and outpatient services, including diagnostic testing and imaging [15]. Other analyses have found that IBS adds roughly $2,300 to $3,900 per patient per year in healthcare costs compared with similar people without IBS, even after accounting for age, sex, and other health conditions [15, 16]. Those studies relied on earlier claims data, so the figures should not be read as current 2026 estimates. If anything, today’s nominal costs may be higher, making the studies a useful illustration of just how substantial the financial burden of repeated evaluation and ongoing care can become.
​
Using Test Results to Guide Treatment
Testing may help streamline that search in two ways. The first is by guiding treatment. Among 93 patients with IBS and diarrhea treated with rifaximin, an antibiotic the ACG recommends for this patient population, 59.7% of those with a positive breath test improved, compared with 25.8% of those whose test was negative [5, 14]. In other words, the test result predicted who the drug would help. Earlier research found the same principle at work in constipation, where the presence of methane helped predict which antibiotic approach worked best [20, 21].
​
The second is by shortening the path itself, by using earlier testing to reduce potentially unnecessary and costly procedures. A 2026 study in Frontiers in Gastroenterology reviewed the records of 219 adults evaluated for IBS symptoms at two U.S. gastroenterology practices. Among patients who received neither test, 60.7% went on to have a colonoscopy. Among those who received both IBS-Smart and Trio-Smart, 27.3% did. Costs followed the same pattern, averaging roughly $360 to $385 per patient per month in the tested groups against $960 in the untested group [2, 25]. Because the study was observational, the findings show an association rather than proving that the testing itself caused the lower utilization and costs.
​
"What we saw is that selected use of noninvasive testing may help clinicians organize the diagnostic process more efficiently," said Dr. Leonard Weinstock, the study's lead author and a gastroenterologist with Gastrointestinal Alliance. "That does not mean these tests replace careful clinical evaluation, a Rome IV-based diagnosis, or appropriate rule-out testing." [25]
​
In other words, testing works best as part of a clinical evaluation, not a substitute for one. But when used appropriately and in the right context, it can get doctors and patients to better answers, faster.​
The Bottom Line
Trio-Smart and IBS-Smart are built on published science and years of clinical use. Their foundation includes decades of gastroenterology research, peer-reviewed microbiome and biomarker studies, professional standards for how breath testing should be performed and read, clinical laboratory infrastructure, and a growing body of real-world evidence. Trio-Smart extends conventional breath testing by measuring hydrogen, methane, and hydrogen sulfide together, and IBS-Smart gives clinicians a way to detect antibodies associated with post-infectious IBS.​
Neither test answers every question about gut symptoms. But both offer something that can be hard to come by during a long diagnostic search: objective biological information that helps determine what to do next.​
To learn more, visit triosmartbreath.com or ibssmart.com. Patients can find articles and resources to help answer any questions they might have, as well as a link to order either test. Clinicians can find ordering and interpretation information on the prescriber pages of each site.
Frequently Asked Questions
How accurate is the Trio-Smart breath test?
Trio-Smart is a clinically validated breath test designed to measure hydrogen, methane, and hydrogen sulfide. Its laboratory technology has been tested against established breath-testing equipment, and published research has shown that the gases it measures correspond with both the microbes found in the gut and the symptoms those gases are known to cause. In a nationwide study of more than 3,000 patients, methane tracked with constipation, while hydrogen sulfide tracked with diarrhea, urgency, and abdominal pain. Every sample is analyzed in a CLIA-certified laboratory using established breath-testing standards [1, 3, 7, 8, 22, 24, 27].
​
What is the difference between Trio-Smart and a standard SIBO breath test?
Most SIBO breath tests measure hydrogen and methane. Trio-Smart measures both of those gases plus hydrogen sulfide, giving patients and clinicians a more complete picture of microbial gas production in the gut. That matters because hydrogen-sulfide-producing microbes consume hydrogen, which can sometimes make a two-gas breath test appear normal even when significant microbial activity is present [1, 26, 30].
​
Can I take a SIBO breath test at home?
Yes. Trio-Smart is collected at home and then mailed to the laboratory for analysis. Its specialized collection bags are designed to preserve hydrogen, methane, and hydrogen sulfide for 7 to 10 days, allowing even reactive hydrogen sulfide to remain measurable after shipping [1].
​
What is hydrogen sulfide SIBO, or ISO?
“Hydrogen sulfide SIBO” is a term people sometimes use for intestinal sulfide overproduction (ISO), a condition associated with excess hydrogen sulfide production in the gut. Research has linked elevated hydrogen sulfide with diarrhea, urgency, abdominal pain, and greater overall symptom severity. Because traditional breath tests do not measure hydrogen sulfide, this pattern could previously go undetected [1].
​
What is the difference between Trio-Smart and IBS-Smart?
Trio-Smart and IBS-Smart look for different biological clues. Trio-Smart is a breath test that measures hydrogen, methane, and hydrogen sulfide produced by gut microbes, while IBS-Smart is a blood test that measures antibodies associated with the post-infectious pathway to IBS. Depending on your symptoms and history, a clinician may recommend one test or both.
​
How accurate is the IBS-Smart blood test?
IBS-Smart measures two antibodies associated with post-infectious IBS: anti-CdtB and anti-vinculin. In its validation study, anti-CdtB was 93.5% specific and anti-vinculin was 90.9% specific for distinguishing IBS with diarrhea from active inflammatory bowel disease. Among patients whose symptoms already made IBS-D likely, testing positive for both antibodies raised the estimated probability of IBS-D above 98%. A negative result is less conclusive, however, because the test is not designed to identify every possible cause of IBS and does not rule IBS out [10].
​
Do I need a doctor to order Trio-Smart or IBS-Smart?
Your healthcare provider can order either test, or you can begin the process through Gemelli’s online patient platform, where a provider reviews and authorizes the order. Results are intended to be interpreted with a healthcare professional who can consider them alongside your symptoms, medical history, and other testing.
​
Are Trio-Smart and IBS-Smart processed in a CLIA-certified laboratory?
Yes. Trio-Smart and IBS-Smart samples are analyzed in a CLIA-certified clinical laboratory. CLIA—the Clinical Laboratory Improvement Amendments—is the federal framework that sets quality standards for laboratories testing human specimens, including requirements related to personnel, quality control, laboratory procedures, and, where applicable, proficiency testing and inspection. CLIA certification applies to the laboratory performing the testing and helps ensure that patient samples are handled and analyzed under established clinical laboratory standards [27, 29, 30].
​
Where does the research behind Trio-Smart and IBS-Smart come from?
Much of the foundational research behind Trio-Smart and IBS-Smart comes from the MAST Program at Cedars-Sinai, with additional research involving investigators at other academic medical centers. Some studies have received funding from Gemelli Biotech, and some researchers or advisors have financial relationships with the company; those relationships are disclosed in the published literature. The broader evidence base also includes independent clinical guidelines, epidemiologic research, and microbiome studies from institutions outside Gemelli [1, 3, 6-10, 12, 13, 24].
References
-
Digestive Disease Week (DDW) 2026 abstracts: Villanueva-Millan MJ, et al. Breath H2S and CH4 Correlate With the Same Gases in the Duodenum and Gastrointestinal Symptoms. Poster #1699. Gastroenterology. 2026;170(6):S-1961. DOI: 10.1016/S0016-5085(26)04698-6; Leite G, et al. Higher Levels of Serum Anti-Vinculin Antibodies Correlate With Greater Severity of Gastrointestinal Symptoms and Small Intestinal Bacterial Overgrowth (SIBO) Microbial Profile Based on Quantitative Shotgun Sequencing. Poster #767. Gastroenterology. 2026;170(6):S-1795. DOI: 10.1016/S0016-5085(26)04342-8; Leite G, et al. Levels of Serum Antibodies to Cytolethal Distending Toxin B (CdtB) in Human Subjects Predict SIBO by Small Bowel Culture and an Altered Small Intestinal Microbiome by Shotgun Sequencing. Poster #1266. Gastroenterology. 2026;170(6):S-2487. DOI: 10.1016/S0016-5085(26)05889-0; Brimberry D, et al. Foreign Travel Is Associated With Changes in the Small Bowel Microbiome and With Elevations in Anti-Vinculin Antibody Levels. Poster #1263. Gastroenterology. 2026;170(6):S-2485-S-2486. DOI: 10.1016/S0016-5085(26)05886-5. See also Gemelli Biotech’s DDW 2026 research overview.
-
CMS: Clinical Laboratory Improvement Amendments (CLIA). CDC: About CLIA.
-
Gemelli Biotech sites: gemellibiotech.com, Scientific Advisory Board, triosmartbreath.com, ibssmart.com.
-
Drossman DA, Morris CB, Schneck S, et al. International survey of patients with IBS: symptom features and their severity, health status, treatments, and risk taking to achieve clinical benefit. J Clin Gastroenterol. 2009;43(6):541-550. https://pmc.ncbi.nlm.nih.gov/articles/PMC2700202/
-
Pimentel M, Chow EJ, Lin HC. Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome. Am J Gastroenterol. 2000;95(12):3503-3506. doi:10.1111/j.1572-0241.2000.03368.x. https://pubmed.ncbi.nlm.nih.gov/11151884/