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Understanding IBS: A Comprehensive Guide to Diagnosis, Causes, and Gut-Focused Solutions

  • liasonnenburg
  • May 4
  • 4 min read

Updated: May 14


Irritable Bowel Syndrome (IBS) is a chronic functional disorder of the gastrointestinal tract that affects an estimated 5–15% of the global population [3, 4]. Characterized by abdominal pain, bloating, and changes in bowel habits—including constipation, diarrhea, or both—it can significantly disrupt daily life [1, 2].


Although common, IBS remains poorly understood, and currently, no definitive diagnostic test or biomarker exists. Instead, diagnosis is based on Rome IV clinical criteria, which requires symptom onset at least six months prior, ongoing symptoms for the last three months, and abdominal pain at least once a week associated with defecation, a change in stool form, or stool frequency [6, 7].

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What Causes IBS?

IBS is considered a multifactorial condition, meaning several overlapping causes may be at play, including:

  • Dysregulation of the gut-brain axis [5, 6]

  • Psychosocial stressors such as anxiety or trauma [5]

  • Altered motility or sensation of the intestines

  • Food sensitivities, especially to fermentable carbohydrates known as FODMAPs [6]

  • Gut dysbiosis, or an imbalance in the gut microbiome [12]


The Role of Dysbiosis

In the early 2000s, researchers began noticing that people who experienced gastrointestinal infections were more likely to develop IBS afterward. This post-infectious IBS appears to stem from lasting changes in the gut microbiota—the trillions of bacteria and other microbes in our digestive tract [12].


Those who developed IBS after an infection were found to have a different microbiome makeup than those who recovered fully. This led to the hypothesis that microbial imbalance, or dysbiosis, disrupts immune regulation in the gut, leading to chronic inflammation and symptoms [12].

There are roughly 100 trillion microbes in the gut—outnumbering human cells by a factor of 10 [13]. These microbes help digest food, produce nutrients, regulate the immune system [14], and even influence mood, cognition, and behavior [15].


While small imbalances may cause minor digestive upset, significant dysbiosis can contribute to chronic conditions like IBS. What's challenging is that there’s no single dysbiosis pattern in IBS; every individual presents with a unique microbial imbalance [12].


IBS and Coexisting Conditions

IBS is not an isolated disorder. Up to two-thirds of IBS patients also experience functional dyspepsia, presenting with upper abdominal discomfort, bloating, nausea, or early fullness after eating [9]. Additionally, about half of IBS sufferers also meet criteria for other chronic pain or functional disorders, including:

  • Fibromyalgia

  • Chronic fatigue syndrome

  • Chronic pelvic or back pain

  • Temporomandibular joint (TMJ) dysfunction [10]


These comorbidities highlight the systemic nature of IBS and the need for a holistic, multi-layered approach to care.


Diagnostic Testing: Beyond Symptom Checklists

Since IBS lacks a definitive test, diagnosis is often one of exclusion. Clinicians frequently order:

  • Celiac screening (tTG, EMA, DGP antibodies)

  • Stool calprotectin to rule out inflammatory bowel disease (IBD)

  • Breath tests for Small Intestinal Bacterial Overgrowth (SIBO), which may underlie up to 78% of IBS cases [6]

  • GI-MAP (PCR stool testing), which assesses gut pathogens (e.g., H. pylori), microbial diversity, inflammation markers, and digestive function

These modern tools help uncover hidden causes and target treatment more effectively.


Case Study: From Post-Infectious IBS to Resilience

A 39-year-old woman presented with frequent bowel movements, urgency, bloating, and mucus in her stool. Her symptoms began after a trip to the Azores in 2022 where she developed acute gastrointestinal symptoms. Though these initially resolved, she soon experienced recurrent digestive issues.


She was diagnosed with IBS after tests ruled out structural issues, but symptoms persisted. A GI-MAP test revealed:

  • Pathogens: Helicobacter pylori, Entamoeba coli

  • Dysbiosis: Low keystone species, overgrowth of opportunistic bacteria

  • Digestive insufficiency: Low elastase-1, steatocrit, and high β-glucuronidase

Treatment included herbal antimicrobials, targeted probiotics, and digestive enzymes. Within weeks, bloating and gas resolved, bowel movements normalized, and she reported a significant improvement in well-being and resilience.


Holistic and Microbiome-Focused Treatment

Because IBS is so individualized, treatment should be personalized and comprehensive. Key components may include:


  • Low-FODMAP or anti-inflammatory diets

  • Eradication of pathogens or bacterial overgrowth

  • Microbiome restoration with tailored probiotics and prebiotics [17]

  • Digestive enzyme support

  • Stress regulation via mindfulness, therapy, or vagus nerve stimulation


Microbiome testing, such as the GI-MAP offers actionable insights, identifying imbalances, inflammation, and enzyme deficiencies, allowing targeted intervention rather than generic symptom management.


Final Thoughts

IBS is not simply a nuisance—it’s a sign of deeper dysregulation in the digestive and immune systems. A diagnosis of IBS doesn’t have to mean a lifetime of suffering. With the right testing, insights, and personalized support, patients can rebuild digestive health from the ground up.

At our clinic, we specialize in supporting gut health through advanced diagnostics and microbiome-focused treatment strategies. If you’re struggling with unresolved digestive symptoms, it might be time to explore a deeper, more integrative approach.


References

  1. Lacy BE, et al. Gastroenterology. 2016;150:1393–1407.e5. doi:10.1053/j.gastro.2016.02.031

  2. Drossman DA, Hasler WL. Gastroenterology. 2016;150:1257–1261. doi:10.1053/j.gastro.2016.03.035

  3. Sperber AD, et al. Gut. 2017;66:1075–1082. doi:10.1136/gutjnl-2015-311240

  4. Black CJ, Ford AC. Nat Rev Gastroenterol Hepatol. 2020;17:473–486. doi:10.1038/s41575-020-0286-8

  5. Patel N, Shackelford KB. StatPearls [Internet]. 2025.

  6. Weaver KR, Melkus GD, Henderson WA. Am J Nurs. 2017;117(6):48-55. doi:10.1097/01.NAJ.0000520253.57459.01

  7. Rome IV Criteria. AJN. 2017;117(6):48-55.

  8. Agreus L, et al. Gastroenterology. 1995;109(3):671–680. doi:10.1016/0016-5085(95)90373-9

  9. Talley NJ, et al. Am J Gastroenterol. 2003;98(11):2454–2459. doi:10.1016/S0002-9270(03)00705-6

  10. Napolitano M, et al. Microorganisms. 2023;11(10):2369. doi:10.3390/microorganisms11102369

  11. Canavan C, et al. Clin Epidemiol. 2014;6:71–80. doi:10.2147/CLEP.S40245

  12. Campbell K. Canadian Digestive Health Foundation, 2024.

  13. Ferranti E, et al. J Cardiovasc Nurs. 2014;29(6):479–481. doi:10.1097/JCN.0000000000000166

  14. Wiertsema SP, et al. Nutrients. 2021;13(3):886. doi:10.3390/nu13030886

  15. Sherwin E, et al. Curr Opin Gastroenterol. 2016;32(2):96–102. doi:10.1097/MOG.0000000000000244

  16. Hrncir T. Microorganisms. 2022;10(3):578. doi:10.3390/microorganisms10030578

  17. Hrncir T. Ibid.


 
 
 

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