← Back to Home

Irritable Bowel Syndrome (IBS)

Description

Irritable Bowel Syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by abdominal pain, bloating, and altered bowel habits (diarrhea, constipation, or both). Unlike inflammatory bowel disease, IBS does not cause visible intestinal damage, but it severely impacts quality of life through persistent digestive discomfort.

IBS is driven by gut-brain axis dysfunction, visceral hypersensitivity, dysbiosis, and low-grade inflammation. The gut becomes overly reactive to stress, food triggers, and microbial imbalances, leading to abnormal motility (too fast or too slow), increased pain signaling, and excessive gas production.

  • Dysbiosis: Imbalanced gut microbiota produce excess gas, trigger inflammation, and impair nutrient absorption.
  • FODMAP sensitivity: Fermentable carbohydrates (FODMAPs) are poorly absorbed and rapidly fermented by gut bacteria, causing bloating, cramping, and diarrhea.
  • Gut-brain axis: Chronic stress and anxiety amplify gut symptoms through vagal nerve signaling and cortisol dysregulation.
  • Leaky gut: Increased intestinal permeability allows bacterial endotoxins to trigger systemic inflammation.

Dietary interventions are the most effective treatment for IBS. A low-FODMAP diet dramatically reduces symptoms by eliminating fermentable carbohydrates that feed problematic bacteria. Carnivore or ketogenic diets further calm IBS by removing all plant fibers and carbohydrates, starving out gas-producing bacteria and reducing gut inflammation. Many people achieve complete remission on these diets.

IBS symptoms worsen with high-carbohydrate, high-fiber, and processed foods, while improving with elimination diets, stress management, and microbiome rebalancing.

Root Causes

FODMAP Consumption
[ 1 ] Emma P Halmos et al. (2013) DOI PMID [ 2 ] H M Staudacher et al. (2011) DOI PMID [ 2 ] H M Staudacher et al. (2011) DOI PMID [ 3 ] Joost P Algera et al. (2022) DOI PMID [ 4 ] Christopher J Black et al. (2021) DOI PMID [ 5 ] Heidi M Staudacher et al. (2020) DOI PMID [ 6 ] Sanna Nybacka et al. (2024) DOI PMID
Carbohydrate consumption
[ 7 ] Gregory L Austin et al. (2009) DOI PMCID PMID [ 6 ] Sanna Nybacka et al. (2024) DOI PMID
Fiber Consumption
[ 8 ] C Y Francis et al. (1994) DOI PMID [ 9 ] Paul Moayyedi et al. (2014) DOI PMID
HPA Axis Dysregulation
[ 10 ] Fatima Soufan et al. (2025) DOI PMCID PMID
Gut Dysbiosis
[ 11 ] Lin Wang, Nuha Alammar et al. (2020) DOI PMID
Leaky Gut (Intestinal Permeability)
[ 12 ] Nikita Hanning et al. (2021) DOI PMCID PMID [ 13 ] Simon P Dunlop et al. (2006) DOI PMID

Treatment Options

Carnivore Diet
Ketogenic Diet
[ 14 ] Qi Yan Ang et al. (2020) DOI PMCID PMID [ 15 ] Leslyn Rew et al. (2022) DOI PMCID PMID [ 16 ] Andrea Santangelo et al. (2023) DOI PMCID PMID
Fasting
[ 17 ] Xiangwei Hu et al. (2023) DOI PMCID PMID [ 18 ] Valter D Longo et al. (2016) DOI PMCID PMID

Sources

[1] A diet low in FODMAPs reduces symptoms of irritable bowel syndrome
[ 1 ] Emma P Halmos et al. (2013) DOI PMID
[2] Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome
[ 2 ] H M Staudacher et al. (2011) DOI PMID
[3] Low FODMAP diet reduces gastrointestinal symptoms in irritable bowel syndrome and clinical response could be predicted by symptom severity: A randomized crossover trial
[ 3 ] Joost P Algera et al. (2022) DOI PMID
[4] Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis
[ 4 ] Christopher J Black et al. (2021) DOI PMID
[5] Nutrient Intake, Diet Quality, and Diet Diversity in Irritable Bowel Syndrome and the Impact of the Low FODMAP Diet
[ 5 ] Heidi M Staudacher et al. (2020) DOI PMID
[6] A low FODMAP diet plus traditional dietary advice versus a low-carbohydrate diet versus pharmacological treatment in irritable bowel syndrome (CARIBS): a single-centre, single-blind, randomised controlled trial
[ 6 ] Sanna Nybacka et al. (2024) DOI PMID
[7] A Very Low-carbohydrate Diet Improves Symptoms and Quality of Life in Diarrhea-Predominant Irritable Bowel Syndrome
[ 7 ] Gregory L Austin et al. (2009) DOI PMCID PMID
[8] Bran and irritable bowel syndrome: time for reappraisal
[ 8 ] C Y Francis et al. (1994) DOI PMID
[9] The effect of fiber supplementation on irritable bowel syndrome: a systematic review and meta-analysis
[ 9 ] Paul Moayyedi et al. (2014) DOI PMID
[10] The Gut-Brain Axis in Irritable Bowel Syndrome: Implementing the Role of Microbiota and Neuroimmune Interaction in Personalized Prevention—A Narrative Review
[ 10 ] Fatima Soufan et al. (2025) DOI PMCID PMID
[11] Gut Microbial Dysbiosis in the Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Case-Control Studies
[ 11 ] Lin Wang, Nuha Alammar et al. (2020) DOI PMID
[12] Intestinal barrier dysfunction in irritable bowel syndrome: a systematic review
[ 12 ] Nikita Hanning et al. (2021) DOI PMCID PMID
[13] Abnormal intestinal permeability in subgroups of diarrhea-predominant irritable bowel syndromes
[ 13 ] Simon P Dunlop et al. (2006) DOI PMID
[14] Ketogenic Diets Alter the Gut Microbiome Resulting in Decreased Intestinal Th17 Cells
[ 14 ] Qi Yan Ang et al. (2020) DOI PMCID PMID
[15] The ketogenic diet: its impact on human gut microbiota and potential consequent health outcomes: a systematic literature review
[ 15 ] Leslyn Rew et al. (2022) DOI PMCID PMID
[16] The Influence of Ketogenic Diet on Gut Microbiota: Potential Benefits, Risks and Indications
[ 16 ] Andrea Santangelo et al. (2023) DOI PMCID PMID
[17] Intermittent fasting modulates the intestinal microbiota and improves obesity and host energy metabolism
[ 17 ] Xiangwei Hu et al. (2023) DOI PMCID PMID
[18] Fasting, Circadian Rhythms, and Time-Restricted Feeding in Healthy Lifespan
[ 18 ] Valter D Longo et al. (2016) DOI PMCID PMID