Why Do People Get IBS? Understanding the Root Causes of Irritable Bowel Syndrome

Introduction

Irritable Bowel Syndrome (IBS) affects an estimated 10–15% of people worldwide, yet its causes are often misunderstood or dismissed. If you’ve been told “it’s all in your head” or handed a generic low-FODMAP diet without answers, you’re not alone—and you deserve better.

IBS is real. And there are real, root causes behind your symptoms.

In functional medicine, we treat IBS not as a label to manage—but as a symptom of deeper imbalances that can be uncovered, addressed, and often reversed.

In this article, we’ll break down:

  • What IBS really is
  • The most common underlying causes
  • Why conventional approaches often fall short
  • Natural and functional strategies to restore gut health

What Is IBS?

IBS (Irritable Bowel Syndrome) is a functional gastrointestinal disorder marked by chronic digestive symptoms without visible structural abnormalities on colonoscopy or imaging.

Common IBS symptoms include:

  • Bloating
  • Abdominal pain or cramping
  • Diarrhea (IBS-D), constipation (IBS-C), or alternating (IBS-M)
  • Gas or urgency
  • Feeling of incomplete evacuation

The root cause? That’s where things get complex—and where functional medicine shines.

Top Root Causes of IBS

Let’s explore the key drivers that contribute to IBS, based on both research and clinical experience.

1. Gut-Brain Axis Dysregulation

Your gut and brain are in constant communication via the gut-brain axis—a bidirectional network involving the vagus nerve, neurotransmitters, and the enteric nervous system.

Stress, trauma, or chronic anxiety can disrupt this connection and lead to:

  • Hypersensitivity to normal gut activity (called visceral hypersensitivity)
  • Altered motility (causing diarrhea or constipation)
  • Increased pain perception

IBS is often triggered or worsened by stress, and may coexist with anxiety, depression, or PTSD.

2. Small Intestinal Bacterial Overgrowth (SIBO)

SIBO is one of the most overlooked causes of IBS. It occurs when excess bacteria grow in the small intestine, fermenting food and producing gas, inflammation, and motility issues.

SIBO can cause:

  • Bloating (often within 30–90 minutes after meals)
  • Constipation or diarrhea
  • Fatigue and brain fog
  • Food intolerances (especially to fiber, starch, or probiotics)

Studies show that up to 70% of IBS patients may have SIBO, making it a major target for testing and treatment.

3. Post-Infectious IBS

After a bout of food poisoning or stomach flu, some people develop IBS symptoms that never go away. This form of IBS is linked to:

  • Disrupted gut motility
  • Damage to the gut lining
  • Autoimmunity to enteric nerves

This can trigger diarrhea-predominant IBS that persists long after the infection clears.

4. Gut Dysbiosis

Your gut is home to trillions of bacteria. When this ecosystem becomes imbalanced—too many “bad” bugs, not enough “good” ones—it can lead to:

  • Increased inflammation
  • Bloating and gas
  • Mucosal irritation
  • Leaky gut and immune reactivity

Dysbiosis may be caused by:

  • Antibiotic use
  • Processed food
  • Chronic stress
  • Infections or toxins

Comprehensive stool testing can help identify bacterial imbalances and tailor treatment.

5. Food Sensitivities

Many people with IBS react to specific foods—not because of allergies, but due to immune or enzymatic intolerances.

Common culprits include:

  • Gluten
  • Dairy (especially lactose or casein)
  • Eggs
  • Soy
  • FODMAPs (fermentable sugars in certain fruits, grains, and vegetables)

Removing food triggers for a short time—while healing the gut—can significantly reduce IBS symptoms.

6. Leaky Gut (Intestinal Permeability)

When the gut lining is damaged, it becomes more permeable, allowing toxins, bacteria, and undigested food into the bloodstream. This leads to:

  • Immune activation
  • Low-grade inflammation
  • Heightened food reactions
  • Bloating and pain

Leaky gut is both a driver and consequence of IBS and is critical to address in long-term healing.

7. Bile Acid Malabsorption

In some cases, excess bile acids entering the colon can cause diarrhea, urgency, and abdominal pain—especially in IBS-D.

This condition is often missed on standard workups but can be managed with bile acid binders and targeted testing.

8. Hormonal Imbalances

Many women with IBS notice symptoms worsen around their menstrual cycle. That’s because:

  • Estrogen and progesterone influence gut motility and sensitivity
  • Hormonal shifts can trigger bloating, cramping, or constipation
  • Thyroid dysfunction, PCOS, or perimenopause may also contribute

Addressing hormone health is often a missing piece of IBS treatment.

9. Chronic Stress and Nervous System Dysregulation

Chronic fight-or-flight stress:

  • Slows digestion
  • Increases intestinal permeability
  • Impacts microbiome balance
  • Heightens pain perception

Calming the nervous system is just as important as healing the gut. This might include:

  • Vagus nerve stimulation
  • Breathwork and meditation
  • Acupuncture
  • Adaptogenic herbs

Why Conventional Treatments Often Fall Short

Most standard treatments for IBS include:

  • Fiber supplements or laxatives
  • Antispasmodics
  • Antidepressants (for gut-brain regulation)
  • Low-FODMAP diet

While these may provide temporary relief, they rarely address the root cause, leaving patients cycling through symptoms without long-term resolution.

Functional Medicine Approach to IBS Relief

At Sheen Vein & Cosmetics, we use a comprehensive, root-cause approach to address IBS from every angle.

Our 4R strategy often includes:

✅ Remove

  • Food triggers
  • Gut infections (SIBO, parasites, candida)
  • Toxins or medications disrupting digestion

✅ Replace

  • Digestive enzymes
  • Stomach acid (if low)
  • Bile salts (if bile flow is sluggish)

✅ Reinoculate

  • Probiotics (strain-specific)
  • Prebiotic fiber (as tolerated)

✅ Repair

  • Gut-healing nutrients: L-glutamine, zinc carnosine, collagen, aloe vera
  • Anti-inflammatory herbs and targeted support

We also assess:

  • Stress levels and trauma history
  • Sleep quality and circadian rhythm
  • Hormone balance
  • Thyroid function
  • Micronutrient status

Conclusion: IBS Isn’t Just in Your Head—It Has a Root Cause

If you’ve been told to “just live with it” or put on yet another restrictive diet, know this: IBS has a cause, and healing is possible. Whether it’s SIBO, dysbiosis, leaky gut, stress, or food sensitivities, we can uncover and address the true drivers behind your symptoms.

You deserve answers. You deserve relief. And you don’t have to manage IBS forever.

Ready to Finally Get to the Root of Your IBS?

At Sheen Vein & Cosmetics, our functional medicine team offers in-depth evaluations and customized protocols to help you heal your gut, calm your system, and regain control of your life.

📞 Call or book your gut health consultation today.

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