How Do I Know If I Have SIBO?

Bloated? Struggling with IBS? You May Have SIBO. Small Intestinal Bacterial Overgrowth (SIBO) is a condition where an overgrowth of bacteria accumulate in the small intestine, an area of the gastrointestinal (GI) tract that typically has relatively low bacterial concentrations compared to the colon. While bacteria are essential to digestive and immune health, an overgrowth in the wrong place can lead to widespread symptoms that impact quality of life.

What Are the Symptoms of SIBO?

It is estimated that up to 60% of people diagnosed with IBS-D have SIBO as an underlying cause.

Common symptoms include:

• Bloating (especially within 1–2 hours after eating)
• Abdominal pain or cramping
• Excessive gas or belching
• Diarrhea, constipation, or a combination of both
• Fatigue and brain fog
• Nutrient deficiencies
• Weight gain or weight loss
• Intolerance to high FODMAP foods
• Symptoms worsening with fiber and probiotics

Additionally, there are many conditions that coexist with SIBO including: MCAS, Histamine Intolerance, Chronic Fatigue, Fibromyalgia, Rosacea, Eczema, Endometriosis, Depression, and Anxiety, to name a few. Overgrowth of bacteria in the small intestine can result in a constant state of immune activation resulting in increased inflammation and increased intestinal permeability (aka leaky gut). Some of the bacteria that cause SIBO contain lipopollysaccharide (LPS) in their cells that when released, act as an inflammatory endotoxin potentially responsible for some of the extraintestinal co-occuring symptoms and conditions.

What Causes SIBO?

Food Poisoning

Gastroenteritis cause by bacteria can trigger an immune response against the enteric nervous system—the network of nerves that controls gut motility. When someone continues to experience digestive symptoms after an episode of acute food poisoning, this is often diagnosed as post-infectious IBS. The most common underlying driver is Small Intestinal Bacterial Overgrowth (SIBO), which develops when impaired motility allows bacteria to accumulate in the small intestine. Post-infectious SIBO is most often hydrogen-dominant, presenting with symptoms such as diarrhea, bloating, and sensitivity to high-FODMAP foods.

Impaired Motility

One of the most critical defense mechanisms in the small intestine is the Migrating MotorComplex (MMC)—a wave-like motion that sweeps residual food and bacteria out of the small intestine between meals. If this mechanism is slowed or disrupted (due to stress, infections, medications, anatomical restriction, or nerve damage), bacteria can begin to accumulate. Fasting between meals and overnight is a key way to ensure the MMC is activated.

Stress

This is perhaps the most common cause of SIBO because of the busy world we live in. For many people accumulated stress over time or an acute stressor can lead to impaired motility and overgrowth of bacteria in the small intestine. Dysregulation of the vagus nerve and broader parasympathetic nervous system function often plays a central role in this process.

Low Stomach Acid

Stomach acid isn’t just for digesting food—it also acts as one of the body’s first lines of defense against bacteria that enter through food or the mouth. When acid levels are low, bacteria that would normally be killed can survive and move into the small intestine, increasing the risk of SIBO. Low stomach acid can result from chronic stress, natural age-related decline, or the use of acid-reducing medications (like proton pump inhibitors).

Dysbiosis

A key part of gut health is maintaining a diverse microbiome. Diversity helps prevent any single group of organisms—whether in the small intestine or the colon—from overgrowing and disrupting normal digestion.

How Is SIBO Diagnosed?

The most common method for diagnosing SIBO is a breath test, which measures hydrogen, methane, and hydrogen sulfide gas levels after ingesting a sugar solution (typically lactulose or glucose). These gases are byproducts of bacterial fermentation. If they appear too quickly after ingestion, it indicates that bacteria are present in the small intestine where they shouldn’t be. While breath testing has limitations, it is currently the most accessible and non-invasive diagnostic method. Microbiome stool testing can be insightful when evaluating for dysbiosis that could be contributing to recurrence.

How is SIBO Treated?

In Functional Medicine, we don’t just aim to kill the overgrowth of bacteria—we aim to restore optimal function. SIBO is often recurrent if underlying causes are not addressed.

Remove Overgrowth

Depending on the severity, gasses present, and other co-occuring conditions the following may be used:

• Herbal antimicrobials like berberine, oregano oil, garlic extract, or neem
• Prescription antibiotics such as rifaximin (for hydrogen-dominant SIBO) or rifaximin +neomycin (for methane-dominant SIBO)
• Elemental diet – a short-term liquid diet that starves bacteria but nourishes the host

Restore Motility

If the MMC is not functioning well, SIBO will often return. We may recommend:

• Prokinetics – natural or pharmaceutical agents that enhance gut motility (e.g., ginger, low-dose erythromycin, or prucalopride)
• Meal spacing – waiting 4–5 hours between meals to allow the MMC to activate and 10-12 hours overnight
• Stress reduction – supporting vagal tone through deep breathing, meditation, acupuncture, yoga, or biofeedback

Rebuild Digestive Function

Support for optimal digestion might include:

• Bitters or digestive enzymes to enhance breakdown and absorption
• Hydrochloric acid (HCl) supplementation if stomach acid is low
• Chewing food entirely and in a relaxed state

Reinoculate and Rebalance the Gut

• Prebiotics
• Spore-based or targeted probiotics
• Fiber diversity to nourish good bacteria

Repair the Gut Lining and Address Root Causes

Healing the intestinal barrier is critical after SIBO treatment. This may involve:

• Support mucosal healing with nutrients like L-glutamine, zinc carnosine, and quercetin.
• Identify and address food sensitivities or intolerances that may be contributing to ongoing inflammation.
• Correct underlying factors such as structural adhesions or impaired vagal nerve tone that interfere with normal gut motility.

Equally important are sustainable lifestyle practices—mindful eating, stress reduction, and restorative sleep—all of which help create a resilient, SIBO-resistant environment.

Why Does SIBO Keep Coming Back?

One of the most frustrating aspects of SIBO is its tendency to relapse. Studies show recurrence rates of up to 45% within a year. If treatment focuses solely on antimicrobial therapy without addressing the root causes, relapse is almost inevitable.

Common relapse factors include:

• Poor compliance with dietary and lifestyle support
• Incomplete treatment of co-existing gut infections or dysbiosis
• Undiagnosed motility issues or autoimmune processes
• Inconsistent use of prokinetics after treatment
• Ongoing stressors

In Functional Medicine, we view relapse not as failure but as an important signal: something foundational still needs support.

What Role Does Diet Play in Managing SIBO?

Diet is not a cure for SIBO, but it sometimes plays a supportive role in both symptom relief and prevention of overgrowth.

Common dietary strategies include: Low FODMAP Diet. FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are fermentable carbs that feed gut bacteria. A low FODMAP diet can reduce symptoms during treatment, but it should not be followed long-term as it can reduce beneficial bacteria. A Functional Nutritionist can tailor a plan based on your microbiome.

When Should You Seek Help for Suspected SIBO?

If you experience persistent bloating, inconsistent bowel habits, or fatigue that hasn’t responded to conventional care—or if you’ve been diagnosed with IBS without clear answers—it’s worth exploring SIBO with a Functional Medicine practitioner.

Schedule an appointment with Vida’s Functional Medicine Primary Care Concierge team for a personalized approach to your health!

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