Many patients experience ongoing digestive issues such as bloating, abdominal discomfort, and unpredictable bowel habits yet struggle to find clear answers. One underlying cause that is often overlooked is Small Intestinal Bacterial Overgrowth (SIBO).
This condition affects the small intestine, disrupts normal digestion, and can impact overall wellness in surprising ways. Understanding what SIBO is, why it develops, and how it can be treated is key to restoring gut health and improving long term wellbeing.
What Is Small Intestinal Bacterial Overgrowth?
Small Intestinal Bacterial Overgrowth, or SIBO, occurs when excessive bacteria grow in the small intestine. Normally, most bacteria live in the large intestine, where they aid digestion and maintain balance. The small intestine, by contrast, should contain only small amounts of bacteria to allow proper absorption of nutrients.
When bacteria begin to overgrow in the small intestine, they ferment food too early, leading to uncomfortable symptoms, malabsorption of vitamins and minerals, and even systemic health issues. SIBO is not just a digestive disorder, it can affect energy levels, metabolism, skin, and weight.
Common Symptoms of SIBO
SIBO symptoms can mimic other conditions like irritable bowel syndrome, making it difficult to diagnose without testing. Patients often report:
Persistent bloating and abdominal distension, often worse after meals
Excessive gas, belching, or flatulence
Abdominal pain or cramping
Chronic diarrhea, constipation, or alternating between both
Unexplained fatigue and brain fog
Nutrient deficiencies, especially vitamin B12, iron, and fat soluble vitamins
Unexplained weight changes such as gain or loss
If you have been told you have IBS but treatments have not worked, it may be worth asking your doctor about SIBO testing.
Why SIBO Matters for Whole Body Health
The small intestine is where the majority of nutrient absorption takes place. When bacteria overgrow here, they interfere with the body’s ability to absorb proteins, fats, carbohydrates, and vitamins. Over time, this can contribute to malnutrition, weakened immunity, skin conditions, and metabolic problems.
SIBO also produces excess gases such as methane and hydrogen, which can further slow gut motility, create inflammation, and disrupt normal digestive rhythms. Beyond the gut, these effects may influence hormone balance, increase systemic inflammation, and even contribute to stubborn weight gain.
Causes and Risk Factors for SIBO
Several factors can set the stage for bacterial overgrowth in the small intestine:
Low stomach acid: Stomach acid normally kills harmful bacteria. Long term use of acid suppressing medications can raise SIBO risk.
Poor gut motility: Conditions that slow digestion, such as diabetes or hypothyroidism, may allow bacteria to accumulate.
Structural changes: Scar tissue or surgeries involving the digestive tract can affect how food and bacteria move through the intestine.
Previous infections: Food poisoning or gastrointestinal infections can trigger long term gut changes that increase susceptibility.
Chronic conditions: Celiac disease, Crohn’s disease, and irritable bowel syndrome are often linked with higher rates of SIBO.
Chronic use of antibiotics, Non-steroidal anti-inflammatory medications and other drugs: disrupting the natural balance of gut bacteria, leading to the proliferation of potentially harmful microbes that can colonize the small intestine.
Diagnosis of SIBO
Doctors typically use a breath test to measure gases produced by bacteria in the small intestine. Patients drink a sugar solution, and hydrogen or methane levels are measured over several hours. Elevated readings suggest bacterial overgrowth. In some cases, stool tests or direct sampling may also be used.
Accurate diagnosis is important because treatment for SIBO is different from other digestive disorders and requires a targeted approach.
Treatment Options for SIBO
Effective treatment usually combines medical therapy, dietary adjustments, and long term strategies to prevent recurrence. Common approaches include:
Antibiotics or herbal antimicrobials: These reduce bacterial overgrowth. Rifaximin is a commonly prescribed antibiotic with good success rates. However, Rifaximin can sometimes worsen SIBO symptoms initially due to a “die-off reaction”. This happens when the bacteria die and release toxins that cause inflammation, bloating, and abdominal discomfort.
Dietary therapy: Low FODMAP or elemental diets may be used short term to reduce fermentable foods that feed bacteria.
Prokinetics: Medications or supplements that improve gut motility help keep bacteria moving into the large intestine where they belong.
Nutritional support: Supplementation may be needed to correct deficiencies, especially in B12 and iron.
Probiotics and gut healing therapies: Under medical supervision, probiotics may help restore balance and reduce recurrence.
Because SIBO often returns if underlying causes are not addressed, ongoing care and monitoring are critical.
Living with and Preventing SIBO
While SIBO can be challenging, many patients find significant relief once it is properly diagnosed and treated. Long term management often includes:
Eating smaller meals or single servings of food to reduce fermentation in the gut
Supporting gut motility through hydration, exercise, and stress management
Avoiding unnecessary antibiotic or acid reducing medication use
Working with a physician to identify underlying conditions that may contribute
Frequently Asked Questions About SIBO
Can SIBO cause weight gain?
Yes. SIBO can disrupt metabolism, increase inflammation, and affect hormones like insulin and cortisol, all of which may lead to stubborn weight gain, especially around the midsection. Some patients also experience unintended weight loss due to nutrient malabsorption.
How is SIBO diagnosed?
The most common test is a noninvasive breath test that measures hydrogen and methane gases after drinking a sugar solution. Elevated levels suggest bacterial overgrowth in the small intestine. In some cases, stool testing or small bowel sampling may be used.
Is SIBO the same as IBS?
No. While symptoms overlap, IBS is a functional bowel disorder, whereas SIBO is caused by an overgrowth of bacteria in the small intestine. Many people with IBS are later found to have SIBO, which requires different treatment.
What is the best treatment for SIBO?
Treatment depends on the individual but may include antibiotics or herbal antimicrobials, dietary therapy such as low FODMAP, probiotics, and medications to improve gut motility. Addressing underlying causes is key to preventing recurrence.
Can SIBO come back after treatment?
Yes. SIBO can recur if the root cause is not resolved. Long term management often includes diet adjustments, stress reduction, and medical guidance to support gut motility and restore balance.
The Takeaway
Small Intestinal Bacterial Overgrowth (SIBO) is a common yet underdiagnosed cause of digestive discomfort, nutrient deficiencies, and even weight management struggles. Because it overlaps with other gastrointestinal conditions, it often goes untreated for years. If you are experiencing chronic bloating, abdominal pain, or unexplained fatigue, it may be time to consider testing for SIBO.
At Dr. Fortino’s clinic, we take a comprehensive, whole body approach to gut health and weight management. By identifying root causes such as SIBO, we help patients restore balance, improve digestion, and achieve lasting wellness.