What is SIBO? Understanding Small Intestinal Bacterial Overgrowth
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If you’ve been dealing with bloating, abdominal discomfort, gas, or irregular bowel movements, you may have heard the term SIBO—but what exactly is it? In this blog, we’ll dive into Small Intestinal Bacterial Overgrowth (SIBO): what it is, what causes it, and how it impacts your digestive health. Whether you’re dealing with symptoms or just curious to learn more, this guide will provide you with a thorough understanding of SIBO.
What Is SIBO?
SIBO stands for Small Intestinal Bacterial Overgrowth. It refers to a condition in which an abnormal increase in the number of bacteria occurs in the small intestine. Normally, the small intestine has relatively few bacteria compared to the large intestine, where most of your gut bacteria reside. However, in SIBO, the balance is disrupted, and there is an overgrowth of bacteria in the small intestine.
In a healthy gut, the small intestine is responsible for the breakdown of food and absorption of micro- and macronutrients. If something disrupts the natural movement of food through the intestines, better known as gut motility, bacteria can grow and thrive in the small intestine. The problem with this overgrowth is that these bacteria start to interfere with the normal digestive process. They can cause digestive symptoms, malabsorption of nutrients, and other health issues.
Causes of SIBO
Several factors can contribute to the development of SIBO. Some of the most common causes include:
Impaired Gut Motility
The small intestine relies on coordinated muscle contractions to clear out food and bacteria through the digestive process. If motility is altered, bacteria can remain in the small intestine longer, leading to overgrowth.
Structural Issues
Abnormalities in the small intestine, such as intestinal strictures (narrowing), diverticula (out-pouches), or previous surgeries, can create areas where bacteria can accumulate and grow.
Weakened Immune System
The immune system plays a vital role in keeping gut bacteria in check. People with a compromised immune system (due to conditions like HIV/AIDS or autoimmune diseases) are more susceptible to developing SIBO.
Antibiotic Use
Overuse of antibiotics can disrupt the natural balance of gut bacteria. While antibiotics are used to kill harmful bacteria, they also affect beneficial bacteria, which can make it easier for harmful bacteria to proliferate in the small intestine.
Low Stomach Acid (Hypochlorhydria)
Stomach acid helps to kill harmful bacteria and maintain a healthy balance of gut flora. Conditions like acid reflux or gastric acid suppression (from proton pump inhibitors or H2 blockers) can reduce stomach acid, increasing the risk of bacterial overgrowth in the small intestine.
Other Digestive Disorders
Conditions such as IBS, Celiac disease, Crohn’s disease, and type 1 diabetes can increase the risk of developing SIBO. These conditions may impact digestion, gut motility, or immune function, creating an environment conducive to bacterial overgrowth.
Symptoms of SIBO
The symptoms of SIBO can vary widely, but they often include some combination of the following:
Bloating
Excessive gas or flatulence
Abdominal pain or discomfort
Diarrhea or constipation, or alternating between the two
Nausea
Indigestion or heartburn
Fatigue
Unexplained weight loss or difficulty gaining weight
Malnutrition (due to poor nutrient absorption)
Because these symptoms can overlap with other digestive conditions, such as Irritable Bowel Syndrome (IBS) or inflammatory bowel disease (IBD), SIBO is sometimes misdiagnosed. That’s why it’s important to seek a proper diagnosis from a healthcare professional if you’re experiencing persistent digestive symptoms.
How Is SIBO Diagnosed?
Diagnosing SIBO can be challenging, but the most common diagnostic tool for SIBO is a breath test. There are two main types of breath tests used to diagnose SIBO:
Lactulose Breath Test: Lactulose is a type of sugar that is not absorbed by the body. When bacteria in the small intestine ferment lactulose, it produces gases such as hydrogen and methane, which are then measured in the breath.
Glucose Breath Test: Similar to the lactulose test, the glucose breath test uses glucose to measure the gases produced by bacteria. It’s considered a bit more accurate in identifying SIBO related to hydrogen production.
How Is SIBO Treated?
The treatment for SIBO typically involves a multi-faceted approach:
Antibiotics: The primary treatment for SIBO is the use of antibiotics to reduce the bacterial overgrowth in the small intestine.
Dietary Changes: A Low FODMAP diet is commonly recommended to help manage SIBO symptoms. FODMAPs are a group of short-chain carbohydrates that are poorly absorbed in the small intestine and can ferment, exacerbating SIBO symptoms. A Specific Carbohydrate Diet (SCD) or an Elemental Diet may also be used for more severe cases.
Herbal Remedies: Some people with SIBO find relief using herbal antimicrobials, such as oregano oil, garlic extract, or berberine. These may help reduce bacterial overgrowth without the use of antibiotics.
Addressing Underlying Causes: If there are underlying conditions contributing to SIBO, such as gastric acid suppression or motility issues, treating these causes will be crucial for long-term management.
SIBO is a complicated condition that’s often misinterpreted, but with the right diagnosis and treatment, it can be effectively managed. As a team of registered dietitians, we at Katie Chapmon Nutrition, can play a key role in helping you manage SIBO by guiding you through tailored dietary adjustments and strategies to reduce symptoms like bloating, abdominal discomfort, and irregular bowel movements. By working with us, you can restore balance to your gut, alleviate distressing symptoms, and improve your overall digestive health. We aim to come alongside you to support you in finding relief and improving your well-being.
Interested in learning more about SIBO or have you received a recent diagnosis and in need of further support?
We’d love to work with you! Schedule a complimentary Meet + Greet session. We look forward to finding individualized solutions to fit your needs.
Published: January 20th, 2025
This blog post was written by Amanda Sikkema, a dietitian at Katie Chapmon Nutrition. Amanda works with clients virtually and is accepting new clients.
