Different Types of Small Intestinal Overgrowth (SIBO)

SIBO, or Small Intestinal Bacterial Overgrowth, is a growing health concern affecting many people. It is caused by an overgrowth of bacteria in the small intestine, leading to a variety of uncomfortable and debilitating symptoms. SIBO can be caused by various underlying conditions, and is classified into three distinct types: hydrogen-dominant SIBO, methane-dominant SIBO, and mixed-dominant SIBO. Each type of SIBO is associated with a unique set of symptoms and can be treated with a variety of therapies. In this article, we will explore the different types of SIBO and their associated symptoms, as well as the treatments available for each type. With the right testing and approach, individuals with SIBO can find relief from their symptoms and lead healthier lives. What is SIBO? SIBO stands for Small Intestinal Bacterial Overgrowth. When bacteria grow in the small intestine, SIBO can occur. SIBO is a condition that affects the intestinal tract. It causes digestive issues like abdominal pain, diarrhea, and bloating. SIBO occurs when normal bacteria, which is normally found in the large intestine, migrates to the small intestine which should be largely sterile. The small intestine is where food is broken down into nutrients. If SIBO is not treated, it can lead to more serious health conditions, like anemia, liver disease, and a whole host of symptoms related to a leaky gut. SIBO is a growing health concern affecting many people. SIBO can be caused by various underlying conditions, and is classified into three distinct types: hydrogen-dominant SIBO, methane-dominant SIBO, and mixed-dominant SIBO. Each type of SIBO is associated with a unique set of symptoms and can be treated with a variety of therapies. In this article, we will explore the different types of SIBO and their associated symptoms, as well as the treatments available for each type.  Overview of Hydrogen-Dominant SIBO Hydrogen-dominant SIBO is caused by a bacterial overgrowth of species that produce hydrogen gas, such as E. coli and Klebsiella pneumoniae. It is the most common form of SIBO, affecting approximately 60% of people with SIBO. Hydrogen-dominant SIBO has several potential triggers, and is more common in individuals who have been prescribed antibiotics and/or have gastrointestinal disorders. Hydrogen-dominant SIBO is primarily diagnosed through hydrogen breath tests, as it is almost impossible to detect through other forms of testing.  Overview of Methane-Dominant SIBO Methane-dominant SIBO is caused by a bacterial overgrowth of species that produce methane gas, such as Bacteroides species and Fusobacterium nucleatum. It is the least common form of SIBO, affecting approximately 25% of people with SIBO. Methane-dominant SIBO has several potential triggers and is more common in individuals who have undergone gastrointestinal surgery. Methane-dominant SIBO can be diagnosed with hydrogen breath tests using different substrates such as lactulose and glucose.  Overview of Mixed-Dominant SIBO Mixed-dominant SIBO is caused by a combination of species producing hydrogen and methane gas. It is the second most common form of SIBO.  Like the other types of SIBO, mixed-dominant SIBO can be diagnosed through testing using lactulose or glucose or a combination of the both.  Hydrogen sulfide SIBO Hydrogen sulfide SIBO is a type of small intestinal bacterial overgrowth (SIBO) caused by the excessive production of hydrogen sulfide (H2S) in the small intestine. This condition is linked to several digestive disorders, including irritable bowel syndrome, leaky gut, and inflammatory bowel disease.Symptoms of hydrogen sulfide SIBO can include abdominal pain, diarrhea, constipation, bloating, flatulence, and bad breath. Treatment for hydrogen sulfide SIBO often includes antibiotics, herbal antimicrobials, probiotics, dietary changes, and lifestyle modifications. It’s important to talk to your functional medicine doctor about the best treatment option for your individual situation. With proper treatment, hydrogen sulfide SIBO can be managed and your digestive symptoms can be relieved. Common Symptoms of SIBO There are so many differnt symptoms relating to SIBO which makes it difficult to diagnose. Abdominal pain – People with SIBO may can experience abdominal pain in the upper right side of the abdomen. This pain is often described as cramping, burning, or gnawing in nature. It can be worsened by eating, and can last several hours after a meal. – Bloating – Bloating is caused by the buildup of bacterial waste products in the small intestine, which can lead to abdominal distension and pain. This is one of the most common symptoms of SIBO, occurring in around 90% of people with SIBO. – Diarrhea – Bacterial overgrowth in the small intestine can lead to a disruption of normal digestion, resulting in diarrhea – Excessive gas – People with SIBO often experience excessive gas, particularly after consuming a high-fiber diet. Excessive gas can cause abdominal distension, pain, and flatulence. While people with SIBO can experience excessive gas regardless of fiber intake, they tend to be more sensitive to it due to the presence of bacteria in the small intestine. – Iron deficiency – Iron is essential for hemoglobin production, which is responsible for transporting oxygen throughout the body. Bacterial overgrowth in the small intestine can result in iron deficiency, due to increased levels of hydrogen gas in the small intestine that inhibit iron absorption.  Nutrient malabsorption – Bacterial overgrowth in the small intestine can cause malabsorption of nutrients. This can lead to nutritional deficiencies, particularly in iron, B12, and vitamin D. This can lead to reduced immune function, headaches, and poor sleep. Diagnosing SIBO There are numerous gut tests on the market including the organic acids tests, and microbiome testing which includes tests such as the GI MAP, Genova and Doctors’ data etc. However, as good as tests as these are they only give a snapshot of the large intestine.  The gold standard of SIBO testing is a breath that will measure the levels of the different gases. however, that is not to say that a microbiome test isn’t worthwhile. At the Dublin Centre for Functional medicine, we generally recommend both and reason is that SIBO is generally an eco-system issue that starts in the large bowel. If there is a dysfunctional large bowel, this will set the stage for