Could SIBO Be Causing Your Digestive Issues?
The human digestive system is a complex and intricate network of organs working in harmony to break down food, absorb nutrients, and eliminate waste. However, disruptions in this delicate balance can lead to various gastrointestinal issues, one of which is small intestinal bacterial overgrowth (SIBO). In this blog article, we will dive into the details of SIBO, exploring its causes, symptoms, diagnosis, and treatment options.
Understanding Small Intestinal Bacterial Overgrowth (SIBO)
SIBO is a condition characterized by an abnormal increase in the number of bacteria in the small intestine. Normally, the small intestine harbors a limited amount of bacteria, as the majority of these microorganisms reside in the large intestine. In SIBO, the bacteria within the large intestine are thought to migrate to the small intestine. When an overgrowth occurs in the small intestine, it can lead to a range of digestive issues, nutritional deficiencies, and systemic problems.
SIBO is associated with the production and accumulation of various gases in the gastrointestinal tract. These gases play a significant role in the symptoms experienced by individuals with SIBO and can be measured in diagnostic tests. These gases are byproducts of the fermentation of carbohydrates by intestinal bacteria in the small intestine. The primary gases involved in SIBO include hydrogen (H2), methane (CH4), and sometimes, hydrogen sulfide (H2S).
Understanding the different gases involved in SIBO is crucial for both diagnosis and treatment. Breath tests that measure hydrogen and methane levels provide valuable insights into the types of bacteria present in the small intestine. Additionally, the specific gas profile can offer clues about the predominant symptoms experienced by individuals with SIBO, such as diarrhea (associated with hydrogen) or constipation (associated with methane).
Let's discuss each of these gases and their implications in SIBO:
Hydrogen (H2):
How It's Produced: One of the key features of SIBO is the excessive production of hydrogen gas by bacteria in the small intestine. This occurs as a result of bacterial fermentation of undigested carbohydrates, which leads to the release of hydrogen. The microbial composition in SIBO can be diverse, but certain bacterial species are known to be associated with hydrogen production including E. coli, Klebsiella, Citrobacter, Enterococcus, and Bacteroides.
Breath Test Significance: The hydrogen breath test is a common diagnostic tool for SIBO. In this test, patients consume a substrate (usually lactulose or glucose), and the subsequent measurement of hydrogen levels in the breath can indicate bacterial overgrowth in the small intestine.
Methane (CH4):
How It's Produced: Methane is another gas produced by certain types of bacteria during the fermentation of carbohydrates. Some microorganisms, particularly Methanobrevibacter smithii, can convert hydrogen produced by other bacteria into methane. Elevated methane levels are associated with a subtype of SIBO referred to as methanogen overgrowth.
Breath Test Significance: Methane is measured alongside hydrogen in breath tests for SIBO. Individuals with elevated methane levels may experience constipation and delayed transit through the digestive tract.
Hydrogen Sulfide (H2S):
How It's Produced: While less commonly measured in traditional breath tests, hydrogen sulfide is another gas that may be produced by certain bacteria in the small intestine. It is associated with the breakdown of sulfur-containing amino acids in the diet.
Clinical Significance: Elevated levels of hydrogen sulfide may contribute to symptoms such as abdominal pain, bloating, and diarrhea. Research on hydrogen sulfide in the context of SIBO is still evolving.
Signs & Symptoms of SIBO
SIBO manifests through a variety of symptoms, and these can vary from mild to severe. Some common symptoms include:
Non-specific symptoms such as abdominal pain, distention, gas, nausea, indigestion, constipation, and diarrhea
An uncomfortable feeling of fullness or gas immediately after eating
Bloating worse at the end of the day
Digestive symptoms that improve on a low FODMAP diet
Digestive symptoms that improve after antibiotic treatment
Digestive symptoms that worsen after taking probiotics
Digestive symptoms that worsen after eating healthier foods like vegetables
Nutritional deficiencies despite eating a well-balanced diet
Why Does SIBO Happen?
Several factors can contribute to the development of SIBO, and these often involve disruptions in the normal functioning of the digestive system. Some common causes include:
Impaired Motility: The digestive tract is always working, even during a fasted state. This constant activity can be attributed to the migrating motor complex (MMC). The MMC is a series of coordinated contractions that sweep through the small intestine, preventing the accumulation of bacteria. Those with IBS, Crohn’s disease, ulcerative colitis, gastroparesis, and thyroid disease are likely affected by impaired motility.
Low Stomach Acid Levels: Adequate stomach acid is crucial for killing bacteria that enter the digestive system. Conditions like achlorhydria or the use of acid-suppressing medications can reduce stomach acid levels, making it easier for bacteria to migrate into the small intestine.
Immune System Dysfunction: A compromised immune system can fail to regulate bacterial overgrowth in the small intestine effectively. Secretory immunoglobulin A (IgA) is an essential component of the mucosal immune system, providing a first line of defense against pathogens in the gastrointestinal tract. It helps to neutralize and eliminate bacteria before they can adhere to the intestinal lining. A compromised immune system may result in reduced production of secretory IgA. Lower levels of this protective antibody can diminish the ability to control bacterial growth in the small intestine, contributing to SIBO. Certain individuals who take immune-suppressing medications may be more susceptible to developing SIBO due to lower immune response.
Food Poisoning: While food poisoning itself does not directly cause SIBO, it can contribute to the development of SIBO in some cases. The link between food poisoning and SIBO is often associated with the disruption of the normal balance of gut microbiota and alterations in gut motility.
Structural Abnormalities: Certain structural abnormalities, such as strictures or adhesions in the small intestine, can create stagnant areas where bacteria can overgrow. This can even result from the scar tissue left behind from a C-section, endometriosis, hysterectomy, or tummy tuck.
Dysfunctional Ileocecal Valve: The ileocecal valve acts as a barrier between the small and large intestines, preventing the backflow of digested food into the small intestine. If the ileocecal valve is dysfunctional, it may fail to maintain this barrier effectively. This can allow bacteria from the large intestine to migrate into the small intestine, contributing to overgrowth.
How to Test for SIBO
A non-invasive breath test that measures both hydrogen (H2) and methane (CH4) gas is the best way to confirm the presence and severity of SIBO. Hydrogen sulfide-producing bacteria is a newer concept regarding SIBO and testing isn’t readily available yet.
There are a few different breath testing options for detecting SIBO. Clinicians have the option of a 2 or 3-hour SIBO breath test. The 3-hour SIBO test provides insight into gas levels over a longer time frame and is the best option for those with constipation. Clinicians also have the option of choosing between a glucose or lactulose solution, which is not to be confused with the sugar found in milk called lactose. Humans cannot digest or absorb lactulose, only bacteria have the proper enzymes to do so. Since it is not absorbed, lactulose travels the entire length of the intestine, revealing SIBO at all portions of the small intestine including the lower part where it most commonly occurs. Glucose gets rapidly absorbed by the body and may not reach the furthest part of the small intestine. For these reasons, the 3-hour lactulose breath test is often the preferred testing method.
How Do You Get Rid of SIBO?
Managing SIBO involves a multifaceted approach aimed at reducing bacterial overgrowth, relieving symptoms, and addressing underlying causes. That said, there are two phases of SIBO treatment: the eradication phase and the relapse prevention phase. The goal of the eradication phase is to kill off the problematic bacteria, reduce symptoms, and achieve a negative SIBO retest. SIBO can be eradicated with either traditional antibiotics or natural antimicrobial agents. The low FODMAP diet is often recommended during the eradication phase to reduce the intake of fermentable carbohydrates that can fuel bacterial overgrowth. The goal of the relapse prevention phase is to correct the underlying cause(s) of SIBO, prevent recurrence, heal the gut lining, rebalance the gut microbiome, and optimize digestive health. SIBO has a 45% recurrence rate by 9 months, especially if the underlying cause is not corrected. Chronic or relapsing SIBO occurs in two-thirds of cases, requiring ongoing management. If left untreated, SIBO can lead to complications such as malabsorption and intestinal permeability aka “leaky gut”.
Small intestinal bacterial overgrowth is a complex and challenging condition that can significantly impact an individual's quality of life. Understanding its causes, recognizing its symptoms, and pursuing an effective treatment plan tailored to each patient are crucial steps in managing SIBO. With a comprehensive approach that includes antimicrobials, dietary modifications, and lifestyle changes, individuals with SIBO can regain control of their digestive health and improve their overall well-being. Seeking guidance from a qualified healthcare professional trained in SIBO detection and management is essential for ensuring a path toward long-term relief from SIBO symptoms.
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Disclaimer: Not medical advice. For educational purposes only. Please consult with your doctor before making any changes.