Small Intestinal Bacterial Overgrowth, or SIBO, is a condition in which normal bacteria colonize the small intestine — where they do not belong — causing uncomfortable, sometimes painful gastrointestinal symptoms, the most common of which is chronic bloating. (Other symptoms commonly overlap with Irritable Bowel Syndrome, including diarrhea/constipation, abdominal pain, cramping, gas, bloating, nausea, and belching.) If you have an IBS diagnosis, you may very well have SIBO; 60–70% of those with IBS have SIBO. In terms of prevalence, 30–45 million Americans have IBS, and 20–35 million have SIBO. Clearly these conditions are quite common. Nonintestinal symptoms can also be present, such as migraines, fatigue, depression or anxiety, and brain fog. If you would like to learn more background, please see my previous articles on SIBO.

This space is devoted to SIBO risk factors and underlying causes, because finding and addressing these is key to successful SIBO management. Two-thirds of SIBO cases are chronic relapsing, usually due to the underlying cause not being addressed. Understanding risk factors also may very well be the key to figuring out that you have SIBO, which is not always easy, as the condition is still becoming known in the medical community.

Risk Factors

There are many risk factors for SIBO, the most common of which is food poisoning. Other broad categories of risk factors include diseases, surgeries or injuries, medications, and lifestyle. All of these can cause failures in our bodies’ protective mechanisms that would normally prevent us from getting SIBO. These all can lead to the physiological underlying causes, or the structural or functional changes that actually take place in the body, which then can lead to SIBO.

Examples of Risk Factors

In the case of food poisoning, bacteria can release toxins that attack our own intestinal cells, leading to a deficient Migrating Motor Complex, which is explained later in the article. If you had a bout of food poisoning and never felt the same afterwards, it could be SIBO. (Symptoms can take up to six months to manifest.) Other diseases include C. difficile infection, Ehlers-Daniels syndrome, Lyme disease and coinfections, systemic sclerosis, hypothyroidism, diabetes, gastroparesis, immune deficiency, liver disease, muscular dystrophy, Parkinson’s, POTS, parasites, inflammatory bowel disease, abdominal cancer, endometriosis, and appendicitis, to name a few.

Surgeries can include abdominal or pelvic surgery (for example appendectomy or gastrectomy, or anything that alters intestinal anatomy).

Injuries can include those to the abdominal or pelvic area from car or sports accidents, for example; radiation to the abdominal area; internal hemorrhage; or traumatic brain or spinal injuries, such as whiplash. You do not have to have had impact to the head or be knocked out.

Medications are also considered a SIBO risk factor. These include antibiotics, opiates, proton pump inhibitors (PPIs), immunosuppressants, alcohol, muscle relaxants, and intravenous feeding.

Toxic mold exposure and stress can also be contributing risk factors.

Underlying Causes (when structural or functional protections go wrong)

The small intestine has many structural and functional mechanisms that protect us from SIBO. SIBO risk factors, such as the ones listed above, are what cause these mechanisms to malfunction; the first four, below, are more risk factors, while the last two are truer underling causes.

1. Hydrochloric acid. Our stomachs naturally contain this acid to help us digest food. This acid is also strong enough to kill most microorganisms. 2. Bile. Bile is secreted by the gallbladder to help us break down fats in our food. Bile also normally kills or halts growth of bacteria. 3. Digestive enzymes. These are secreted in various parts of the digestive tract. They also kill or arrest growth of bacteria. 4. Immune system. This is an obvious one. When the immune system fails, bacteria are not targeted. 5. Normal small intestine anatomy. While a healthy small intestine allows everything inside to flow through in a downward direction, intestinal blockages can impede this flow. Examples include adhesions, strictures, tumors, compression, twists, fistulas, and blind loops in the small intestine. Changes to the ileocecal valve can also allow backflow of large intestine contents, including bacteria, into the small intestine, where they do not belong. 6. Migrating Motor Complex or MMC. This is the downward, propulsive, repetitive wave-like motion that pushes gastric and intestinal contents down the intestinal tract. It happens rhythmically after a certain amount of fasting time. When either normal anatomy or the MMC are disrupted enough, SIBO is likely to occur as bacteria lingers too long in the small intestine. (More on the MMC in a future article.)

While this may all sound gloom and doom, remember that SIBO is very manageable with herbal or prescription antibiotics, supplements (for example those that support the MMC and digestion), lifestyle changes, and dietary restrictions. While not all underlying causes or risk factors can be changed, many of them can. Even when an underlying risk factor like a disease cannot be made to go away, SIBO can certainly be managed to get symptomatic relief, at minimum. This summary of risk factors is to help you identify them in yourself or in your loved ones, so that more people can get the help that they need in order to finally find relief from symptoms they may have thought were irremediable.

The information provided in this article is intended for general use only and is not to be used in place of medical advice from a licensed health professional.