It’s not clear how many people are affected by SIBO, but it can result from certain other conditions. This article will review facts and statistics for small intestinal bacterial overgrowth.
SIBO Overview
SIBO may occur in people who have had surgery on their bowels, take certain medications, or live with certain medical conditions affecting the digestive system. There is no one standardized way to test or treat SIBO. In some cases, it may be diagnosed with a breath test and treated with antibiotics.
Some of the signs and symptoms of SIBO include:
Abdominal bloating Abdominal pain Constipation Dyspepsia (indigestion) Gas and flatulence Diarrhea Fatigue Malabsorption (not absorbing nutrients properly) Nausea Vitamin deficiencies (including iron) Weight loss
How Common Is SIBO?
SIBO is considered a common condition, but no reliable data exist on how many people are diagnosed and treated yearly. However, there is some information available on how often SIBO affects people with other digestive conditions.
One study found that for people with inactive Crohn’s disease (meaning that various clinical tests showed no sign of disease activity in people previously diagnosed with the condition), 16.8% had SIBO. Crohn’s disease is an inflammatory bowel disease (IBD) that affects the lining of the digestive tract.
Another small study looked at the rate of SIBO in people who have celiac disease (an autoimmune condition triggered by gluten) and those who have irritable bowel syndrome (IBS), an intestinal disorder causing cramps, pain, diarrhea, and gas, compared to people without a digestive condition. It showed that in those with celiac disease, 13% had SIBO, and in people with IBS, 67% were diagnosed with SIBO.
SIBO by Ethnicity
There is little data on the prevalence of SIBO across ethnicities in the United States. However, studies in different countries or areas of the world that include people with IBS show various rates of SIBO in those populations.
The rates of SIBO in people with IBS across studies are:
Canada: 10%Europe: 23%India: 14%Iran: 37%Southeast Asia: 37%United States: 55%
SIBO by Age and Gender
Not much is known about how many people are affected by SIBO. Not only is it a condition related to other disorders, but there’s also not complete agreement among healthcare providers on how to diagnose and treat it.
What has been shown is that anywhere from 13% to 35% of healthy people may have SIBO, depending on which test is used to diagnose the condition. Older people may be at greater risk for SIBO because they tend to have altered levels of gastric acid and may be more likely to receive a medication that increases the risk of SIBO.
Causes of SIBO and Risk Factors
SIBO might occur when the balance of the microbiome in the small bowel is disturbed by something. This can happen because of a disease, condition, medication, or surgery that affects the bowels. It can also occur with conditions that don’t directly affect the small bowel but may change the ability of the gut to regulate itself.
Several conditions are associated with SIBO. Some of the more common ones include:
Celiac disease: An autoimmune condition in which gluten protein in food triggers a reaction that damages the lining of the small intestine Cirrhosis: Scarring of the liver caused by injury or disease Crohn’s disease: Inflammation and ulcers in the lining of the digestive tract Diabetes: Inability of the body to manage blood sugar levels Gastroparesis: A disorder that causes delayed emptying of the stomach Hypothyroidism (underactive thyroid): A condition in which the thyroid gland doesn’t produce enough hormones IBS: A disorder of the gut-brain axis that causes symptoms in the lower digestive system Obesity: A condition of having excess body fat and various other signs and symptoms Radiation enteritis: A complication of radiation therapy that causes diarrhea and other symptoms in the lower digestive tract
Medications might also be a risk factor or a cause of SIBO. Medications that are associated with SIBO include:
Anticholinergics: Medications that slow the contractions of smooth muscles Opioids: Pain medications that affect the digestive system Proton pump inhibitors: Used to treat heartburn or gastroesophageal reflux disease (GERD)
What Are the Mortality Rates for SIBO?
SIBO tends to be a complicating factor that goes along with other conditions. For that reason, it’s not considered a fatal disorder. But it is possible that it leads to worse outcomes for people already managing certain serious conditions.
For instance, one study on people with heart failure—a condition in which the heart doesn’t pump enough blood to meet the body’s needs—showed that SIBO is common and increases poor outcomes, like being readmitted to the hospital or risk of death. The authors of this study suggest that it’s worth treating SIBO in people with heart failure.
However, there’s little other data to guide decisions on who should be tested and treated for SIBO and how it might affect the risks of complications. The decision to test and treat for SIBO will be made between healthcare providers and patients.
Screening and Early Detection for SIBO
It can be challenging to diagnose SIBO because there are no accepted guidelines on who to test for SIBO and when. It is known that SIBO is common in people with certain conditions, such as those who live with Crohn’s disease or IBS.
However, many of the symptoms of SIBO are nonspecific and are similar to the symptoms of other conditions. People may need to talk with a healthcare provider about additional testing if a condition is being treated, but symptoms such as bloating, pain, and diarrhea are not improving.
Some of the ways to test for SIBO include:
Breath tests, which are noninvasive and measure the hydrogen level during exhalationJejunal aspiration, which takes place during an endoscopy (in which a flexible tube is inserted into the body to take images)Trialing a medication to treat SIBO and tracking results
Summary
SIBO is a common condition, but how many people it affects is still not well understood. It can result as a complication of various other diseases and conditions. People may want to seek a diagnosis or treatment if they are in a higher risk group and suspect SIBO.