SIBO is extremely common in people with IBS. Learn what SIBO is, how it’s diagnosed, and the different treatment options available.
Small intestinal bacterial overgrowth (SIBO) is extremely common in people with irritable bowel syndrome (IBS). In fact, a systematic review and meta-analysis published in 2020 found that up to 35.5% of people with IBS also had SIBO. If you’re living with IBS and aren’t seeing the symptom relief you’d like with diet alone, it may be worth investigating whether you have SIBO.
Today, we’ll review what SIBO is, how it’s diagnosed, and the different treatment options available to you.
What is SIBO?
SIBO refers to an imbalance in the microorganisms in your small intestine. While it’s normal and healthy to have some bacteria in the small intestine, when too many bacteria or the wrong kinds of bacteria are present, it can lead to uncomfortable gut symptoms.
SIBO vs. IMO
When we talk about SIBO, we’re actually talking about two different conditions – SIBO and IMO.
IMO, or intestinal methanogen overgrowth, was previously known as methane-dominant SIBO (the terminology changed in January 2020). It is strongly more strongly associated with constipation-predominant IBS (IBS-C).
SIBO is typically referred to as hydrogen-dominant SIBO, but it can be a generic term used to describe both bacterial and methanogen overgrowth. It is more strongly associated with diarrhea-predominant IBS (IBS-D).
What are the symptoms of SIBO?
SIBO symptoms can be similar to other gut conditions like IBS. Some of the most common symptoms include:
- Belly pain
- Belly distension
- Diarrhea (usually associated with hydrogen-dominant SIBO)
- Constipation (usually associated with methanogen overgrowth)
- Unintentional weight loss
- Fat malabsorption
- Vitamin deficiencies
What causes SIBO?
There are many different potential causes of SIBO. They include:
- Not having enough stomach acid (for example, if you take a proton pump inhibitor to manage acid reflux)
- Structural abnormalities in the bowel (for example, an obstruction or changes after an intestinal surgery)
- Small intestine motility disorder (i.e., food and waste do not move through the gastrointestinal tract properly)
SIBO is also linked to other health conditions, such as: Crohn’s disease, AIDS, chronic pancreatitis, liver cirrhosis, fibromyalgia, gastroparesis, celiac disease, scleroderma, and Ehlers-Danlos Syndrome.
Breath Testing for SIBO
The most common method of testing for SIBO is to complete a non-invasive breath test that measures the gases produced by the over-growing microorganisms.
To complete the breath test, you will drink a solution of either glucose or lactulose, then measure your breath at different intervals. If the gas levels are above a certain number after a specified interval of time, it suggests an overabundance of microorganisms in the small intestine.
There are several different test kits available. For all tests, you must follow a 24-hour prep diet, plus discontinue certain medications, herbal supplements, and vitamin/mineral supplements before completing the test.
The Aerodiagnostics lactulose SIBO test kit requires a doctor’s order but can be completed in the comfort of your home. The glucose test kit can be purchased by consumers. Aerodiagnostics tests for hydrogen and methane gases.
Trio Smart Breath Test
The Trio Smart Breath Test tests for all three types of gases (hydrogen, methane, and hydrogen sulfide) produced by microorganisms in your gut. The lactulose kit requires a doctor’s order, but you can order your own glucose kit.
The test kit will be mailed to you, and you can complete the test in the comfort of your home and mail it back to the lab. The results of a glucose test will be sent directly to you, or the lactulose results will be sent to your care provider.
You can order a 3-hour Genova SIBO breath test kit without a physician’s order. The Direct Labs test kit tests for hydrogen and methane gases.
What does a breath test detect?
The three gases produced by the gut microbiome are hydrogen, methane, and hydrogen sulfide.
Hydrogen is produced when specific bacteria in the small intestine feed on sugars from your diet. Hydrogen gas is produced as a by-product of sugar consumption. Elevated levels of hydrogen are a sign of SIBO, and is generally more associated with chronic diarrhea.
Methane is produced when microorganisms called archaea feed on hydrogen. Elevated levels of methane are a sign of IMO and are associated with constipation.
Hydrogen sulfide is produced when certain microorganisms feed on hydrogen. Elevated levels of hydrogen sulfide are associated with diarrhea.
Once you know what kind of overgrowth you’re dealing with, you can create a treatment plan with your care provider.
The treatment plan for SIBO and IMO includes four main steps:
- Kill the overgrowing bacteria or archaea with antibiotics or herbal antimicrobials
- Starve with diet
- Sweep with a prokinetic
- Repair/Reintroduce/Replace with gut repair nutrients, a well-balanced diet, and in some cases, probiotics.
Pharmaceutical Treatment for SIBO
Xifaxan (generic rifaximin) is a prescription medication used to treat SIBO and IMO.
For SIBO treatment: 550 milligrams of Xifaxan three times per day for 14 days. In some cases, a second course of Xifaxan will be given immediately following the first round of treatment.
For IMO treatment: 550 milligrams of Xifaxan three times per day PLUS 500 mg neomycin twice per day for 10-14 days. A combination of Xifaxan and neomycin is most effective in treating IBS patients with elevated methane on a lactulose breath test. (Some practitioners use Metronidazole instead of Neomycin for the second antibiotic.)
Treating SIBO Naturally
If you’re interested in treating SIBO naturally, antimicrobial herbal supplements may also be used. Two commonly used treatments for treating SIBO naturally are:
- Candibactin-BR and Candibactin-AR
- FC Cidal and Dysbiocide
In one study, the above two regimens were equivalent to Xifaxan for the treatment of SIBO and IMO.
There are also other herbal preparations used in the treatment of SIBO and IMO. They include:
- Oil of Oregano
- Bismuth subsalicylate
The herbal preparations used will depend on whether you have SIBO or IMO. It’s best to work with a healthcare provider who is well-versed in SIBO treatment to ensure you’re taking an herbal preparation that will be effective for your specific type of overgrowth.
SIBO and the Migrating Motor Complex
The migrating motor complex is a special cycle of electromechanical activity observed in gastrointestinal smooth muscle between meals. This wave of muscle contractions sweeps away residual undigested material and bacteria from the stomach through the small intestine and into the colon.
When you’re in a fasting state (i.e., you haven’t eaten anything in a while), these muscle contractions occur approximately every 90 minutes, maybe less often in those with constipation.
To promote the migrating motor complex, it’s recommended to space meals about three to five hours apart. This is because if you eat more frequently than that, you don’t ever reach the fasting state that allows the migrating motor complex to sweep through your digestive tract. If the migrating motor complex is not able to sweep debris and bacteria from your digestive tract, they can accumulate and could worsen bacterial overgrowth.
Prokinetics for SIBO
A class of medications and supplements called prokinetics can be used to promote the migrating motor complex. According to research, taking a prokinetic may delay symptom recurrence in SIBO. Since symptom recurrence is common in SIBO, this is an important part of the treatment plan.
There are both prescription prokinetics and over-the-counter prokinetics available. It’s best to work with your healthcare provider to determine which option is best for you.
SIBO and Biofilm Disruptors
Biofilms are a matrix of sticky film that bacteria and fungi use to coat and protect themselves. They can make antibiotic or antimicrobial treatment less effective, so disrupting the biofilms provides a better chance for SIBO die-off.
Biofilm disruptors are often used in people who have SIBO or IMO that is resistant to treatment, or for people who have likely had SIBO or IMO for many years.
The main goal of SIBO treatment is to treat the underlying disease or condition to eradicate bacterial overgrowth. While some studies have looked at the effects of diet in the treatment of SIBO, most of those studies were low quality, making it difficult to apply the results in clinical practice.
A review published in 2022 investigated the effects of the low FODMAP diet, probiotics, fiber supplementation and mindful eating on the gut microbiome in people with IBS. They found that probiotics, fiber, and mindful eating all benefited the gut microbiome. However, most of the studies they looked at did not include SIBO patients, so the potential for diet to influence SIBO is largely hypothetical at this point.
Given many people with IBS also have SIBO, it makes sense to use the low FODMAP diet (download free handout) strategically during SIBO treatment. FODMAPs are types of carbohydrates that are fermented by your gut bacteria. The low FODMAP diet has been shown to improve symptoms of IBS.
It is generally recommended to eat some high-FODMAP foods during antibiotic treatment to ensure that the bacteria are metabolically active and therefore susceptible to the antibiotics. It’s also recommended to eliminate FODMAPs for four to six weeks following antibiotic/antimicrobial treatment to ensure that any remaining bacteria do not have anything to “feed” on.
Preventing the Recurrence of SIBO
Unfortunately, SIBO and IMO recur in approximately two-thirds of patients. The key to avoiding recurrence is focusing on the underlying cause of the overgrowth to delay recurrence.
Since inadequate stomach acid may be one of the causes of SIBO/IMO, weaning off proton pump inhibitors (medications used to treat heartburn, such as Nexium and Prilosec) may be beneficial in preventing recurrence.
It’s best to work with a healthcare provider as you wean off proton pump inhibitors, as stopping them abruptly can lead to rebound acid production and a worsening of heartburn symptoms.
Migrating Motor Complex
Disruptions to the migrating motor complex, such as in people who have had abdominal surgery and have scar tissue, may also lead to the recurrence of SIBO and IMO.
If it is suspected that scar tissue is disrupting the migrating motor complex, abdominal massage and visceral mobilization may be considered. More information can be found at clearpassage.com or barralinstitute.com.
Pelvic Floor Disorders
For people with constipation, it may also be beneficial to be evaluated for pelvic floor dyssynergia. This condition causes uncoordinated contractions of the pelvic floor muscles, which may make it difficult to have a bowel movement. If these muscles are not able to promote a bowel movement, waste and bacteria may become stuck in the digestive tract, leading to overgrowth. Consider meeting with a pelvic floor provider.
When you’re stressed, your body is stuck in “fight or flight” mode. This shifts the focus away from digestion. The goal is to shift your body back into “rest and digest” mode so that digestion will be prioritized by the body. Some effective stress management techniques include:
- Gut-directed hypnotherapy, such as the Nerva or Regulora app
- Cognitive behavioral therapy (CBT), such as the Zemedy or Mahana app
We need gut bacteria to live, but when too many bacteria and other microorganisms colonize our small intestine, unpleasant gut symptoms arise. Once you’ve completed a breath test to determine what kind of overgrowth you’re dealing with, you can move on to treating SIBO. While there isn’t enough evidence to support the use of dietary interventions to treat SIBO (yet!), antibiotics and antimicrobials have been shown to be effective treatments.