What is SIBO?
Small intestinal bacterial overgrowth (SIBO) occurs when gut bacteria become too plentiful in the small intestine leading to symptoms of gas, bloating, diarrhea or constipation.
In a healthy gut there are huge numbers of bacteria in the large intestine (which is also called the colon) and relatively small numbers of bacteria in the small intestine. In the colon these “probiotic” bacteria feed on the indigestible components of our food (prebiotics aka fibre) where they ferment it to produce compounds that are beneficial to our health (like the anti-inflammatory short chain fatty acid called butyrate).
The small intestine is a 20 foot long tube between your stomach and colon. This is where food is broken down so that you can absorb its nutrients through the wall of the small intestine. If bacteria become too plentiful here they are given access to an all you can eat buffet – served three times per day. The result is a large amount of fermentation due to the abundance of carbohydrates that are still intact in your small intestine. And fermentation forms gas. Lots of gas!
SIBO typically occurs due to an underlying dysfunction of intestinal motility (translation: movement). Under normal circumstances, the small intestine contracts and relaxes in an organized manner, constantly moving undigested food particles and gut bacteria downstream to the colon (this is called peristalsis, in case anyone quizzes you). When normal intestinal motility becomes compromised, bacteria are permitted to grow to excessive numbers in the wrong segment of the gut.
In a person with SIBO the resulting build up of gas and bacterial toxins causes digestive symptoms while also perpetuating the condition by causing ongoing damage to intestinal motility. It’s a vicious cycle! Normal digestion and nutrient absorption can become severely compromised and body systems outside the gut may be affected (i.e. brain, skin, thyroid, joints)
Signs and Symptoms of SIBO:
- Bloating and distention
- Flatus (farting)
- Belching (burping)
- Feeling full quickly
- Heartburn/acid reflux
- Iron deficiency
- Vitamin B12 deficiency
- Tingling in arms and legs
- Anxiety and/or depression
- Joint and muscle pain
- Brain fog
- Poor concentration
- Memory problems
- Weight loss/weight gain
- Autoimmune disease
Risk Factors for SIBO:
- proton pump inhibitors (drugs for heartburn/GERD treatment)
- opioid drugs
- anticholinergic drugs
- gall bladder removal
- pancreatic insufficiency
- previous abdominal surgery
- GERD, heartburn or acid reflux
- irritable bowel syndrome or IBS
- inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
- celiac disease
- traumatic brain injury or concussion
- any episode of gastroenteritis (food poisoning) even if long ago
- chronic stress or anxiety
- insomnia or sleep deprivation
How is SIBO diagnosed?
Currently the best lab test for diagnosing SIBO is a non-invasive breath test that measures abnormal gasses in your breath following the ingestion of lactulose sugar. Performed at home, the 3 hour lactulose breath test requires that you follow a special diet for one day only and then fast overnight before performing the test the following morning. On the morning of the test you collect a baseline breath sample, then you ingest a lactulose sugar solution and proceed to collect a series of 9 additional breath samples every 20 minutes. The process takes 3 hours. These samples are analyzed by the lab to detect unusual elevations in hydrogen and methane gas which will be present in high levels if you have SIBO.
Treating people with SIBO has become a special interest in my integrative medicine practice where I focus on the connection between gut health and chronic disease. Here are some frequently asked questions about small intestinal bacterial overgrowth:
Q: My physician or gastroenterologist has run imaging and other tests and said there is nothing wrong with me. Is it possible that I have SIBO?
A: You cannot see SIBO with diagnostic imaging like an ultrasound, x-ray, CT scan, MRI, endoscopy or colonoscopy. Current small intestinal culture techniques are invasive, expensive and not satisfactory for the diagnosis of SIBO. Physicians in Ontario rarely run lactulose breath tests and this means that a typical workup by a family doctor or gastroenterologist does not rule out SIBO. It is a commonly missed diagnosis affecting a lot of people with gastrointestinal symptoms, particularly those who have a diagnosis of IBS.
Q: My physician or gastroenterologist told me I have IBS. Could I have SIBO?
A: Studies show that a significant percentage of people with a diagnosis of irritable bowel syndrome (IBS) actually have underlying SIBO and that their IBS symptoms improve or disappear when SIBO is successfully eradicated. If you have IBS and are not responding to the standard medical treatment you should consider being tested for SIBO.
Q: Is there a cure for SIBO?
A: Studies have shown that a large percentage of people with SIBO experience a resolution of their digestive symptoms (bloating, gas, irregular bowel habits) and systemic symptoms (rosacea) when SIBO is successfully eradicated. As with many chronic, complex conditions, we cannot guarantee that a particular treatment will lead to a complete resolution of all symptoms and effectively “cure” the condition entirely or indefinitely. SIBO treatment can take months and there is rarely a quick fix. SIBO also has a high recurrence rate. Successful care plans should include support for optimizing digestive function and modifying underlying risk factors in order to reduce the risk of recurrence. It is important to work with an experienced integrative medicine practitioner to obtain a correct diagnosis and evidence-based treatment options for SIBO.
Q: What does SIBO treatment look like?
A: Studies show that certain antibiotics and certain antimicrobial herbs are effective in eradicating SIBO. The condition is considered to be eradicated when a repeat breath test shows that previously elevated gas levels have normalized, which is typically accompanied by a resolution of symptoms. Studies have shown that certain combinations of botanicals or herbs work just as well as the best antibiotic drug currently available to treat SIBO. In addition to killing bacteria in the small intestine it is important to treat gut motility at the same time; this can be accomplished with certain botanicals, nutraceuticals or drugs known as pro-kinetics. In more severe cases, short term dietary changes and medical foods are helpful to reduce symptoms and accelerate response to treatment, such as the Low FODMAP Diet and Elemental Diet.
Q: Can you treat me for SIBO without performing the breath test?
A: It is important to have the SIBO breath test performed to confirm your diagnosis before beginning treatment. Other conditions requiring different treatments can mimic SIBO. Jumping into SIBO treatment based on symptoms alone could be ineffective, a waste of your resources, and potentially dangerous if something even more serious has been missed. Additionally, because the breath test quantifies gas levels I find it invaluable for gauging the duration of treatment that may be required. High levels of gas are thought to correlate with a higher numbers of bacteria. While some people with SIBO improve within a couple months of treatment, others require treatment spanning several months. It’s important that you and your SIBO doctor know what to expect and how to individualize your treatment.
Q: I thought I had a food sensitivity, intolerance or allergy. I thought it was gluten. Could I have SIBO?
Foods containing high levels of fermentable carbohydrates tend to exacerbate symptoms of SIBO. These include but are not limited to dairy, wheat and other gluten containing grains, onions, garlic, some fruits, vegetables and even nuts and sweeteners. People with SIBO can be misdiagnosed by a naturopath or other doctor with a food sensitivity, “food allergy” or gluten or dairy intolerance leading them to follow a restrictive diet, thinking they need to follow it for life. For example, many non-celiacs with SIBO feel a lot better on a gluten free diet; however, their symptoms may not be related to gluten but rather to the fermentation of fructans in the gluten containing grains by their rogue gut bacteria. The same thing can happen with dairy – if the bacteria get to it first, they can ferment it before your enzymes have a chance. Enter gas, bloating, diarrhea, nutrient deficiencies, brain fog, joint pain and skin rashes – it’s not hard for one to blame gluten or dairy, which can also cause these symptoms in some people. When you clear out small intestinal bacterial overgrowth, heal the gut lining and get gut motility back on track, some of these individuals may be able to tolerate gluten containing grains and a bit of dairy after all. And that’s a good thing given that gluten containing grains can be healthy for non-celiacs, promoting the growth of beneficial gut bacteria, and fermented dairy is an excellent source of protein and calcium, not to mention gut friendly in people without a true dairy allergy. Does this all sound complicated? It is. That’s why you should trust a skilled integrative medicine practitioner with an evidence based approach to help you sort out your gut woes.
Q: What is a FODMAP?
A: FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These are carbohydrates that can be fermented by gut bacteria. They are found in many foods, both healthy and unhealthy. People with SIBO are generally made a lot worse by eating them, especially in large servings which lead to more gas and bloating, diarrhea, or constipation. When SIBO is eradicated people can often tolerate FODMAPs again.
Q: Do I have to change my diet? What is the best diet treatment for SIBO?
The Low FODMAP Diet, Specific Carbohydrate Diet and Elemental Diet are often recommended to treat SIBO. These diets reduce or completely eliminate fermentable carbohydrates for a period of time in order to starve gut bacteria. While the Low FODMAP Diet and Specific Carbohydrate Diet may reduce symptoms, research has not shown them to be curative on their own (as of yet). There is some research to support the efficacy of the elemental diet in inducing remission, although this approach is incredibly restrictive and needs to be supervised by a qualified practitioner. SIBO diets may help with symptom management and could in theory accelerate response to treatment, but but they do not address the underlying motility dysfunction and patient risk factors that led to SIBO in the first place. Additionally, many foods restricted by these diets are needed in the diet to maintain the health of bacteria in the colon; restricting these foods for too long may cause more harm than good to the microbiome, your stress level and your social life! When I do recommend dietary changes for SIBO it is only for a few weeks to help induce remission, it is only as restrictive as it truly needs to be, and it is always done in conjunction with a comprehensive care plan targeting the underlying causes of SIBO.