5 Signs That SIBO Might Be the Cause of Your IBS Symptoms

Irritable Bowel Syndrome, or IBS, is a complex condition that affects the large intestine or colon, and can cause a variety of symptoms, including cramping, abdominal pain, bloating, and gas, as well as diarrhea, constipation, or both.

For those suffering from IBS, finding the root cause of these uncomfortable symptoms can feel like navigating a maze with no clear path. However, studies indicate that up to 80% of patients with IBS also have a lesser-known condition, Small Intestinal Bacterial Overgrowth (SIBO), which could be a significant trigger for IBS.

Learn more about the functional medicine approach to digestive health at CentreSpringMD.

What Is SIBO?

Small intestinal bacterial overgrowth occurs when there is an abnormally high number of bacteria in the small intestine. Typically, the small intestine contains a low number of bacteria compared to the large intestine. However, when SIBO occurs, there is an overgrowth of bacteria in the small intestine, leading to various symptoms and complications.

SIBO can happen to anyone, but it is more common in individuals with underlying conditions like IBS, celiac disease, and inflammatory bowel disease (1). Bacterial overgrowth in the small intestine can cause an imbalance in gut flora, leading to inflammation and damage to the intestinal lining.

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Signs That SIBO Might Be the Cause of Your IBS Symptoms

If you have been diagnosed with IBS or are experiencing digestive symptoms that resemble those of IBS, it is essential to consider the possibility that SIBO might be the underlying cause. Here are five signs to look out for:

Sign 1: Bloated Feeling

If you frequently experience a sensation of fullness, bloating, or visible distension after eating, these could be early signs of SIBO.

This happens because the overgrowth of bacteria in your small intestine leads to excessive fermentation of food in the area where digestion and absorption of nutrients should take place in your digestive tract. The presence of these excess bacteria may result in a build-up of gasses such as methane, hydrogen, and sometimes hydrogen sulfide, which can distend the small intestine, leading to the sensation of bloating and fullness.

Read: H. Pylori Affects Half the Population, but Is It Harmful?

Sign 2: Unpredictable Bowel Movements

Unpredictable bowel movements are a hallmark of both irritable bowel syndrome and SIBO. This occurs because the presence of bacteria can interfere with the normal absorptive and digestive processes, leading to a range of diarrheal-like symptoms even without the presence of actual pathogens in the digestive tract that cause illness.

Patients with excess hydrogen sulfide (SIBO-HS) are more likely to experience diarrhea (2). Levels of hydrogen sulfide, as measured by a breath test, correlate with the severity of diarrhea.

Sign 3: Nutritional Deficiencies and Weight Loss

Some individuals diagnosed with IBS notice unexplained weight loss or the development of deficiencies in essential nutrients like iron, vitamin D, or vitamin B12.

SIBO activity in the small intestine can lead to malabsorption of these nutrients, significantly interfering with your body's ability to carry out healthy digestion (3). Over time, this may lead to unintentional weight loss and nutrient deficiencies that manifest as various symptoms, from anemia to a weakened immune system, and overall health decline.


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Sign 4: Chronic Fatigue and Weakness

Aside from gastrointestinal symptoms, chronic fatigue and weakness are common complaints that can accompany IBS, particularly among those who have struggled for a long time with the condition without relief. The continuous interaction between food and bacteria in the small intestine, due to SIBO, can drain your body’s energy reserves as it fights to maintain the delicate balance disrupted by the overgrowth.

Nutrient deficiencies are also a culprit of fatigue. This can result in consistent fatigue and a lack of vitality, even after what seems like sufficient rest.

Related: How to Test Your Gut Function

Sign 5: Frequent Gas and Bloating

While not uncommon to IBS sufferers, gas and bloating that are especially frequent and get markedly worse after consuming probiotic-containing foods or supplements. The overproduction of gasses caused by bacterial fermentation in the small intestine—that usually shouldn’t be there—can lead to intense and stubborn bouts of gas and distension that do not subside easily.

Excess gas production happens after consuming carbohydrates which feed the bacteria in the digestive system. These bacteria then produce hydrogen, which feeds another type of microorganism in the gut, called archaea. These archaea then produce methane, further contributing to a bloating feeling (4).

For more on the link between gut bacteria and chronic digestive problems like IBS and IBD, read this post. 

Getting Bacteria in Check with Your Functional Doctor

Modern lifestyles can make cultivating a healthy microbiome difficult. And what results is too much of, or the wrong type of bacteria in the wrong place. When left unchecked, this state of dysbiosis can lead to SIBO symptoms.

A functional medicine approach to SIBO includes eradicating overgrowth and preventing future recurrence.

Diet, lifestyle, and genetic factors all play a role in maintaining a healthy gut microbiome for IBS patients, and identifying and treating SIBO early is the best way to reverse dysbiosis and restore balance to your gut.

Digestive upset isn’t normal. If your gut is sending you distress signals, don’t wait to contact CentreSpringMD today.

Testing for SIBO

There isn’t one, singular test to diagnose SIBO, but your integrative doctor will most likely do a lactulose breath test or a hydrogen breath test. Breath testing can differentiate between the SIBO subtypes, which guide treatment plans (5). 

SIBO subtypes include:

  • Hydrogen-dominant. Hydrogen-SIBO shares many symptoms with diarrhea-predominant IBS (IBS-D).
  • Methane-dominant. Intestinal Methanogen Overgrowths (IMO), previously called methane-SIBO. IMO most commonly causes constipation-predominant IBS symptoms (IBS-C).
  • Hydrogen-sulfide-dominant. Patients with excess hydrogen sulfide (SIBO-HS) are more likely to experience diarrhea.

Breath tests look for the gasses that are produced by the bacteria in your small intestine. If you have SIBO, higher levels of these gasses will be present in your breath.

Other common tests used to determine effective SIBO treatment include blood tests and stool samples, which can indicate nutritional deficiencies or abnormal gut flora. Your doctor may also recommend imaging studies, such as an abdominal ultrasound to assess the structure and function of your small intestine.

Treating SIBO with Functional Medicine

Treatment for SIBO typically involves a course of antibiotics to reduce the population of bacteria in the small intestine, supported by dietary changes and lifestyle modifications designed to prevent recurrence. Your functional medicine provider will work with you to create a treatment plan tailored to your specific needs.

Dietary changes, such as eliminating trigger foods and following a low FODMAP diet, as well as using antimicrobial herbs or antibiotics to reduce and rebalance the bacterial overgrowth in your small intestine are common.

Your doctor may also recommend supplements, such as probiotics and digestive enzymes, to support healthy gut function and promote the growth of beneficial bacteria.

How do you begin treating SIBO? Contact your functional provider.

The Key Takeaway

If you identify with several of the above signs, it may be worth discussing the possibility of SIBO with your integrative healthcare provider. Remember, finding the true cause of your IBS symptoms can take time, but being informed about conditions like SIBO can guide you towards the most effective treatment and relief.


gut health, Holistic Medicine

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