What Is SIBO? A Naturopathic Overview of Small Intestinal Bacterial Overgrowth

SIBO is one of the most poorly understood digestive conditions I see as a naturopath. Small Intestinal Bacterial Overgrowth affects many people who struggle with ongoing digestive discomfort, often for years, without clear answers. Research shows that SIBO is found in anywhere from 4 to 78 percent of people diagnosed with irritable bowel syndrome, while rates in people without digestive symptoms range between 1 and 40 percent.

Many people living with SIBO experience bloating, nausea, diarrhoea, constipation, and signs of poor nutrient absorption. In clinical practice, I see how significantly SIBO can affect quality of life. Over time, bacterial overgrowth in the small intestine can interfere with digestion and nutrient absorption, contributing to fatigue, low mood, bone loss, and nervous system symptoms.

This article is the first in a series designed to explain SIBO in a clear, grounded way from a naturopathic perspective. Here, we lay the foundation. Later articles will explore symptoms, causes, testing, and supportive strategies in more detail.

What Is SIBO? A Simple Explanation

Q. What is SIBO?

A. SIBO (Small Intestinal Bacterial Overgrowth) is a digestive condition where excessive bacteria grow in the small intestine instead of remaining mostly in the large intestine. This bacterial overgrowth can interfere with digestion, nutrient absorption, and normal gut function.

SIBO stands for Small Intestinal Bacterial Overgrowth. At its core, it describes a situation where bacteria that normally belong in the large intestine are present in excessive numbers in the small intestine. In simple terms, it is too much bacteria in the wrong place.

The small intestine is designed to have relatively few bacteria compared with the colon. In healthy digestion, bacterial levels in the small intestine remain low enough to allow food to be broken down and absorbed efficiently. When these levels rise, normal digestion is disrupted.

Several protective systems help prevent bacterial overgrowth, including stomach acid, digestive enzymes, bile, and healthy intestinal movement. Between meals, a specialised cleansing pattern of movement called the migrating motor complex helps sweep residual food and bacteria down into the large intestine.

When these protective mechanisms are weakened, bacteria can begin to accumulate in the small intestine. These bacteria ferment food too early in the digestive process and produce gas and other byproducts. They may also interfere with bile salts needed for fat digestion and compete with the body for nutrients such as vitamin B12.

Over time, this can contribute to poor fat absorption, deficiencies in fat-soluble vitamins, and reduced absorption of minerals like calcium.

​SIBO is often categorised by the types of gas produced by bacteria. Hydrogen and hydrogen sulfide are more commonly associated with loose stools, while methane production is often linked with constipation. These patterns help explain why SIBO symptoms vary so widely from person to person.

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SIBO is frequently confused with IBS because symptoms overlap significantly. However, they are not the same condition. You can have SIBO without IBS, and many researchers believe that bacterial overgrowth may drive symptoms in a large portion of people labelled with IBS.

From a naturopathic perspective, SIBO is not just an infection to eliminate. It is a sign that the digestive system’s normal balance and movement have been disrupted. Understanding why that has occurred is key.

How the Small Intestine Supports Digestion

To understand SIBO, it helps to understand how the small intestine normally works. The small intestine is an extraordinary organ, measuring around six metres in length. Its main role is to digest food and absorb nutrients.

Unlike the large intestine, which is home to trillions of bacteria, the small intestine is meant to contain relatively few microbes. This low-bacteria environment allows digestive enzymes and bile to break down food efficiently without bacterial interference.

Several factors help keep bacterial numbers low in the small intestine. Stomach acid limits bacterial survival, digestive enzymes and bile create an unfavourable environment, and rhythmic muscular contractions keep food moving forward so it does not stagnate.

Food enters the small intestine from the stomach and passes through three sections: the duodenum, jejunum, and ileum. As it moves along, it is mixed with digestive juices and broken down into small molecules that can be absorbed.

The inner lining of the small intestine is highly specialised for absorption. Millions of tiny finger-like projections dramatically increase its surface area, allowing nutrients, vitamins, minerals, and water to pass efficiently into the bloodstream.
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More than 90 percent of nutrient absorption occurs here. When bacteria interfere with this process, the effects can be felt far beyond the gut.

What Happens in SIBO?

Common SIBO Symptoms

SIBO commonly causes bloating, abdominal distension, excess gas, diarrhoea, constipation, or alternating bowel habits. Many people also experience fatigue, brain fog, nausea, nutrient deficiencies, and symptoms outside the gut such as joint pain, skin issues, or low mood.

When bacteria begin to overgrow in the small intestine, several changes occur that help explain common symptoms.

The first problem is early fermentation. Bacteria begin breaking down carbohydrates before the body has had a chance to digest and absorb them properly. This produces gas in a part of the intestine that is not well equipped to handle it.

As gas builds up, people may experience bloating, pressure, visible abdominal distension, and discomfort that often worsens after meals. Unlike ordinary bloating, this distension can be significant and persistent.

Different bacteria produce different gases. Hydrogen and hydrogen sulfide gases are often associated with loose stools, while methane production tends to slow intestinal movement and contribute to constipation. Many people experience a mix of symptoms.

SIBO also affects nutrient absorption. Bacteria can disrupt bile salts needed to digest fats, leading to fatty stools and deficiencies in fat-soluble vitamins. They can damage the intestinal lining and compete for key nutrients, including vitamin B12.

Over time, these deficiencies may lead to fatigue, weakness, numbness or tingling, bone loss, and neurological symptoms. 

SIBO does not only affect digestion. Increased intestinal permeability may allow bacterial toxins to enter the bloodstream, triggering widespread inflammation. This can contribute to symptoms such as brain fog, joint pain, skin issues, and changes in mood.
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From a whole-body perspective, SIBO is not just a gut condition. It is a systemic issue that reflects broader dysfunction within the digestive and nervous systems.

Why SIBO Is Often Missed or Misunderstood

Despite growing research, SIBO is frequently overlooked. One reason is its strong overlap with IBS. Bloating, abdominal pain, and altered bowel habits occur in both conditions, and IBS has historically been used as a diagnosis when no clear cause is found.

Testing for SIBO also has limitations. The most definitive test involves sampling fluid from the small intestine during an endoscopy, but this is invasive, expensive, and not widely used. Breath testing is more accessible but imperfect, with accuracy influenced by gut transit time, diet, and recent medication use.

As a result, many people are treated for symptoms rather than underlying causes. Medications may help manage discomfort but often do not address why bacterial overgrowth developed in the first place.
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This is one area where naturopathic medicine takes a different approach. Rather than viewing SIBO as random, we look for contributing factors that disrupt normal digestion and motility, such as infections, medications, stress, hormonal influences, and structural changes in the gut.

Q. Is SIBO the same as IBS?

A. SIBO and IBS are not the same condition, although their symptoms often overlap. IBS is a symptom-based diagnosis, while SIBO refers to a specific bacterial imbalance in the small intestine. Research suggests SIBO may be an underlying driver of symptoms in many people diagnosed with IBS

A Naturopathic View of SIBO

From a naturopathic perspective, SIBO represents a functional imbalance rather than a simple bacterial infection. Bacteria tend to thrive in environments that allow their growth. The key question is why that environment developed.

Healthy digestion depends on adequate stomach acid, digestive enzyme production, bile flow, and coordinated intestinal movement. Disruption in any of these areas can create conditions that allow bacteria to accumulate.

Gut motility plays a particularly important role. Between meals, the migrating motor complex helps clear residual food and bacteria from the small intestine. Stress, illness, and nervous system dysregulation can impair this process.

The nervous system has a direct influence on digestion. Chronic stress can slow gut movement, reduce stomach acid, and weaken immune defences in the gut. Over time, this can contribute to bacterial imbalance.

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​A naturopathic approach looks beyond the bacteria themselves to the systems that regulate digestion, including nervous system function, stress load, nutritional status, and overall health. Targeting bacteria alone without addressing these factors often leads to recurrence.

How Naturopaths View SIBO

From a naturopathic perspective, SIBO is not just an infection to eliminate but a sign that digestion, gut motility, and nervous system regulation are out of balance. Addressing these underlying factors is essential for long-term improvement and reducing recurrence.

Who Commonly Develops SIBO?

SIBO tends to appear in predictable patterns rather than randomly. Many people develop symptoms after a gastrointestinal infection, food poisoning, or prolonged illness. Others notice digestive changes after antibiotic use, which can alter gut microbial balance.

Chronic stress is another common factor. Stress affects digestion through hormonal and nervous system pathways, slowing gut movement and reducing protective digestive secretions.

SIBO also appears more often alongside other digestive conditions, including IBS, inflammatory bowel disease, and conditions that affect gut motility such as diabetes or thyroid disorders. Certain medications, particularly proton pump inhibitors, are associated with increased SIBO risk.

Surgical changes to the digestive tract, especially procedures that alter intestinal anatomy, can also create conditions that favour bacterial overgrowth.
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Recognising these patterns helps explain why SIBO often persists until underlying contributors are addressed.

Conclusion

SIBO is more than excess bacteria in the small intestine. It reflects a disruption in digestion, movement, and regulation that can affect the entire body. Understanding this broader picture helps explain why symptoms are often persistent and why quick fixes do not always work.

Rather than viewing SIBO as something to eliminate, a naturopathic perspective asks why the digestive environment allowed bacterial overgrowth to develop. When we address digestion, motility, nervous system balance, and individual risk factors together, long-term outcomes improve.

Related Articles:
2. SIBO Symptoms

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​​​​Vanessa Winter
​Naturopath & Medical Herbalist
BHSc (Deans Award for Academic Excellence), BED, Adv.Dip.Nat., Adv.Dip.Herb.Med., NMHNZ
​Registered with Naturopaths and Medical Herbalists of NZ (NMHNZ)

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