Small Intestinal Bacterial Overgrowth (SIBO): symptoms, root causes, and how to restore gut balance
Digestive symptoms rarely appear out of nowhere. Yet with SIBO, it often feels exactly like that. One period your digestion feels relatively stable, and the next you are dealing with persistent bloating, abdominal discomfort, changes in bowel movements (constipation or diarrhea), food sensitivities, common SIBO symptoms such as these, and a constant feeling that something in your gut is off. These are all common SIBO symptoms that can significantly impact your gut health.
Many people are told they have Small Intestinal Bacterial Overgrowth (SIBO), and it is also increasingly recognised as a common underlying factor in chronic digestive symptoms such as IBS (Irritable Bowel Syndrome). However, what this diagnosis often does not explain is why this imbalance developed in the first place. Because SIBO is not just a bacterial overgrowth. It is a signal. A signal that something in your digestive rhythm, microbiome balance, motility, or nervous system is out of balance.
In my work as a holistic dietitian, I often see SIBO not as an isolated condition, but as part of a wider pattern involving the gut microbiome, stress physiology, and digestive function.
In this article, you will discover what SIBO actually is, its root causes, why it often keeps coming back, and how you can start supporting your gut in a more root-cause-focused and holistic way to restore gut balance.
What is SIBO? Understanding Small Intestinal Bacterial Overgrowth
Small Intestinal Bacterial Overgrowth (SIBO) refers to a condition where microorganisms that normally belong in the large intestine migrate or overgrow in the small intestine. Understanding this mechanism is essential for effective Small Intestinal Bacterial Overgrowth treatment, as it determines the approach needed to restore balance.
In a healthy digestive system, the small intestine contains relatively low amounts of bacteria. Its primary role is nutrient absorption, not fermentation. When bacteria accumulate in this part of the gut, they begin fermenting food too early in the digestive process, producing gas and triggering symptoms.
This can lead to:
Excess gas production
Bloating (often shortly after meals)
Abdominal discomfort or pressure
Changes in bowel movements
Food intolerances
Fatigue or brain fog in some cases
But what is often overlooked is that SIBO is not the root problem itself. It is usually the result of an underlying dysfunction in the gut environment.
SIBO symptoms: common signs, what your body may be communicating
SIBO symptoms can vary widely between individuals, which is why it is often misunderstood or misdiagnosed.
Common digestive SIBO symptoms
The most common symptoms include:
Bloating, especially after eating
Excess gas or burping
Abdominal distension
Constipation, diarrhea, or alternating bowel patterns
Nausea or early fullness
Non-digestive SIBO symptoms
What I often see in practice is that SIBO rarely affects only digestion.
It can also be linked to:
Skin issues such as acne, eczema or rosacea
Fatigue or low energy
Brain fog or difficulty concentrating
Hormonal symptoms such as PMS or cycle irregularities
Food sensitivities and histamine reactions
These symptoms reflect the broader role of the gut microbiome in inflammation, nutrient absorption, and immune regulation.
What causes SIBO? Root causes of small intestinal bacterial overgrowth
SIBO is rarely caused by one single factor. Instead, it is usually the result of multiple systems becoming dysregulated over time.
Below are the most common root patterns I see in practice.
1. Impaired gut motility and SIBO: the role of the migrating motor complex (MMC)
One of the most important mechanisms in preventing SIBO is gut motility, particularly the migrating motor complex (MMC). This is one of the key root causes of SIBO which is often overlooked. MMC is a natural cleansing wave in the small intestine that helps move food and bacteria downward. MMC helps prevent bacterial stagnation in the small intestine. When this system slows down, bacteria are more likely to remain and overgrow in the wrong place.
Slow motility can be influenced by:
Chronic stress
Irregular meal patterns
Post-infectious changes
Nervous system dysregulation
2. Gut microbiome imbalance (dysbiosis) and SIBO
SIBO rarely exists on its own. It is often part of a broader gut microbiome imbalance, where microbial diversity is reduced across the digestive system. If you want to explore this further, you can read more about the gut microbiome and its role in IBS, digestive, skin and hormonal symptoms. When beneficial bacteria in the large intestine are reduced, or when opportunistic strains dominate, the ecosystem becomes less stable.
This can lead to:
Altered fermentation patterns
Increased gas production
Reduced colon resilience
A higher likelihood of bacterial migration
From a holistic perspective, SIBO is often a reflection of reduced microbial diversity across the whole gut ecosystem.
3. Low stomach acid and SIBO: how reduced digestive function contributes to bacterial overgrowth
Stomach acid is one of the body’s natural protective mechanisms.
It helps:
Break down food
Sterilise incoming microbes
Support nutrient absorption
When stomach acid is low, bacteria that should be neutralised earlier in digestion can survive and move further into the small intestine.
This can be influenced by:
Chronic stress
Long-term medication use, especially antacids
Nutrient deficiencies
Nervous system imbalance
4. Stress, nervous system dysregulation and SIBO
One of the most underestimated drivers of SIBO is the nervous system.
When the body is in a prolonged stress state, digestion is deprioritised.
This affects:
Gut motility
Enzyme production
Blood flow to the digestive system
Microbiome balance
In practice, I often see that SIBO symptoms intensify during stressful periods, even when diet stays the same. This is not a coincidence, but physiology. This is why a holistic SIBO support approach often includes nervous system regulation, not only dietary changes.
5. Post-infectious SIBO: how gut infections can trigger bacterial overgrowth
In some cases, SIBO develops after a gut infection such as food poisoning or gastroenteritis. After infection, persistent SIBO symptoms may develop when the gut does not fully recover.
This can temporarily disrupt:
Gut motility
Microbial balance
Immune signalling in the gut
For some people, the gut does not fully “reset” after this event, leaving behind an imbalance with persistent symptoms.
Because SIBO can have multiple underlying causes, a personalised approach is often essential. If you would like support in identifying potential root causes and restoring gut balance, you can schedule an intake consultation via the button below. Consultation are available online and worldwide.
Types of SIBO explained: hydrogen, methane (IMO), and hydrogen sulfide SIBO
SIBO is not a single pattern. It is often categorised based on the type of gas produced by bacteria.
Hydrogen-dominant SIBO
Often associated with:
Diarrhea
Rapid transit
Methane-dominant SIBO (IMO)
Methane production is driven by methanogens, which are archaea instead of bacteria.
Often linked to:
Slower motility
Strong bloating and distension
Hydrogen sulfide SIBO
Less commonly discussed, but often associated with:
Sulfur-smelling gas
Sensitivities
Mixed bowel patterns
These patterns are often identified through breath and stool testing, but symptoms can already give important clues.
SIBO testing: breath test, diagnosis and how SIBO is identified
The most common method used to identify SIBO is a breath test measuring hydrogen and methane gases. This test is not perfect, but it can give useful insight into fermentation patterns in the small intestine.
Hydrogen sulfide-related patterns can be captured in a different way, stool testing can provide supportive information about sulfur-reducing bacteria and overall microbial balance.
However, in clinical practice, I always see testing as one part of a bigger picture. Symptoms, lifestyle, microbiome patterns, and history are also important in understanding what is going on.
Why SIBO keeps coming back: causes of recurrence and relapse
One of the most frustrating experiences with SIBO is recurrence. This often happens because when approaches to Small Intestinal Bacterial Overgrowth treatment focus only on short-term symptom relief, without addressing the underlying recurrence drivers.
There are several reasons why SIBO may keep coming back:
This often happens because:
Only symptoms are treated, not root causes
Gut motility is not restored
Nervous system dysregulation remains
Microbiome imbalance is not addressed holistically
Lifestyle patterns continue to disrupt digestion
Without addressing these foundations, SIBO can more easily reappear. Even when symptoms improve, SIBO may not fully resolve if the underlying drivers such as motility, microbiome imbalance, or nervous system regulation are not adequately addressed, and it can therefore persist or recur over time.
Holistic SIBO treatment: restoring gut function, motility and microbiome balance
Instead of focusing only on restriction, I always look at restoring function and balance.
Supporting gut motility and rhythm
Regular meal structure
Avoiding constant snacking
Supporting natural digestive cycles
Supporting the nervous system
Slow breathing before meals
Reducing chronic stress load
Creating space for rest and digestion
Supporting microbiome diversity and gut lining
Fibre diversity (as tolerated), with a Low FODMAP approach often recommended initially.
Polyphenol-rich foods, such as blueberries, green tea, olive oil and herbs like oregano and rosemary
Gut lining support foods such as bone broth, ghee, collagen-rich foods, and omega-3 rich foods (fatty fish, chia- and flax seeds), which may help support intestinal barrier integrity
Gradual food reintroduction instead of long-term restriction
Supporting digestion instead of limiting it
Effective SIBO treatment is not only about removing foods for a certain time, but also about supporting digestion and restoring gut function.
Improving chewing and mindful eating
Supporting stomach acid and enzymes naturally
Avoiding unnecessary long-term dietary restriction
SIBO is not just a bacterial issue: why gut motility, stress and the microbiome matter
What I see most often is that SIBO is not really about bacteria alone.
It is about:
How your gut moves
How your nervous system regulates digestion
How your microbiome ecosystem functions as a whole
How your body responds to stress over time
Which is why a purely restrictive or protocol-based approach often does not lead to long-term resolution.
A holistic approach to SIBO healing and gut restoration
Healing is rarely about eliminating everything. It is about restoring communication within the body.
When the gut, nervous system, and microbiome begin to work together again, symptoms often start to shift naturally. This is also why a personalised approach is so important. Because no two SIBO cases are exactly the same.
Personal and holistic guidance for SIBO (Small Intestinal Bacterial Overgrowth)
SIBO is not just a diagnosis. It is a message from your body. A message that something in your internal ecosystem needs attention and care.
If you recognise yourself in these symptoms, it may be less about finding the perfect diet, and more about understanding your unique root causes and restoring balance.
As a holistic dietitian, I support clients in identifying whether SIBO may be contributing to their symptoms through a personalised and in-depth approach. If you already know you have SIBO, I can help you with a tailored SIBO treatment plan and personal guidance throughout your recovery process. This holistic SIBO support approach focuses on restoring gut motility, reducing gut microbiome imbalance, and addressing underlying root causes of SIBO.
When you have any questions, or if you would like to schedule your intake consultation, you can do so via the button below. Consultations are online and worldwide available.
Looking forward to meeting you!
Love,
Nina