SIBO stands for small intestinal bacterial overgrowth. It means there are excessive bacteria in the small intestine, where they can interfere with normal digestion and absorption.
Symptoms may include bloating, wind, abdominal discomfort, diarrhoea or unpredictable digestion. Some people also have constipation, particularly where methane production is involved.
If you have been told you have SIBO, it can be tempting to ask, “What do I take to get rid of it?” A useful further question is: “Why has my digestion become so compromised?”
More than a question of excess bacteria
Bacteria can ferment food before it has been fully digested and absorbed, producing gas and other byproducts.
Some bacteria also carry lipopolysaccharide, or LPS, in their outer membrane. LPS is a bacterial component that can activate the immune system; it is not a gas or simply a product of fermentation.
Where intestinal barrier function is impaired, greater exposure to bacterial components may contribute to inflammation. Substances absorbed from the intestine travel towards the liver through the portal circulation, connecting gut health with liver processing and immune activity.
This is why I consider microbial balance, digestion, movement through the intestine and liver health together.
Bile, the liver and SIBO
Your liver makes bile, which helps disperse dietary fats so digestive enzymes can work on them. It also supports the absorption of fat soluble vitamins A, D, E and K.
Bile acids contribute to the small intestine’s antimicrobial defences. They help shape the environment in which microbes grow.
Insufficient bile delivery can weaken this defence and impair fat digestion. Bacterial overgrowth can also change bile acids, reducing their effectiveness and contributing to fat malabsorption.
This creates a relationship that can work in both directions: altered bile function can favour microbial imbalance, while microbial activity can interfere with normal bile acid function.
Poorly digested food and altered microbial metabolism can contribute to further symptoms. Inflammation and bacterial byproducts may also affect the gut barrier. These processes are related, but undigested fat alone does not establish that the barrier is damaged.
Why movement through the gut matters
Motility means the coordinated movement that carries food and digestive contents onwards.
Between meals, the small intestine has a pattern of clearing contractions called the migrating motor complex, or MMC. It is sometimes described as the gut’s housekeeping system.
When clearance is disrupted, bacteria and food residues can remain in the small intestine for longer, encouraging fermentation and making overgrowth more likely to persist or return.
Previous infection, surgery, medicines, underlying digestive conditions and other health factors may affect this movement. Stress, sleep and daily routines also belong in the wider assessment.
Bowel movements are a priority
If you are constipated, getting the bowels moving comfortably and regularly is an important part of the plan.
I consider stool frequency and consistency, straining, incomplete emptying, fluids, food intake, movement and any underlying reasons for constipation.
A daily bowel movement does not prove that small intestinal motility is normal. Equally, bowel frequency alone does not diagnose SIBO. Both bowel habits and movement higher in the digestive tract need consideration.
The aim is to avoid repeatedly treating microbial overgrowth while leaving persistent constipation or impaired clearance unaddressed.
Hydrogen, methane and hydrogen sulphide
Different organisms produce or use different gases, so the pattern can help guide assessment.
Hydrogen is produced during bacterial fermentation and can be measured on suitable breath tests.
Methane is produced by organisms called archaea, rather than bacteria. Excess methane is often associated with constipation and is described as intestinal methanogen overgrowth, or IMO. It can occur beyond the small intestine too.
Hydrogen sulphide, sometimes written H2S, is produced through certain microbial pathways and also has normal signalling roles in the body.
The concern is an excessive local burden or an imbalance in production and handling, rather than the presence of hydrogen sulphide itself.
Hydrogen sulphide and sulphur reactions
Some people describe rotten egg smelling gas, bloating or discomfort after foods such as eggs, garlic, onions or certain vegetables.
Others report difficulty tolerating supplements containing sulphur, including NAC, glutathione, MSM, alpha lipoic acid or taurine.
These experiences deserve attention, particularly when several products marketed for liver support make someone feel worse. However, they do not confirm hydrogen sulphide overgrowth or mean that all sulphur containing foods are unsuitable. For example, onions and garlic also contain fermentable carbohydrates that can cause symptoms for other reasons.
Microbes such as Desulfovibrio and Bilophila can participate in hydrogen sulphide production. Stool findings may help explore the wider microbial picture, but they cannot establish where overgrowth is occurring or directly measure small intestinal gas production.
Where appropriate and available, a breath test that measures hydrogen sulphide may provide additional information. Standard hydrogen and methane tests do not measure it.
Supporting digestion before adding more products
My approach is to stabilise and support before introducing an intensive antimicrobial or detoxification programme, particularly if you are highly reactive or already eating a very restricted diet.
This can involve improving nutritional intake, addressing constipation, reviewing meal tolerance and considering stomach, bile and pancreatic function.
Sodium, potassium, chloride and zinc contribute to normal physiology, including processes around digestion. That does not mean that everyone needs extra mineral salts or stomach acid supplements.
Betaine HCl may be considered only after assessment. It can aggravate gastritis, ulcers or an inflamed stomach and is not a routine SIBO treatment.
Where targeted supplements may fit
The products below are examples for discussion, not recommendations to start them. Every individual needs assessment and a guided approach.
Immunoglobulin products such as MegaIgG
These contain animal derived immune proteins and are discussed for their ability to bind certain microbial components, including LPS, within the intestine. This is different from proving that a product removes a SIBO infection or clears toxins throughout the body.
Zinc carnosine
Zinc carnosine may be considered for mucosal support. The preparation, total zinc intake, duration and individual circumstances matter.
Vitamin K2 in the MK4 form
Vitamin K2, MK4, is sometimes discussed in relation to tissue support. Evidence that supplementation directly restores the intestinal lining in SIBO is limited, so it is not presented as an established barrier repair treatment. Suitability also depends on medicines, particularly vitamin K antagonist anticoagulants.
Bile and digestive support
Bitter preparations, selected enzymes or bile support may be considered when indicated. Additional bile is not suitable for everyone and may worsen bile acid diarrhoea.
For someone reporting sulphur reactions, I review tolerability before adding products such as taurine or NAC. Temporary dietary adjustments should remain targeted and nutritionally adequate, rather than become a permanent list of forbidden foods.
When antimicrobial treatment may be considered
Once initial support is underway and you are tolerating the plan, targeted treatment may be appropriate alongside continued work on digestion and motility.
This may involve prescribed treatment or selected herbal antimicrobials, according to the findings and individual circumstances. Supportive preparation should not delay necessary medical care, and there is no requirement to prove that the barrier is fully repaired before treating confirmed overgrowth.
The aim is to address the microbial problem while also improving the conditions that allowed it to develop.
My approach
I bring together your symptoms, bowel habits, food reactions, previous infections, medicines, surgical history and existing results.
Where appropriate, I may recommend breath testing, relevant blood markers or comprehensive stool analysis. Each answers different questions, and a stool test cannot diagnose SIBO on its own.
Your plan may include making meals more comfortable, supporting regular elimination, reviewing nutritional needs and introducing targeted products gradually.
The aim is better digestion, broader food tolerance and a plan that addresses the reasons symptoms persist or return.
When to seek further assessment
Please seek medical assessment for unexplained weight loss, blood in your stool, persistent vomiting, significant pain, ongoing diarrhoea or signs that you may not be absorbing enough nourishment. A SIBO label should not prevent other causes of symptoms from being investigated.
If you feel you need support in this area, please reach out and let’s take the next steps together towards improving your overall wellbeing.
Lisa Cahill
Qualified nurse and naturopathic nutritionist
Evolve Female Wellness
lisa@evolvefemalewellness.com
All supplements and herbal preparations mentioned are included as an educational guide only. They are not recommendations to take them and do not suit everybody. Every individual needs a guided approach based on their symptoms, test results, medical history, medicines and tolerance. Please seek individual assessment before starting or combining products.