Introduction
If you work with or live with endometriosis, you’ve probably noticed that bloating, constipation and gut discomfort often sit alongside pelvic pain. This is not a coincidence. One of the most common drivers behind these symptoms is small intestinal bacterial overgrowth, also known as SIBO.
Understanding the connection between SIBO and endometriosis can completely change how we approach treatment.
What are SIBO and SIMO
SIBO occurs when bacteria that should predominantly live in the large intestine start overgrowing in the small intestine. This disrupts digestion, fermentation patterns and gut motility. To go one step further, there’s also SIMO – small intestinal methanogen overgrowth. Methanogens are a bit like bacteria, but not quite. Technically they’re archaea.
In short, SIBO bacteria produce hydrogen gas, which usually = diarrhoea and SIMO archaea produce methane gas which usually = constipation.
Overall, common symptoms include bloating, constipation, diarrhoea, reflux, nausea and food intolerances.
Left untreated, SIBO and/or SIMO can lead to leaky gut (intestinal hyperpermeability), which may cause or worsen pain, inflammation, headaches, migraines, auras, and skin problems.
Why SIBO and SIMO are more common in endometriosis
Altered gut motility
People with endometriosis often experience slowed gut motility. This can be due to inflammation, nervous system dysregulation or pelvic floor dysfunction. When motility slows, bacteria and archaea have more time to accumulate in the small intestine.
The role of methane
Methane-producing microbes, often referred to as methanogens, are strongly associated with constipation. Methane slows transit time even further, creating a feedback loop that makes SIBO/SIMO harder to resolve.
Pelvic floor dysfunction
Pain leads to guarding. Guarding leads to dysfunction. Pelvic floor dysfunction can impair bowel movements and contribute to incomplete evacuation, which further feeds into microbial overgrowth.
Inflammation and immune dysregulation
Endometriosis is a systemic inflammatory condition. Chronic inflammation alters the gut environment and immune surveillance, making it easier for dysbiosis and overgrowth to develop.
How SIBO and SIMO can worsen endometriosis
This relationship goes both ways.
SIBO contributes to increased intestinal permeability, also known as leaky gut. This allows inflammatory compounds such as hexa-lipopolysaccharides (hexa-LPS) to enter circulation and amplify systemic inflammation.
There is also an indirect effect on oestrogen metabolism. While SIBO itself is not the oestrobolome, it contributes to a dysbiotic environment that can impair healthy oestrogen clearance.
Furthermore, constipation can lead to oestrogen being recycled back into circulation, contributing to the overall pool of oestrogen.
In addition, gas production and bloating can increase intra-abdominal pressure, which may worsen pelvic pain and discomfort.
What to do about it
Test, don’t guess
Breath testing can help differentiate between hydrogen and methane dominant patterns, which informs treatment direction. For best accuracy, choose a SIBO test that tests all three substrates including lactulose, fructose and glucose.
Address motility
Supporting the migrating motor complex is key. This may include meal spacing, prokinetics and nervous system regulation.
Treat the overgrowth
This may involve herbal antimicrobials, probiotics, pre-biotics, gut-healing nutrients and a structured and individualised protocol.
Treat the underlying cause
This is essential to preventing SIBO/SIMO from returning or prolonging remission. Underlying causes may include condiitons such as low stomach acid, PPI-use, stress, antibiotics, connective tissue disorders, appendectomy, gastro andd food poisoning.
Support the gut environment
Repairing the gut lining, reducing inflammation and rebuilding microbial diversity is essential for long-term outcomes.
Final thoughts
If you are only treating endometriosis locally without considering the gut, you are likely missing a major piece of the puzzle. Addressing SIBO can be a turning point for many people who feel stuck in persistent bloating and pain.
This is exactly what me and my team can help you with. Head to “work with me” up the top to book a consult or package.
