The Gut-Endometriosis Connection: Why Probiotic Therapy Could Transform Your Treatment

If you're living with endometriosis, you've likely been told it's all about hormones and inflammation. But what does that actually mean??

While estrogen certainly plays a role, emerging research confirms that your gut and vaginal microbiome may also be key players in both the development and progression of endometriosis — and in your ability to conceive if that is your goal.

Understanding the Microbiome-Gut-Brain Axis in Endometriosis

Endometriosis affects approximately 6-10% of women of reproductive age, and can cause debilitating symptoms including severe dysmenorrhea (painful periods), chronic pelvic pain, bowel changes, infertility, fatigue, and depression. I heard the average amount of time it takes for a woman to get diagnosed with endometriosis is 7 yrs. That is A LOT of doctor visits, pain medications, days off work, and unexplained chronic symptoms. But here's what many maybe don't realize: up to 23% of endometriosis patients experience gastrointestinal symptoms that can overlap with irritable bowel syndrome (IBS), and women with endometriosis have a three-fold increased risk of developing IBS. I wonder how often endometriosis has been mis-diagnosed as “IBS” and fobbed off or not investigated further.

But this isn't a coincidence. The microbiota-gut-brain axis — the communication network between your gut bacteria, your brain, and your reproductive system — plays a crucial mechanistic role in endometriosis.

The Oestrobolome: Your Gut's Control Over Oestrogen

One of the most significant discoveries in endometriosis research is the concept of the "oestrobolome" — the collection of gut bacteria capable of metabolizing oestrogens. These bacteria produce enzymes like β-glucuronidase that deconjugate estrogen into its active form.

When you have gut dysbiosis (an imbalance of gut bacteria), you may have:

• Increased β-glucuronidase-producing bacteria (like E. coli and many others)

• Higher levels of circulating active oestrogens

• Enhanced oestrogen-driven endometrial tissue proliferation outside the uterus

Research has shown that antibiotic treatment helps reduce endometriosis symptoms by modulating the gut microbiota (not that I would recommend that as a form of treatment! but I WOULD do a microbiome analysis and provide appropriate herbs or nutraceuticals). In animal studies, metronidazole reduced endometriotic lesion growth and inflammation by reducing specific bacterial populations. When these mice were given fecal transplants from mice with endometriosis, the lesions and inflammation returned — providing strong evidence that gut microbiota is related to endometriosis and promotes lesion progression.

Gut Dysbiosis in Endometriosis: What's Different?

Studies comparing women with and without endometriosis have found:

• Lower diversity of gut microbiota

• Higher Firmicutes-to-Bacteroidetes ratio in stage 3/4 endometriosis

• Elevated levels of pathogenic bacteria including Gardnerella, Streptococcus, Escherichia, and Shigella

• Reduced levels of beneficial lactobacilli

This dysbiosis creates a chronic inflammatory state through several mechanisms:

-Increased gut permeability: Disruption of tight junctions allows harmful substances into the bloodstream

-Chronic inflammation: Higher abundance of pathogenic bacteria triggers persistent immune activation

-Altered metabolites: Changes in fatty acid metabolism and inflammatory mediators

The Vaginal Microbiome Connection: BV, Candida, and Fertility

While we often focus on the gut, the vaginal microbiome is equally critical — especially when you're trying to conceive. The research here is particularly compelling:

Bacterial Vaginosis and Conception

Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge among women of childbearing age, affecting approximately 50% of Australian women. (So don’t assume than any unusual discharge is candida! It is really important to differentiate ie test to ensure you are getting the right treatment). Research also suggests that 50% of those affected may also be asymptomatic (ie do not have any symptoms). So I believe that the vaginal microbiome is an important consideration for fertility, or fertility issues, and is definitely worth investigating.

Here's what the research shows:

• BV is three times more common in infertile women than fertile women

• The presence of BV-associated bacteria in the endometrium has been linked to a 3.4-fold increased risk of infertility

• BV is significantly more prevalent in women with tubal infertility compared to those with other causes of infertility

• BV is also associated with a two-fold increased risk of early pregnancy loss

In a cohort study of 867 women undergoing IVF, researchers found that women with BV who conceived had a significantly increased risk of first-trimester miscarriage: 31.6% compared to 18.5% for those with normal vaginal flora. I think this is a heart breaking statistic, with more testing and proactive care in this space, I wonder how many women’s and family’s lives would have been very different.

The mechanism? BV increases your risk of:

-Pelvic inflammatory disease (PID)

-Chronic endometritis (inflammation of the uterine lining)

-Ascending infections that damage the fallopian tubes

-Chronic inflammation that creates a toxic environment for reproduction

-Compromised cervical mucus that makes it harder for sperm to reach the egg

Candida and Conception

Yeast infections may not directly cause infertility, but they can impact your ability to conceive by:

• Altering cervical mucus consistency and pH

• Making it harder for sperm to travel through the cervix

• Creating inflammation that affects the reproductive environment

  all of which are hugely important!’

Probiotic Therapy: The Research That Changes Everything

This is where things get exciting and hopefully bring some light to a rather emotional topic. Multiple studies have demonstrated that probiotic therapy can be transformative for endometriosis management and fertility:

Endometriosis-Specific Research

Lactobacillus gasseri : Suppressed development of endometriosis via activation of natural killer (NK) cells in mice.

-In a randomized, double-blind, placebo-controlled study, tablets containing L. gasseri improved menstrual pain and dysmenorrhea with no adverse effects

-Significantly reduced pain intensity scores after three months of treatment

-Shows promising therapeutic potential for cervical health and HPV

Saccharomyces boulardii

-In a mouse model, oral treatment led to significantly lower volume and size of endometriotic lesions after both 4 and 12 weeks

-Decreased pain response

Combination Lactobacillus Therapy

-A pilot randomized triple-blind placebo-controlled trial found that oral lactobacillus could significantly alleviate endometriosis-associated pain

-In one study, dysmenorrhea scores dropped from 6.53 to 3.07 in the probiotic group after 8 weeks, compared to 5.60 to 4.47 in controls

The mechanisms include:

-Increased IL-12 concentration and NK cell activity

-Reduced growth of endometriotic lesions

-Decreased inflammatory markers (IL-1β, TNF-α, IL-6, TGF-β1)

-Modulation of the immune response

For Vaginal Health and Fertility

Lactobacillus crispatus

-In a double-blind, placebo-controlled trial, vaginal L. crispatus after metronidazole treatment resulted in significantly lower BV recurrence: 30% vs 45% at 12 weeks

-L. crispatus-dominated vaginal microbiomes have been linked with higher rates of embryo implantation and live births after IVF

-Women with lactobacillus-dominated vaginal microbiomes have higher pregnancy rates with assisted reproductive technology

Beyond Probiotics: Supporting Your Microbiome

Research also supports these complementary approaches:

Dietary Interventions:

-Low FODMAP diet: 72% of endometriosis patients with IBS saw improvement in symptoms over 50% after 4 weeks. This tells me that we should be looking at SIBO diagnosis and treatment.

-Omega-3 polyunsaturated fatty acids: May reduce endometriosis risk by modulating inflammation and can change gut microbiota composition

-Fruits, vegetables, dairy products: Associated with attenuated risk of endometriosis. ie a wholefood, Medditerean diet.

-Mediterranean diet: Related to reduction in general pain and overall improvement

Nutrients and Supplements:

-Vitamin D, C, and E

-Resveratrol, curcumin, and catechin ie green tea (though more clinical trials needed)

-Alpha-linolenic acid (ALA): Shown to reduce inflammatory response and improve the abdominal inflammatory environment in mice

What Does This Mean for Adenomyosis?

While adenomyosis is distinct from endometriosis (occurring when endometrial-like tissue embeds deep within the uterine muscular wall), both conditions share similar characteristics:

-Both are considered oestrogen-driven

-Both involve chronic inflammation

-Both can cause severe dysmenorrhea (painful periods), dyspareunia (painful intercourse), and fertility challenges

-Both may benefit from microbiome-based therapeutic approaches

The research on probiotics for adenomyosis is still emerging, but given the shared pathophysiology with endometriosis, addressing gut and vaginal dysbiosis may offer similar benefits.

Research suggests potential reduction in Lactobacillus and increased colonisation of Enterobacteriaceae and Candida, and highlighted potential Lactobacillis therapy in Adenomyosis therapy.

Practical Steps: Implementing Probiotic Therapy

If you're considering probiotic therapy for endometriosis, adenomyosis, BV or fertility support, work with a healthcare professional that has experience in this field. Test microbial species and vaginal PH to ascertain the best therapeutic treatment, including stain specific probiotics.

Take probiotics consistently for at least 8-12 weeks to see results

For Vaginal Health and Fertility:

If you have BV, treat it promptly and appropriately, with follow up testing to confirm outcomes. I often suggest working with sexual partners also, especially if you do not use condoms.

If using antibiotic treatment, support with vaginal probiotics containing L. crispatus or L. rhamnosus and dietary/lifestyle support.

Consider reproductive probiotics specifically formulated for vaginal health

Tests I often like to use are either Nutripath or Juno Bio

For Overall Microbiome Support:

Eat a diverse, fiber-rich diet

Include fermented foods

Minimize processed foods and added sugars, preservatives, gums etc

Manage stress (it affects your microbiome!)

Avoid unnecessary antibiotics when possible

The Future of Endometriosis Treatment

While there's still no cure for endometriosis, understanding the role of the microbiota-gut-brain axis opens exciting new avenues for treatment. Probiotics offer several advantages over conventional treatments:

Fewer side effects compared to hormonal therapies

Can be used alongside other treatments

Address root causes rather than just symptoms

Support overall health beyond endometriosis

The Bottom Line

Your gut and vaginal microbiome aren't just passive bystanders in endometriosis — they're active players that can either fuel inflammation and disease progression or help reduce symptoms and support fertility.

The research is clear:

Gut dysbiosis contributes to endometriosis through estrogen metabolism and chronic inflammation

BV and vaginal dysbiosis significantly impact fertility and pregnancy outcomes

Probiotic therapy has demonstrated real benefits for pain relief, lesion reduction, and reproductive health

A multimodal approach addressing the microbiome alongside conventional treatments may offer the best outcomes

If you're struggling with endometriosis, chronic pelvic pain, or fertility challenges, it's time to look beyond just hormones. Your microbiome deserves a seat at the treatment table.

Note: This information is for educational purposes only and should not replace medical advice. Always work with qualified healthcare practitioners when implementing new treatment protocols, especially if you're trying to conceive or currently pregnant.

References

Research cited in this article includes studies from Frontiers in Microbiology, BMC Medicine, Gut Microbiota for Health, Reproduction and Fertility, Cell Death Discovery, The American Journal of Obstetrics & Gynecology, and other peer-reviewed journals published between 2022-2024.