Whether you are trying to conceive for the first time or are seeking professional help after a year or even years of attempts, the evidence is clear. Microbes matter.

The microbiome (a collection of bacteria, viruses, and other organisms that symbiotically inhabit the human body) is a new frontier in reproductive health. The past few decades of research give strong evidence that your microbes—both women’s and men’s—are important actors. This is welcome news. It adds another target—one which may be easier (and far cheaper) to address—for those preparing and/or struggling to conceive.

Women

Unlike healthy profiles seen in other regions such as the gut, reproductive microbiota in healthy women of procreative age show low diversity. This means that only a few lactobacilli species account for up to 95% of the total bacteria. Their dominance turns out to be a good thing in this context.

Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners, and Lactobacillus jensenii are the most represented in the vagina of healthy women. Yet different women host different microbes, a distinction most apparent in Hispanic and Black women. What’s more, infertile women host a different microbiota than healthy and fertile women.

Lactobacilli and related organisms help maintain a healthy vaginal microbiota free of pathogens (microbes that can cause disease) by several mechanisms: lactic acid, hydrogen peroxide, and bacteriocins production; physical barrier strengthening; immune activation.

Several common disorders may interfere with this ideal female reproductive system. Bacterial vaginosis (BV), endometriosis, pelvic inflammatory disease (PID), and polycystic ovary syndrome (PCOS) are all linked to poor reproductive outcomes. Dysbiosis (fewer lactobacilli and higher diversity) may lead to or result from inflammation and infections.

Antibiotics are the go-to treatment for infections. But in BV, for example, nearly half of women treated have a recurrence within one-year post-treatment. After all, antibiotics also kill beneficial microbes that fight pathogens.

A better strategy may be to use probiotics alone (success has been seen in BV) or after the course of antibiotics to restore a healthy microbiota. Oral probiotics are the norm but vaginal application is faster and more targeted.

Several oral and vaginal probiotics containing Lactobacillus spp. are available in the marketplace. Many of them may include one or more of these species: L. crispatus, L. gasseri, L. plantarum, L. reuteri, and L. rhamnosus.

With assisted reproductive technology (ART), success rates are improved when women have healthy low-diversity dominance with lactobacilli. Colonizing the transfer-catheter tip with L. crispatus at the time of embryo transfer may increase the rates of implantation and live birth rate while decreasing the rate of infection.

Take the Next Step – Schedule an Appointment

Taking care of vaginal microbes

• Use only mild soaps and never douche.*
• Manage vaginal pH: a more acidic environment facilitates the growth of Lactobacillus species and inhibits pathogens.
• Include fermented foods and beverages at every meal if possible. Yogurt, kombucha, kefir, kimchi, and fermented cheeses are the most known but other foods can be fermented too. The actual probiotic content is not established.
• Include prebiotic foods so that your beneficial microbes can flourish. Plants that are rich in prebiotics include onions, garlic, bananas, chicory root, and Jerusalem artichokes. Prebiotics added to foods or supplements include galacto- oligosaccharides (GOS), fructo-oligosaccharides (FOS), oligofructose (OF), chicory fiber, and inulin.
• Eat a healthful diet such as the Mediterranean diet.
• Avoid tobacco and alcohol.
• Exercise regularly.
• Consider a supplement (with probiotic bacteria described before) that may repopulate the bacteria known to exist in a healthy ecosystem.

* The term, douche, which means “to wash” or “to shower” in French, is often done with prepackaged products. The solution can alter the normal pH as well as the balance of bacteria in the vagina. Though commonly practiced and touted in ads targeting women, vaginal douching is linked to many adverse outcomes including BV, cervical infection, PID, ectopic pregnancy (implantation of a fertilized egg outside the uterine cavity), cervical cancer, and as a risk factor for HIV acquisition. The American College of Obstetricians and Gynecologists (ACOG) recommends that women avoid vaginal douching.

Men

Semen delivers sperm but also vital nutrients for a successful pregnancy. Once thought to be a sign of infection, bacteria in semen are now known to compose a microbiome, which can impact the fertilization and growth of a healthy fetus.

A man’s seminal microbiota can be healthy or unhealthy. Ensuring a healthy seminal microbiome is an important step in health measures before trying to conceive. And know that making sure your microbiota is in good shape is recommended for all men—not just the infertile—who wish to optimize the health of their future child.

Certain strains of lactobacilli may have a protective role in the male genital tract, similar to what is seen in females.

If pathogens (e.g. Escherichia coli, Chlamydia trachomatis) prevail and lactobacilli are reduced, sperm function and quality will suffer. Pathogens drive inflammation and oxidative stress ensues, a condition that is linked to infertility, reduced sperm motility, sperm DNA damage, and increased risk of recurrent miscarriages and genetic diseases. Some 30% to 80% of male sub-fertility may be associated with oxidative stress that damages sperm and can decrease the success of in vitro fertilization (IVF) techniques.

Though antibiotics have traditionally treated these pathogens, increasing antibiotic drug resistance calls for alternate therapies. Correcting dysbiosis of the microbiota to deter pathogens is a solution with big potential.

Probiotics for men are thought to enhance male fertility through improved sperm parameters —concentration (number per unit), motility (swimming ability), and morphology (shape) —as well as testosterone levels. Several studies using selected strains of lactobacilli in animals and humans showed positive effects.

Prebiotics too were able to improve some semen factors in both animal and human studies.

Combining the two in what is known as a symbiotic may be even better in enhancing sperm features and testosterone levels.

Taking care of semen microbes

• Include fermented foods and beverages at every meal if possible. Yogurt, kombucha, kefir, kimchi, and fermented cheeses are the most known but other foods can be fermented too. The actual probiotic content may be variable.
• Include prebiotic foods so that your beneficial microbes can flourish. Plants that are rich in prebiotics include onions, garlic, bananas, chicory root, and Jerusalem artichokes. Prebiotics added to foods or supplements include galacto- oligosaccharides (GOS), fructo-oligosaccharides (FOS), oligofructose (OF), chicory fiber, and inulin.
• Consider a supplement (with probiotic bacteria described before) that may repopulate the bacteria known to exist in a healthy ecosystem.

Couples therapy

Partners share microbes during sexual intercourse. This “seminovaginal” microbiome may foster harmful or helpful exchanges of organisms.

Takeaway

Probiotics may boost fertility in both men and women. Altering the microbiome has been shown to enhance male fertility by reducing oxidative stress and improving testosterone levels and sperm quality. And in women, probiotics may restore a healthy genital tract with predominant Lactobacillus species, preventing pathogens from upending the balance, which can lead to complications, such as bacterial vaginosis, pre-term birth in pregnancy, and infertility.

Both fertility and your future child depend on your choices today. Start now.

Key references

Bagnall, Paulette, and Denise Rizzolo. “Bacterial vaginosis: A practical review.” JAAPA : official journal of the American Academy of Physician Assistants vol. 30,12 (2017): 15-21. doi:10.1097/01.JAA.0000526770.60197.fa

Delaney, M L, and A B Onderdonk. “Nugent score related to vaginal culture in pregnant women.” Obstetrics and gynecology vol. 98,1 (2001): 79-84. doi:10.1016/s0029-7844(01)01402-8

Farahani, Linda et al. “The semen microbiome and its impact on sperm function and male fertility: A systematic review and meta-analysis.” Andrology vol. 9,1 (2021): 115-144. doi:10.1111/andr.12886

Haahr, T et al. “Abnormal vaginal microbiota may be associated with poor reproductive outcomes: a prospective study in IVF patients.” Human reproduction (Oxford, England) vol. 31,4 (2016): 795-803. doi:10.1093/humrep/dew026

Jodar, Meritxell et al. “The protein and transcript profiles of human semen.” Cell and tissue research vol. 363,1 (2016): 85-96. doi:10.1007/s00441-015-2237-1

Koedooder, Rivka et al. “Identification and evaluation of the microbiome in the female and male reproductive tracts.” Human reproduction update vol. 25,3 (2019): 298-325. doi:10.1093/humupd/dmy048

Moreno, Inmaculada, and Carlos Simon. “Deciphering the effect of reproductive tract microbiota on human reproduction.” Reproductive medicine and biology vol. 18,1 40-50. 1 Nov. 2018, doi:10.1002/rmb2.12249

Ravel, Jacques et al. “Bacterial vaginosis and its association with infertility, endometritis, and pelvic inflammatory disease.” American journal of obstetrics and gynecology vol. 224,3 (2021): 251-257. doi:10.1016/j.ajog.2020.10.019

Ravel, Jacques et al. “Vaginal microbiome of reproductive-age women.” Proceedings of the National Academy of Sciences of the United States of America vol. 108 Suppl 1,Suppl 1 (2011): 4680-7. doi:10.1073/pnas.1002611107

Rizzo, Anthony E et al. “The Female Reproductive Tract Microbiome-Implications for Gynecologic Cancers and Personalized Medicine.” Journal of personalized medicine vol. 11,6 546. 11 Jun. 2021, doi:10.3390/jpm11060546

Scaruffi, Paola et al. “Oral Antioxidant Treatment of Men Significantly Improves the Reproductive Outcome of IVF Cycles.” Journal of clinical medicine vol. 10,15 3254. 23 Jul. 2021, doi:10.3390/jcm10153254

Sirota, Ido et al. “Potential influence of the microbiome on infertility and assisted reproductive technology.” Seminars in reproductive medicine vol. 32,1 (2014): 35-42. doi:10.1055/s-0033-1361821

Tomaiuolo, Rossella et al. “Microbiota and Human Reproduction: The Case of Female Infertility.” High-throughput vol. 9,2 12. 3 May. 2020, doi:10.3390/ht9020012

Tomaiuolo, Rossella et al. “Microbiota and Human Reproduction: The Case of Male Infertility.” High-throughput vol. 9,2 10. 13 Apr. 2020, doi:10.3390/ht9020010

Author Bio

Clare Fleishman MS RDN, a registered dietitian with a master’s degree in nutrition science, has worked in clinical, community, and corporate settings globally. In hopes of bridging the gap between science and health, she has published widely across many platforms: newspapers, magazines, continuing education curricula, and scientific organizations among others. Fleishman launched the website ProbioticsNow.com to share the cascade of discoveries in the microbiome. Her 2013 book Globesity explored surprising contributors to the obesity pandemic. FERTILITY: Why Microbes, Weight & Nutrition Matter was published in 2022.

NutritionConsult.info@Gmail.com

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The information provided should not be used to diagnose or treat any medical condition. For diagnosis or treatment of any medical problem, consult your physician. The publisher and author are not responsible for any specific health or allergy needs that may require medical supervision and are not liable for any damages or negative consequences from any treatment, action, application, or preparation, to any person reading or following the information in this book. References are provided for informational purposes only and do not constitute an endorsement of any websites or other sources. Although the author and publisher have made every effort to ensure that the information in this book was correct at press time, the author and publisher do not assume and hereby disclaim any liability to any party for any loss, damage, or disruption caused by errors or omissions, whether such errors or omissions result from negligence, accident, or any other cause.