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Understanding the vaginal microbiome essential to human health

Understanding the microorganisms that inhabit the vagina, also known as the vaginal microbiome, is extremely important for women, their offspring and sexual partners. 

Photo of Dr. Gregor Reid
St. Joseph's Hospital - 

There are trillions of microorganisms inhabiting your body. The majority of these are positive and essential to your health. They include those microorganisms found in the female reproductive system – a highly diverse environment that is crucial to human survival.

Understanding the microorganisms that inhabit the vagina, also known as the vaginal microbiome, is extremely important for women, their offspring and sexual partners. Dr. Gregor Reid recognizes this importance through his research into lactobacilli, the dominant organisms present in the healthy vagina of most women. 

Dr. Reid is a Lawson microbiome and probiotics scientist and director of the Canadian Research and Development Centre for Probiotics. His interest in the vaginal microbiome began over 33 years ago.

“In the human gut, the microbiome differs with diet. But there is a global similarity to the vaginal microbiome,” said Dr. Reid. “From early in my career, I suspected a connection between this uniformity and the female’s critical role in reproduction.”

Harmful bacteria, also known as pathogens, can invade the vaginal microbiome to produce a more highly diverse state. This leads to the displacement of lactobacilli. It can also lead to bacterial vaginosis (BV) and the easier contraction of urinary tract infections (UTIs). These two ailments account for numerous physician visits each year and a reduction in a woman’s quality of life.

Mediating pregnancy and infant development

Research suggests that lactobacilli mediate complex changes that occur during pregnancy. If harmful pathogens invade and persist, inflammation and premature delivery can occur during pregnancy.

“The mechanisms behind the displacement of lactobacilli are not clear,” says Dr. Reid. “However, a number of factors can increase risk of BV. These include douching, sexual intercourse, lower estrogen levels and aging. It’s crucial that we conduct further research into these processes.”

Studies also suggest that the human fetus is exposed to the mother’s lactobacilli prior to birth, in addition to exposure during vaginal birthing. Again, understanding of this process and its significance is limited but warrants further investigation, says Reid. We need to further understand how exposure affects an infant’s immunity, metabolism and behavior in both early and later life.

“We’re seeing a dramatic rise in C-sections and a drop in breastfeeding,” says Reid. “If a developing child is not fully exposed to the mother’s lactobacilli, does this provide an opportunity for harmful bacteria to proliferate? This may cause repercussions to the offspring’s own future reproductive health.”

The role of probiotics

As research begins to focus on restoring a lactobacilli-dominant state, probiotics have been explored. However, attempts have presented challenges. “When probiotics are administered vaginally in a dried form, the lactobacilli fail to colonize long-term,” says Dr. Reid. “A study introducing lactobacilli in more natural form may lead to successful colonization. This has been the case in other areas like fecal transplantation.”

Challenges and opportunities

There are a number of other challenges when it comes to the study of the vaginal microbiome. This includes the lack of suitable animal models. While there have been recent developments that may lead to better recreations of a female microbiome, Dr. Reid explains that it will be difficult to mimic the many complexities of the female reproduction system. These include the menstrual cycle, immune responses, the use of douches, sexual intercourse and more.

“To fully understand female health, reproduction and infant development, we need to better understand lactobacilli,” said Dr. Reid. “We know that lactobacilli may help to combat herpes and environmental toxins, improve sperm motility, and even self-cure episodes of UTI and/or BV. What we are slowly uncovering is an understanding of the processes behind these interactions.”

Dr. Reid recently published a paper on this subject, “Cervicovaginal Microbiomes–Threats and Possibilities”, in the publication Trends in Endocrinology & Metabolism. Dr. Reid’s own research is currently focused on compounds with the capacity to expand the proportion of lactobacilli at the expense of pathogens. The goal of this research is to improve the health of women across Canada and around the world.