Can Probiotics Transform the Vaginal Microbiome?
The term "probiotics" appears on the packaging of yogurts, kimchi, kombucha, sodas and supplements. If you eat or drink any of these products, beneficial bacteria will make their way to your gut and with digestion. Consuming probiotics is synonymous with having good gut health for many of us, except that—our definition of probiotics is ​​incomplete.
Vaginal probiotics promise to seed the vagina with "good" microbes that keep the pH and odor in check and support the health of the vaginal and urinary ​​tract. However, most of the claims to support them. Some (probiotics) to treat bacterial, yeast and sexually transmitted infections, but that supports FDA clearance and large-scale marketability.
Claims without rigorous scientific proof, though, have permeated the supplement industry, with vaginal probiotics being advertised for their supposed health benefits. While manufacturers cannot claim that supplements treat diseases, they are without needing any proof. As a result, vaginal probiotics, available in the form of oral pills and vaginal suppositories, create the illusion of improved vaginal health to their customers.
Still, vaginal probiotics may turn into therapeutic solutions as the composition of vaginal microbiome and conditions that lead to dysbiosis—an imbalance in vaginal microbiota—are better understood. More research in the vaginal microbiome field will help to create strategies for improving the effectiveness of vaginal probiotics in the ​​future.
What Does a Healthy Vaginal Microbiome Look Like?
The is not static. Microbial communities shift with , including birth, pre-puberty, puberty and menopause. Genetics, geography, ethnicity and lifestyle . Defining a disease-free vaginal state is, therefore, complicated; but, in general, the vaginal microbiota can be classified into 5 (CSTs). These CSTs can be thought of as the 5 most likely combinations to make up the vaginal microbiota in women of reproductive age.
Lactobacilli Species Dominate the Vaginal Microbiome
Lactobacilli species during reproductive years, but Lactobacilli found in the vagina are not the same as the ones that reside in the gut. In fact, although 250 types of Lactobacilli are known in nature, 4 out of 5 CSTs are dominated by Lactobacilli species: L. crispatus, L. gasseri, L. iners and L. jensenii, which are generally known for their . For instance, these organisms convert sugars in the vaginal walls to lactic acid, generating a slightly acidic environment that is hostile to incoming pathogens. Additionally, they produce antimicrobial peptides, such as bacteriocin, to kill competing microbes, and can even physically take up space to keep pathogens from establishing themselves.
CST-IV consists of a low proportion of L. iners and abundant anaerobic bacteria, often linked to an increase in susceptibility to . For example, bacteria known to be associated with (BV)—a vaginal infection characterized by an unusual discharge, fishy odor and vaginal discomfort—are commonly found in this CST.
Bifidobacterium's Protective Role in Vaginal Health
Although Lactobacilli dominate a healthy vaginal microbiota, another bacterial species with the ability to release lactic acid, as well. These bacteria can exist side-by-side with Lactobacilli. But reports find in 5-10% of healthy reproductive-aged women, suggesting they could potentially correspond to a new ​​CST.
Overall, Lactobacilli and Bifidobacteria are indicators of a healthy vaginal microbiome, but there are limited data to support whether using probiotics to replenish either of these species can improve vaginal health and alleviate ​​infections.
What Makes the Vaginal Microbiome Unhealthy?
Microbes That Lead to Bacterial Vaginosis
For example, facultative and obligate anaerobes, such as Gardnerella vaginalis, Atopobium vaginae and Prevotella can lead to BV. Yet, of reproductive age who harbor G. vaginalis and A. vaginae develop symptoms. Studies also show that , blurring the lines between a healthy and diseased vaginal state.
Microbes That Lead to Aerobic Vaginitis
If aerobes, such as Group B Streptococcus, Escherichia coli and Staphylococcus aureus colonize the vagina, the outcome could be (AV) with symptoms similar to BV. Presence of these atypical microbes raises the vaginal pH to be greater than 4.5, disturbs the balance of non-pathogenic and pathogenic microbial members and induces host inflammation. Even in the case of AV patients, Lactobacilli species, such as , and a high prevalence of Lactobacilli species has been observed in women with severe (VVC) fungal infections. Such complexity suggests the need to understand community dynamics rather than focusing on a few microbes as indicators of good vaginal ​​health.
Can Probiotics Be Used to Supplement a Healthy Vaginal Microbiome?
Yet, currently sold vaginal probiotics rely on the idea that more "good" microbes will translate to better health, and they fail to shift the microbial population of the vaginal microbiome toward a healthy state. Microbial population research indicates that appropriate doses of a number of beneficial microbes (as opposed to the introduction of only a few Lactobacilli species) might be needed to shift the state of dysbiosis in the vagina. Could probiotics seed beneficial microbes at the site of infection and aid in removal of pathogens?
Preventing High Recurrence of Infection After Antibiotic Treatment
for vaginal infections, but they only offer temporary relief. For example, within 6 months of antibiotic therapy. The high rate of recurrence is tied to way that antibiotics act; they not only eliminate pathogens, but can also disrupt healthy microbiomes. Several trials have explored the use of observed in patients with BV. However, many of these studies use , rather than those tailored to the vaginal microbiome.
Differences Between Gut and Vaginal Lactobacilli Species
Some scientists that the differences in the efficacy to treat vaginal infections could be a result of use of gut-specific Lactobacilli that aren't inherent residents of the vagina. For example, in a study examining the effects of probiotics on BV, , L. rhamnosus GR-1 and L. reuteri RC-14, and their outcomes were compared to those of a placebo group. No significant differences were found between the 2 groups. In another case, L. rhamnosus GR-1 and L. fermentum RC-14 showed effectiveness as compared to L. rhamnosus GG in healthy women to restore vaginal flora in case of asymptomatic BV.
Probiotic Delivery Method: Surviving or Avoiding Stomach Acids
Scientists examined whether L. rhamnosus and L. gasseri can colonize patients with BV through vaginal application following antibiotic therapy. They ran the study in 2 different populations, one from and the other from . The cure rates for BV were inconsistent in the 2 populations, suggesting that vaginal application is not the only deciding factor to treat vaginal infections. Scientists would need to find the reason behind the variability in outcomes among patients from different parts of the world.
Recently, trials have begun using , a vaginal Lactobacillus species to be the most protective for vaginal health. Lactin-V, a L. crispatus intravaginal suppository probiotic, showed a reduction in repeat (UTIs) and . Although these studies only involved a few hundred participants, they combined antibiotics with probiotics and showed L. crispatus could successfully colonize the vagina. Additionally, was shown to halve the recurrence of BV in patients compared to the placebo group.
What Is Needed to Make Probiotics Effective Therapeutics for Vaginal Health?
Assessing Probiotics as Short- or Long-Term Interventions
Taken together, studies (to date) demonstrate the promise of vaginal probiotics in treating a series of hard-to-treat vaginal infections. Probiotics can colonize the vagina and improve recovery rates, but identifying how probiotics can remain effective long-term is crucial to making them a successful intervention. It has been challenging to determine the reasons behind the success or failure of multiple studies, due to variations in the strains of Lactobacilli used, dose, type (oral or vaginal) and length of intervention.
FDA-Approval
Having FDA-approved vaginal probiotics could be a game-changer, not only for treating vaginal infections, but also for decreasing the risk of acquiring sexually transmitted infections, , and that are linked to dysbiosis. Until then, over-the-counter vaginal probiotics cannot claim or be expected to effectively treat vaginal infections.
Effectiveness and Optimal Dosing
Standards need to be set on how to test vaginal probiotics for their effectiveness. Manufacturers should identify the optimal dose of different vaginal probiotics to colonize the vagina, whether taken orally or inserted vaginally. Further, there needs to be evidence that microbes (probiotics) in the blend are able to shift the vaginal microbiome toward a healthy state for a given period of time and treat dysbiosis. Such strategies will both improve the quality of existing probiotic supplements and their potential to become FDA-approved therapeutics.
Finally, while manufacturers claim that vaginal probiotics "optimize vaginal health," there is no conclusive evidence on how to optimize the vaginal niche in healthy individuals. There is a gap in the understanding of how microbial populations can transition from a healthy to a diseased state. Until more is known, it is best to allow vaginal microbes to maintain their natural balance. While taking a probiotic may not harm the vaginal microbiota, it is unlikely that current supplements have any significant benefit.
Microbial communities exist on, in and around people, plants, animals, soil, oceans and the atmosphere—making the microbiome relevant to almost everything. Learn more about microbiome composition, development and function—in people and beyond.
