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 help with digestion. Consuming probiotics is synonymous with having good gut health for many of us—except that our definition of probiotics is incomplete.
Probiotics are more than a mix of gut-friendly bacteria. They are a blend of live microorganisms with benefits to the body—beyond the health of the digestive tract. For example, the skin, mouth, penis and vagina have unique microbiomes of their own. While commercial probiotics catering to all of these microbiomes do not yet exist, vaginal probiotics do. They dominate the shelves of drugstores and supermarkets with the notion that “vaginal” probiotics can boost vaginal health, similar to how “gut” probiotics can improve gut health.
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 lack scientific evidence to support them. Some small-scale clinical trials have tested the use of vaginal microbes (probiotics) to treat bacterial, yeast and sexually transmitted infections, but none have demonstrated effectiveness 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 allowed to suggest health benefits from their products 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 vaginal microbiome is not static. Microbial communities shift with different seasons of life, including birth, pre-puberty, puberty and menopause. Genetics, geography, ethnicity and lifestyle factors also impact vaginal microbiome populations.
Defining a disease-free vaginal state is, therefore, complicated; but, in general, the vaginal microbiota can be classified into 5 community state types (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 occupy about 70% of the healthy vaginal microbiome 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 protective qualities.
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 vaginal infections. For example, bacteria known to be associated with bacterial vaginosis (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, Bifidobacterium, seems to play a protective role in the vagina as well. These bacteria can exist side-by-side with Lactobacilli. But reports find Bifidobacterium-dominant microbiome 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?
A single microbe cannot define a healthy or disease-free vagina, and categorizing microbes as exclusively “good” or “bad” is often misleading. More broadly speaking, vaginal infections are a result of dysbiosis, which may be caused by (or related to) oscillating hormone levels, douching and sexual activity. The process begins when Lactobacilli-induced acidic surroundings are disrupted, and other microbes start taking residence in the vagina, ultimately causing infections.
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, not all people of reproductive age who harbor G. vaginalis and A. vaginae develop symptoms. Studies also show that G. vaginalis can coexist with Lactobacilli in a healthy vagina, 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 aerobic vaginitis (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 L. gasseri, can dominate 25% of the microbes in the vagina, and a high prevalence of Lactobacilli species has been observed in women with severe vulvovaginal candidiasis (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
Antibiotics are the standard-of-care treatment for vaginal infections, but they only offer temporary relief. For example, 50% of women experience a recurrence of BV 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 probiotics to prevent the high recurrence rates observed in patients with BV. However, many of these studies use probiotic formulations specific to gut microbiota, rather than those tailored to the vaginal microbiome.
Differences between gut and vaginal lactobacilli species
Some scientists argue 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, pregnant women with BV were given oral gut probiotics, 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
Oral supplementation, in part, can also lower the chances of probiotics making it to the vagina. Not all Lactobacilli species can tolerate stomach acids and bile salts. To avoid the shortcomings of oral pills, (i.e., limited survival through the gastrointestinal tract), researchers have started to study the impact of introducing probiotics directly into the vagina and even combining them with antibiotic therapy to enable recolonization after the clearance of pathogens. This strategy has shown limited success, despite its promising approach.
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 Scandinavia and the other from South Africa.
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 L. crispatus, a vaginal Lactobacillus species considered to be the most protective for vaginal health. Lactin-V, a L. crispatus intravaginal suppository probiotic, showed a reduction in repeat urinary tract infections (UTIs) and BV.
Although these studies only involved a few hundred participants, they combined antibiotics with probiotics and showed L. crispatus could successfully colonize the vagina. Additionally, another L. crispatus strain 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, spontaneous preterm birth, pelvic inflammatory disease and gynecological cancers 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.
Citation:
Can probiotics transform the vaginal microbiome? (2025, May 1)
retrieved 1 May 2025
from https://medicalxpress.com/news/2025-05-probiotics-vaginal-microbiome.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
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 help with digestion. Consuming probiotics is synonymous with having good gut health for many of us—except that our definition of probiotics is incomplete. Probiotics are more than a mix of gut-friendly bacteria. They are a blend of live microorganisms with benefits to the body—beyond the health of the digestive tract. For example, the skin, mouth, penis and vagina have unique microbiomes of their own. While commercial probiotics catering to all of these microbiomes do not yet exist, vaginal probiotics do. They dominate the shelves of drugstores and supermarkets with the notion that “vaginal” probiotics can boost vaginal health, similar to how “gut” probiotics can improve gut health. 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 lack scientific evidence to support them. Some small-scale clinical trials have tested the use of vaginal microbes (probiotics) to treat bacterial, yeast and sexually transmitted infections, but none have demonstrated effectiveness 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 allowed to suggest health benefits from their products 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. The vaginal microbiome is not static. Microbial communities shift with different seasons of life, including birth, pre-puberty, puberty and menopause. Genetics, geography, ethnicity and lifestyle factors also impact vaginal microbiome populations. Defining a disease-free vaginal state is, therefore, complicated; but, in general, the vaginal microbiota can be classified into 5 community state types (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 occupy about 70% of the healthy vaginal microbiome 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 protective qualities. 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 vaginal infections. For example, bacteria known to be associated with bacterial vaginosis (BV)—a vaginal infection characterized by an unusual discharge, fishy odor and vaginal discomfort—are commonly found in this CST. Although Lactobacilli dominate a healthy vaginal microbiota, another bacterial species with the ability to release lactic acid, Bifidobacterium, seems to play a protective role in the vagina as well. These bacteria can exist side-by-side with Lactobacilli. But reports find Bifidobacterium-dominant microbiome 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. A single microbe cannot define a healthy or disease-free vagina, and categorizing microbes as exclusively “good” or “bad” is often misleading. More broadly speaking, vaginal infections are a result of dysbiosis, which may be caused by (or related to) oscillating hormone levels, douching and sexual activity. The process begins when Lactobacilli-induced acidic surroundings are disrupted, and other microbes start taking residence in the vagina, ultimately causing infections. For example, facultative and obligate anaerobes, such as Gardnerella vaginalis, Atopobium vaginae and Prevotella can lead to BV. Yet, not all people of reproductive age who harbor G. vaginalis and A. vaginae develop symptoms. Studies also show that G. vaginalis can coexist with Lactobacilli in a healthy vagina, blurring the lines between a healthy and diseased vaginal state. If aerobes, such as Group B Streptococcus, Escherichia coli and Staphylococcus aureus colonize the vagina, the outcome could be aerobic vaginitis (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 L. gasseri, can dominate 25% of the microbes in the vagina, and a high prevalence of Lactobacilli species has been observed in women with severe vulvovaginal candidiasis (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. 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 Several trials have explored the use of probiotics to prevent the high recurrence rates observed in patients with BV. However, many of these studies use probiotic formulations specific to gut microbiota, rather than those tailored to the vaginal microbiome. Some scientists argue 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, pregnant women with BV were given oral gut probiotics, 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. Oral supplementation, in part, can also lower the chances of probiotics making it to the vagina. Not all Lactobacilli species can tolerate stomach acids and bile salts. To avoid the shortcomings of oral pills, (i.e., limited survival through the gastrointestinal tract), researchers have started to study the impact of introducing probiotics directly into the vagina and even combining them with antibiotic therapy to enable recolonization after the clearance of pathogens. This strategy has shown limited success, despite its promising approach. 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 Scandinavia and the other from South Africa. 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 L. crispatus, a vaginal Lactobacillus species considered to be the most protective for vaginal health. Lactin-V, a L. crispatus intravaginal suppository probiotic, showed a reduction in repeat urinary tract infections (UTIs) and BV. Although these studies only involved a few hundred participants, they combined antibiotics with probiotics and showed L. crispatus could successfully colonize the vagina. Additionally, another L. crispatus strain was shown to halve the recurrence of BV in patients compared to the placebo group. 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, spontaneous preterm birth, pelvic inflammatory disease and gynecological cancers 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. Citation: This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
What does a healthy vaginal microbiome look like?
Lactobacilli species dominate the vaginal microbiome
Bifidobacterium’s protective role in vaginal health
What makes the vaginal microbiome unhealthy?
Microbes that lead to bacterial vaginosis
Microbes that lead to aerobic vaginitis
Can probiotics be used to supplement a healthy vaginal microbiome?
Antibiotics are the standard-of-care treatment for vaginal infections, but they only offer temporary relief. For example, 50% of women experience a recurrence of BV 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.Differences between gut and vaginal lactobacilli species
Probiotic delivery method: Surviving or avoiding stomach acids
What is needed to make probiotics effective therapeutics for vaginal health?
Can probiotics transform the vaginal microbiome? (2025, May 1)
retrieved 1 May 2025
from https://medicalxpress.com/news/2025-05-probiotics-vaginal-microbiome.html
part may be reproduced without the written permission. The content is provided for information purposes only.
