Does your vagina really need a probiotic?

The marketing appears to be ahead of the science when it comes to vaginal probiotics.

Probiotics are everywhere these days, in drinks, pills, and powders, and marketers are suggesting that you need to take them not only for your gut — but also for your vagina.

Many women are heeding the message, says Dr. Caroline Mitchell, assistant professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School. Vaginal probiotic supplements are hugely popular. This includes both probiotic pills and suppository capsules that are inserted into the vagina using an applicator.

The problem is, there is scant evidence to support their effectiveness. "There is almost no evidence that these have benefit for vaginal health. The studies are mostly poorly done and don't adhere to rigorous reporting standards, even if they are randomized trials," says Dr. Mitchell. But that hasn't stopped companies from promoting products for that purpose.

However, while today's vaginal probiotic products should be viewed with a healthy dose of skepticism, that may change in the future as the scientific knowledge in this area builds. In the meantime, here's a rundown of what's known — and unknown — about probiotics and your vaginal health.

Sorting fact from fiction

Vaginal probiotics are touted as a way to introduce live microorganisms into your vagina to improve health. It's true that your vagina, like your digestive tract, is teeming with beneficial bacteria and other microorganisms. Research is increasingly showing that a diverse and healthy gut microbiome plays a role in fine-tuning the immune system and warding off damaging inflammation inside the body that may lead to conditions ranging from heart disease and diabetes to neurodegenerative diseases. When it comes to vaginal health, there are some common gynecological conditions that are thought to be caused by an imbalance of bacteria inside the vagina. More often than not, when women seek out probiotics, they're doing it in an attempt to ease discomfort caused by two of them: bacterial vaginosis and yeast infection, says Dr. Mitchell.

Bacterial vaginosis is the most common vaginal infection in women of childbearing age. There's still a lot that experts don't understand about the condition, but it is associated with an overgrowth of harmful microorganisms, such as Gardnerella vaginalis or Prevotella, which outnumber "healthier" types of vaginal bacteria, including a common organism called Lactobacillus.

Vaginal yeast infection also stems from an imbalance in the vagina. But in this condition, the problem is a fungus called Candida, which overcomes healthy bacteria. Candida can exist normally in the vagina without any problem, but it may cause trouble if it outnumbers other microorganisms.

"There are some women who could benefit from probiotics — at least in theory," says Dr. Mitchell. Among them are women with bacterial vaginosis or yeast infection. For example, when it comes to recurrent bacterial vaginosis, the thinking is that introducing more of the helpful lactobacilli might protect against that overgrowth of harmful organisms and consequently reduce recurrent infections. But proof is lacking, says Dr. Mitchell. If that is shown to be true, a probiotic could be beneficial, but no one is sure. It's not at all clear that taking a probiotic orally will help the vagina in any case.

There are also unknowns related to vaginal yeast infection. "In the vagina, yeast and lactobacilli coexist quite happily, while in the laboratory, lactobacilli can kill yeast," says Dr. Mitchell. So, taking probiotics isn't a scientifically based strategy, because real life circumstances don't match what happens in the laboratory.

For now, the only proven treatments for bacterial vaginosis and yeast infection are antibiotic or antifungal treatments, says Dr. Mitchell.

A solution born of frustration

But sometimes women don't respond to the standard treatments and experience recurrent problems that leave them searching for solutions. Dr. Mitchell says that some women she's encountered are trying not only probiotic supplements, but also alternative treatments they've found on the Internet. These include putting yogurt-soaked tampons, tea tree oil, and even garlic cloves into their vaginas in an effort to introduce beneficial bacteria. These solutions, she says, are not only ineffective but highly inadvisable.

"It's true that a compound in garlic, allicin, has been shown to kill yeast in a laboratory. But you cannot put enough cloves of garlic in your vagina — or take enough oral garlic capsules — to achieve the same effect," says Dr. Mitchell. Tea tree oil also has no demonstrated benefit and can cause irritation. Yogurt-infused tampons don't work either. Many probiotic supplements and most yogurts do contain Lactobacillus bacteria, but it's generally not the same type of Lactobacillus that is found in your vagina. L. crispatus and L. iners are the most common species found in the vagina, while most probiotics and yogurt contain other species, such as L. rhamnosus or L. acidophilus, which are more common in the gut.

Benefit or harm?

There also isn't enough information to determine if introducing new bacteria using probiotics might do more harm than good. "When you take additional bacteria, you don't know what you're messing with," says Dr. Mitchell. "The potential to do harm is probably as big as the potential to do good." One study published in September 2018 in the journal Cell found that when people were given a probiotic after antibiotic treatment, their natural gut bacteria actually took longer to recover than did the gut bacteria of people who didn't take the probiotic.

With all this in mind, should you take a vaginal probiotic? "What I tell people is that, overall, vaginal probiotics are probably a waste of money," says Dr. Mitchell. "But if you are going to pick one and you really want to try one, the probiotics that seem to show some benefit in studies are ones containing Lactobacillus rhamnosusGR-1." Keep in mind that supplements, unlike medications, are not FDA regulated. "Studies have shown that when these products are cultured, they often don't have as much of what is on the label as promised, or don't even contain what is on the label," says Dr. Mitchell. The FDA has also found that some supplements contain potentially dangerous contaminants.

But stay tuned; there may be at least one new option on the horizon. "There is an ongoing trial of a vaginal Lactobacillus crispatus product called Lactin-V," says Dr. Mitchell. "The company is looking to get this FDA approved as a live biotherapeutic, as opposed to a cosmetic or dietary supplement product, which is what is out there now."

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