Probiotics is a collective term for microorganisms — more precisely acidic bacteria found in fermented dairy products and fermented veggies such as kimchi and sauerkraut — that are believed to be beneficial to the body, especially the bacterial flora of the digestive system. The concept that probiotics are good for you dates back to the early 1900s when it was first proposed that eating fermented yogurt enhances longevity, thanks to its lactic acid bacteria (lactobacillus). Today, probiotic supplements and food products have grown into a $40 billion market.
Most supplements target the digestive system and promise that an improved gut flora will benefit the body in general. But probiotics also are branded as effective against everything from allergies and high cholesterol to asthma and urinary tract infections (UTIs). However, the scientific evidence to support these claims to-date is thin. They haven’t been conclusively disproven either, but there just isn’t any proof that probiotics are very effective against these illnesses. The only ailment where research has shown that probiotics appear to clearly bring some relief are various forms of diarrhea.
However, probiotics don’t appear to have side effects, either. There are a few rare digestive and immunological issues, but overall probiotics are safe to take, even for children. That’s at least the current scientific consensus. Overall, the highly complex interactions of probiotics with the vast bacteria ecosystem in your gut and other organs is still poorly understood.
This question is still hotly debated in the medical community. There’s a number of small-scale studies that suggest that probiotics can help cure BV and stop it from recurring, but even the authors often concede that larger clinical trials are required. This is because bacteria in laboratory petri dishes behave different from when they are inside your body.
Treating BV with probiotics in theory makes sense, because BV is caused by an imbalance of bacteria in your vagina in the first place. Bad bacteria is growing faster and is colonizing more space than the good bacteria (like the lactobacillus genus). So, by introducing more lactobacillus into your vagina you are helping that good bacteria to gain the upper hand again and restore equilibrium. You can directly insert the probiotics into the vagina as suppository capsules or natural yohurt cultures. Another, less effective way is to take oral probiotic supplements — less effective, because the bacteria will have to traverse your entire digestive system, depart from the anus and migrate across the dam to your vagina. Direct vaginal application seems like the faster and better route.
So much for the theory. In reality, however, the specific lactobacillus types in most probiotics are L. rhamnosus and L. acidophilus, because these are the most common species in your digestive tract. In the vagina, however, L. crispatus and L. iners run the show and it’s them who lead the good fight against bad bacteria. Another problem is that probiotics, like most supplements, aren’t regulated by the FDA or anybody else. So, nobody checks whether they really contain what they promise on the packing and — as independent tests have found — often they don’t or at least not in the promised quantities.
However, there’s hope for women troubled by recurring BV: a vaginal L. crispatus medication is currently developed and in the last stages of clinical trials. It’s called Lactin-V and, if approved by the FDA, may soon become available to treat BV and help preventing it from recurring. Another future option that’s currently been worked on is vaginal microbiota transplantation, which means good bacteria are transplanted from another woman’s healthy vagina.
The story here is very similar to BV. Yeast infections are caused by uncontrolled growth of a vaginal fungus (candida albicans) because good bacteria can no longer counterbalance the fungus. This can happen when these bacteria are reduced in number by antibiotics or out-of-control diabetes. So, the probiotic treatment logic is the same as with BV: introduce more good bacteria to your vagina.
The research record on this is mixed, as studies tend to be small in size and typically women take probiotics while also taking conventional antifungal medication. It’s not clear how much of the healing process was contributed by the probiotics. Moreover, the same problems that apply to BV treatment also apply to yeast infections, i.e., getting the right species of lactobacillus.
However, since there aren’t any side effects, you can give it a try. Avoid oral probiotics and use vaginal applications (suppositories or live yogurt) instead as they should be more effective.
UTIs are more difficult to treat than BV and yeast infections, as the bacteria sit deeper inside the body — in your urethra and bladder, and in rare extreme cases even the kidneys (in the latter case only antibiotics help). External probiotic applications to the outer vagina will be of little use. There’s also no good evidence that oral probiotics can cure or prevent UTIs. There have been several studies over the past 20 years, but they often are of poor scientific value and show conflicting results.
Even when study results are positive, the suggested benefit of probiotics is limited. For example, one 2019 study that looked at 181 pediatric UTI cases found that taking probiotic supplements for 18 months cured about 15% more cases than were cured in a group of placebos.
But, again, the current scientific consensus doesn’t see much harm in taking probiotics either. So, oral probiotics can be tried as a first defense for an early-stage UTI with mild symptoms. Probiotics also can be used to complement other medication when treating a more advanced UTI.