This is a very cool study that found that trans women could improve the microflora in their neovaginas by taking lactobacilli orally.
Trans women might need to keep taking the lactobacilli pills to maintain the good microflora in their neovaginas.
Why would you want to do this?
Well in addition to other benefits, mostly for digestion, lactobacilli can help to treat bacterial infections in the vagina and it may help prevent urinary tract infections.
According to the authors of the study, many trans women don’t have enough lactobacilli in their neovagina.
“The microflora of male to female transsexual women is a complex symbiosis of aerobic and anaerobic species with a very limited number of lactobacilli. It has substantial similarity to the abnormal vaginal microflora characteristic of bacterial vaginosis (BV) [1,2]. Weyers et al. reported that, although transsexual women show serum oestradiol levels comparable to those of postmenopausal women taking oestrogen replacement therapy, their neovaginal environment does not support the growth of lactobacilli . In one study , only one of thirty transsexual women had neovaginal colonisation with lactobacilli. Another study of transsexual women, the same authors  found a neovaginal lactobacilli colonisation rate of 4%.”
In this study, the authors found a higher rate of neovaginal lactobacilli colonisation, however, everyone who took the lactobacilli improved their scores.
The study was a good, randomized test of whether or not the lactobacilli worked, using 60 trans women split into two groups (one taking the lactobacilli, one not).
The bottom line – Post-op trans women should talk to their doctors about whether they should take lactobacilli.
Their discussion of their results:
“The results of this prospective randomised controlled study show that oral administration of L. crispatus, L. rhamnosus, L. jensenii and L. gasseri significantly improved the neovaginal microflora and reduced the Nugent score in a group of transsexual women. Also, the microflora was significantly enriched with lactobacilli after oral supplementation compared to placebo. The combination of Lactobacillus spp. used in this study is the only one published as the physiologic mixture of female vaginal lactobacilli microflora . We used an innovative probiotic lactobacilli composition containing four of the most common lactobacilli isolated from the microflora of healthy women’s vaginas  for treatment of 7 days’ duration. Weyers et al. reported that colonisation of the neovagina of transsexual women with lactobacilli is minimal [1,2]. According to Nugent, an intermediate vaginal microflora is defined by a reduction and BV by an absence of lactobacilli with the presence of Gram negative bacteria in both cases . The small number of publications on the standard neovaginal microflora and the near lack of evidence of lactic acid bacteria in the transsexual genital tract area are a challenge for investigations in this population. While transsexual women have normal female anatomy, there is no uterus and no connection of the neovagina to the pelvic cavity, which is why the risk of pelvic inflammatory disease is low. We were therefore able to include all transsexual women without clinical signs of infection, including those with asymptomatic BV. To our knowledge, this is the first study to allow a direct assessment of the comparative effect of oral probiotic lactobacilli and placebo on BV.
The gastrointestinal tract plays an important role as a reservoir for the vaginal colonisation by Lactobacillusspp. ,  and . Both vaginal and oral applications of lactobacilli have been shown to improve the vaginal microflora of both pre- and post-menopausal women , ,  and . The results of this study indicate that oral lactobacilli have a similar effect on the neovaginal flora of transsexual women. Descriptive analyses of the difference in Nugent score showed a reduction of −0.18 in the intervention group and an increase of +0.92 in the control group.
We found a significant improvement in the Nugent score in 48.5% of women in the intervention group, compared with only 14.8% in the control group. Lactobacilli concentrations assessed by culture and real-time PCR were 5–6 times higher in the intervention than in the control group, with these differences being statistically significant.
The sample size calculation in this study was based on neovaginal lactobacilli colonization rates of up to 4% reported in the literature  and . In the present study, however, 30% of the women in both the intervention and control groups had a normal lactobacillus microflora (Nugent score ≤3). This was an unexpected finding contrasting with the current literature  and . Because oral lactobacillus supplementation cannot be expected to change a neovaginal microflora dominated by lactobacilli, this unexpectedly high proportion of women with a normal lactobacillus flora may have led to an underestimation of the treatment effect. We therefore carried out a subgroup analysis including only women with a baseline Nugent score above 4, corresponding to either an intermediate microflora or BV. Even then, after 7 days of treatment with oral lactobacilli, we found an improvement in the Nugent score in the intervention group and no change in the control group. The results of this subgroup analysis are comparable with the results of one of our earlier studies on the effect of lactobacilli on postmenopausal women, which showed an improvement in Nugent scores . In contrast to the previous study with a lactobacilli treatment duration of 14 days, however, the improvement in the current was already seen after 7 days of oral lactobacilli. The renewed increase of the Nugent score two weeks after the end of oral therapy indicates that extended oral probiotic therapy may be necessary to maintain a lactobacilli-dominated microbiota.
This study had several limitations. With a specific study group of male to female transsexual women and very limited number of patients visiting our clinic we could observe only a small sample size in our study. The therapy duration was limited to 7 days: we assume that longer treatment with probiotics could obtain a better outcome. Microbiology analyses of CFU’s and c/ml were presented only for presumptive lactobacilli. In the next step we will include other bacteria with similar colony characteristics, such as Gardnerella vaginalis and Atopobium vaginae to present more detailed data. This study is first to observe male to female transsexual women using probiotics and we are aware of our initial oversights.
In summary, this first study on the effect of oral probiotics on the neovaginal microflora of transsexual women found that oral administration of lactobacilli resulted in a significant improvement in the Nugent score and a change of the neovaginal microflora. These observations are consistent with previous results obtained in pre- and post-menopausal women. The increase of the Nugent score two weeks after the end of oral therapy provides a possible need for extended oral probiotic therapy for maintenance of a lactobacilli-dominated microbiota. In addition, this study shows that even asymptomatic BV may be improved to a normal microflora by 7 days of oral supplementation of lactobacilli.”
Ability of an orally administered lactobacilli preparation to improve the quality of the neovaginal microflora in male to female transsexual women by Ulrike Kaufmann, Konrad J. Domig, Christina I. Lippitsch, Manuel Kraler, Julian Marschalek, Wolfgang Kneifel, Herbert Kiss, Ljubomir Petricevic in European Journal of Obstetrics & Gynecology and Reproductive Biology, Volume 172, January 2014, Pages 102–105.