One of the hallmarks of a healthy vagina is low bacterial diversity, and high abundance of vaginal lactobacilli. Lactobacilli contributes to acidic vaginal pH, which plays a valuable role in vaginal health. The normal vaginal pH for women of reproductive age ranges from 3.8 to 5. A reduction in Lactobacilli increases vaginal pH, thus enabling pathogenic organisms to colonise the vagina.1,2,3
Infections, the use of certain medications (eg antibiotics, hormonal contraceptives) negative impact the VBM. Vaginal health can also be affected by menstrual cycles, as well as lifestyle and dietary factors.1
Infections: Bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) are two of the most common vaginal infections. BV is characterised by a decrease in lactobacilli and increase in atypical anaerobic bacteria. The infection increases the risk of sexually transmitted diseases, such as Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, herpes simplex virus type 2, human papillomavirus, and HIV. It is also a risk factor for other infections such as pelvic inflammatory disease, endometritis, chorioamnionitis, and amniotic fluid infection. Metronidazole and clindamycin are the first-line antibiotic regimens for BV. The short-term cure rates are about 80%, however 50% of women experience recurrence within six- to 12- months after use. Biofilm formation as well as antibiotic resistance of BV-associated bacteria may be the cause of recurrence. Antibiotic use also increase the risk of VCC co-infection, which require treatment with antifungals.1
Hormonal contraceptives: Women who do not use hormonal contraceptives and those who do use it, have similar menstrual cycle fluctuations (see below) and high Lactobacillus abundance. However, women who use progestin-only contraceptives showed altered periodic fluctuations of VMB and low average abundance of Lactobacilli.1
Menstrual cycles: Oestrogen fluctuations throughout menstrual cycle modulates VMB composition, affecting the ability of vaginal lactobacilli to colonise the vaginal tract and produce lactic acid.1
Lifestyle factors: Similar to the gut microbiota, different lifestyle factors influence VMB composition. Personal hygiene practices (eg vaginal douching, use of soaps, type of underwear, menstrual protection, and sprays) are the most direct ways to affect VMB composition. Research suggests that vaginal douching seems to be most strongly associated with increased risk of BV/vaginal dysbiosis. Multiple sexual partners are also a known risk factor for vaginal infections and lactobacilli depletion. Another risk factor is smoking.Smoking affects oestrogen production and alter vaginal metabolite production, particularly by increasing levels of nicotine and derivatives as well as biogenic amines. Similarly, alcohol use is associated with increased BV incidence.1
Diet: Diet does not only affect the gut microbiota, but also the vaginal tract. Research suggests that healthy diets rich in nutrients, with a low glycaemic index and lower fat intake could reduce the risk of BV. BV is also more common in women living with obesity compared to lean women. Furthermore, micronutrient intake, particularly increased folate, vitamin A, and calcium could decrease BV risk. In addition, diet rich in betaine is associated with higher vaginal Lactobacilli abundance. A small study showed that vaginal microbial diversity was higher among vegetarian compared to non-vegetarian women.1
How effective are probiotics promoting vaginal health?
Probiotics are commonly lactobacilli and their role in vaginal health has been extensively investigated. Increasing evidence show that specific probiotic strains or their combinations elevate vaginal lactobacilli counts in healthy women or women with BV and/or VVC and support natural VMB during/after recovery from antibiotics or antifungal treatment.1
More than two decades ago, Reid et al (2001) showed that treatment with oral lactobacillionce and twice daily resulted in healthy vaginal flora in up to 90% of patients and 63% of patients with BV converted to normal or intermediate scores within one month.4
In another study, Reid et al (2001) showed that treatment with probiotics twice daily for 14 days, resulted in the resolution of 60% of asymptomatic BV or intermediate BV within one week of therapy.5
Furthermore, probiotics have also been shown to be effective in the prevention of urinary tract infections (UTIs) in women. Reid et al (2017) do point out that for acute UTI, antibiotics are needed, but for BV, probiotics ‘could be a treatment per se’. It can be used on its own and not just following antibiotic therapy, especially given the many issues with antibiotics: poor efficacy, poor eradication of biofilms, destruction of commensal lactobacilli, antibiotic resistance induction, and various short- and long-term side effects.6
Furthermore, Kopicki et al showed that adding probiotics (typically Lactobacillus species) to antifungal therapy for VCC improves short-term cure rates by 14% and reduces one-month relapse rates by 66%.7
The use of probiotics can improve vaginal health by increasing beneficial bacteria, reducing the number of harmful bacteria, and maintaining the stability of the vaginal microbiome.