Vitamin D and Recurrent Bacterial Vaginosis

High-dose vitamin D supplementation did not decrease the recurrence of bacterial vaginosis (BV) among women at a high-risk sexually transmitted disease clinic.

A double-blinded study, which involved 118 women, found that while vitamin D supplements significantly increased serum 25-hydroxyvitamin D levels, supplementation did not reduce the recurrence of the common infection. By measuring the increase in serum 25-hydroxyvitamin D levels, the authors said they were able to determine compliance in taking the supplements.

Key Points:

- Short-term, high-dose vitamin D supplementation did not decrease the recurrence of bacterial vaginosis among women at high risk for STDs.

- Although the dose of vitamin D in the study was high, the threshold of serum 25-hydroxyvitamin D that was used in the study may not have been sufficient for a clinically meaningful effect.

The study was undertaken because low serum vitamin D levels have been associated with an increased prevalence of BV, which occurs when the "good" and "bad" bacteria in the vagina become unbalanced. Why some women are prone to this infection is unknown, but women with BV are more susceptible to sexually transmitted infections, particularly HIV. BV is also associated with obstetrical complications, according to background information provided in the study.

All the women were treated for BV with 500 mg of oral metronidazole twice daily for a week. In addition, 59 of the women also were given 9 doses of 50,000 IU of cholecalciferol (vitamin D₃) over 24 weeks. The women in the control group received a matching placebo. All women were assessed for recurrent BV at 4, 12, and 24 weeks.

The results found that women receiving vitamin D were just as likely as those who didn’t get the supplement to have recurrent BV at the 4 and 12 week visits. And while previous studies have linked vitamin D supplements with a reduction in BV, this study found that at 24 weeks, 65% of the women receiving the vitamin had BV while 48% of those in the control group had BV.

The study did not include tests to ensure the initial BV case was cured, so some of the reports of recurrent BV could have actually been a persistent infection that never resolved, the authors reported. “However, for a polymicrobial clinical syndrome such as BV, where the division between health and disease is a continuum rather than a sharp line, the distinction between prevalent and reemergent disease may be less important,” the authors wrote.

While serum 25-hydroxyvitamin D levels were raised, the authors suggested that their study couldn’t determine if the levels increased enough to make a clinical difference and that 30 ng/mL may not be a meaningful threshold for BV recurrence. A higher target level may be more appropriate and prove to have an impact on warding off BV, they suggested. However, there is considerable debate about the appropriate dose, schedule, and target serum 25-hydroxyvitamin D levels for optimal health, they noted.

The study was published in the American Journal of Obstetrics & Gynecology.