High doses of vitamin D may not help prevent recurrence of bacterial vaginosis (BV), according to results of a randomized controlled trial.
In the double-blind trial, 118 women with symptomatic BV who had visited an urban sexually transmitted disease clinic received 500 mg of oral metronidazole for 7 days. Half were randomized to receive 9 doses of 50,000 IU of cholecalciferol (vitamin D3) over the course of 24 weeks and half received placebo. Nugent scoring after 4, 12, and 24 weeks was used to assess recurrent BV.
The majority of participants (74%) were black and the median age was 26 years. Median pre-supplementation serum levels of vitamin D were similar across both arms of the study: 16.6 ng/mL in the vitamin D arm and 15.8 ng/mL in the control arm. After the study ended, serum levels were 30.5 ng/mL in those receiving vitamin D, versus 17.8 ng/mL in controls. Of women in the vitamin D arm, 16% were vitamin D deficient (<20 ng/mL) versus 57% in the placebo arm.
Prevalence of BV was similar among women who received vitamin D and those on placebo at the 4- and 12-weeks visits. At the 24-week visit, prevalence of BV was 65% in the vitamin D group versus 48% in the control group. Median time to BV recurrence was 13.7 weeks in the vitamin D group and 14.3 weeks in the control group. Overall, recurrence of BV was not reduced with supplementation (intention-to-treat hazard ratio, 1.11; 95% confidence interval, 0.68–1.81).
Study limitations noted by the authors included its small size, lack of test of cure, and higher-than-expected loss to follow up at 24 weeks. A strength was the demonstrated rise in 25(OH)D in women randomized to vitamin D versus controls, which showed strong evidence of compliance. Their findings, the authors concluded, “suggest that short-term, high-dose vitamin D supplement does not reduce BV recurrence in nonpregnant women. Given the established associations between BV and negative health outcomes, effective interventions to reduce BV’s impact continue to be urgently needed.”
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