Vitamin D and bacterial vaginosis (BV)

Researchers are looking into vitamin D and its impact on bacterial vaginosis (BV), particularly as a risk factor during pregnancy.

Results suggest that vitamin D can be very useful when used for asymptomatic BV, but is not directly useful for curing recurrent/chronic BV. This doesn’t mean vitamin D is not useful – it turns out it is very useful.

Vitamin D deficiency has been dentified as an independent risk factor for BV in pregnant women.

IMPORTANT NOTE: We think you should take vitamin D supplements while fighting BV! Vitamin D clearly has something helpful to offer in the war against BV and is inexpensive, inoffensive and non-toxic.

Dark skin, melanin and vitamin D

Additionally, those of African descent saw a reduction in BV incidence – at least during pregnancy, in one study – by taking vitamin D supplements.

The darker your skin, the more melanin it contains. Melanin is your natural sunblock but also blocks the process that results in vitamin D being produced by a chemical reaction in your skin.

Vitamin D deficiency is associated with BV, but the exact nature of this association remains to be determined with just a few studies completed so far.

How vitamin D may work in BV

Vitamin D is an important regulator of your immune response. Low vitamin D levels is associated with susceptibility to infections.

When vitamin D attaches to its receptor sites, the transcription of hundreds of genes occurs, including some that belong to the innate immune system.

Additionally, vitamin D increases the expression of cathelicidin – a protein active in destroying bacteria. Researchers have postulated that BV may be a result of vitamin D deficiency. While the research results are very interesting, the evidence has not confirmed this hypothesis.

Luckily, there are many researchers on the case and plenty of evidence to suggest that you should be taking vitamin D when treating any vaginal microflora infection or imbalance.

How to take vitamin D if you have BV

The first study looked at asymptomatic BV and vitamin D, and used 2,000IU as an oral supplement daily for 15 weeks. That’s a three-month treatment period.

You can take up to 10,000IU per day safely in an ongoing fashion, but a good dose is 4,000IU-5,000IU per day.

It can be useful to determine your vitamin D levels before supplementation with a simple blood test with your doctor. Some of you, especially those with light skin that get a lot of sun, will have good vitamin D levels, but if you have dark skin/wear a lot of sunscreen/never see the light of day, you may find that you are still deficient.

Vitamin D is synthesised in the skin during ultra-violet (UV) light exposure, but dark skin tones and sunscreen completely or partially block these rays and therefore the process of vitamin D synthesis can’t occur.

How much vitamin D is enough?

There is a debate raging about vitamin D deficiency, and at what level one should be considered ‘deficient’. We’re going to ignore the bottom rung number here because you want to aim for high vitamin D levels. Forget just having enough: you want plenty, for lots of reasons including bone health and immunity.

Generally, you are considered vitamin D deficient if your blood has less than 20ng/ml of 25-hydroxyvitamin D present​1​.

You want to aim for high levels of vitamin D, so over 50ng/ml or more. Getting to 150ng/ml is fantastic, and would require something like 4,000IU of supplementation per day.

Study #1 – vitamin D deficient women with asymptomatic BV – good cure rate

Researchers screened 218 women with asymptomatic BV for vitamin D deficiency (30ng/ml or less in a blood test), with 211 women (97 per cent) considered vitamin D deficient. These women were enrolled in the study.

The women were divided into two groups, one of which would receive a placebo, while the other received 2,000IU of vitamin D per day for 15 weeks. The placebo group received two drops of sesame oil daily.

At 15 weeks, vitamin D status was reviewed and the Nugent score determined whether asymptomatic BV had been cured.

Results of the study include:

  • The cure rate of asymptomatic BV in the vitamin D group was 64.5 per cent and 19.2 per cent in the placebo group
  • Vitamin D levels increased from an average of 9.4 ng/ml to 28.4 ng/ml in the vitamin D group
  • Vitamin D levels increased from an average of 8.9 ng/m to 9.3 ng/ml in the placebo group
  • Marital status, menstrual phase, and smoking all had significant relationships with BV, however, once these were accounted for, the placebo group was 10.8 times more likely to still have BV at the end of the study

Study #2 – High dose vitamin D in women with recurrent, symptomatic BV – didn’t make any difference

At a sexually transmitted disease clinic, 118 women were put on high-dose vitamin D supplementation (nine doses of 50,000IU over 24 weeks) to see if it made a difference in the recurrence rates of BV, while also being treated with oral metronidazole twice daily for a week.

While vitamin D significantly increased vitamin D levels, it did not reduce recurrence rates of BV.

Key findings of the study include:

  • Women receiving the vitamin D were just as likely as those in the control group, who did not receive the vitamin D, to have recurrences of BV at the end of the fourth and twelfth-week visits
  • In a strange twist, at the end of the 24 weeks, 65 per cent of those receiving vitamin D were likely to have BV, while just 48 per cent of those in the control group did
  • Short-term, high dose vitamin D supplementation did not decrease recurrent BV in women who were at high risk for STDs


Bouillon R, Van S, Gielen E, et al. Optimal vitamin D status: a critical analysis on the basis of evidence-based medicine. J Clin Endocrinol Metab. 2013;98(8):E1283-304.

Modarres M, Taheri M, Baheiraei A, Foroushani A, Nikmanesh B. Treatment of vitamin D deficiency is an effective method in the elimination of asymptomatic bacterial vaginosis: A placebo-controlled randomized clinical trial. Indian J Med Res. 2015:799. doi:10.4103/0971-5916.160707

Turner AN, Carr Reese P, Fields KS, et al. A blinded, randomized controlled trial of high-dose vitamin D supplementation to reduce recurrence of bacterial vaginosis. American Journal of Obstetrics and Gynecology. November 2014:479.e1-479.e13. doi:10.1016/j.ajog.2014.06.023

Am J Obstet Gynecol. 2011 Jan;204(1):41.e1-9. doi: 10.1016/j.ajog.2010.08.013. Epub 2010 Oct 8. Pregnancy-specific association of vitamin D deficiency and bacterial vaginosis. Hensel KJ, Randis TM, Gelber SE, Ratner AJ.

Powell AM, Shary JR, Louden C, Ramakrishnan V, Eckard AR, Wagner CL. Association of Bacterial Vaginosis with Vitamin D in Pregnancy: Secondary Analysis from the Kellogg Pregnancy Study. AJP Rep. 2019;9(3):e226–e234. doi:10.1055/s-0039-1693163

Jefferson, K.K., Parikh, H.I., Garcia, E.M. et al. Relationship between vitamin D status and the vaginal microbiome during pregnancy. J Perinatol39, 824–836 (2019) doi:10.1038/s41372-019-0343-8

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Jessica Lloyd - Vulvovaginal Specialist Naturopathic Practitioner, BHSc(N)

Jessica is a degree-qualified naturopath (BHSc) specialising in vulvovaginal health and disease, based in Melbourne, Australia.

Jessica is the owner and lead naturopath of My Vagina, and is a member of the:

  • International Society for the Study of Vulvovaginal Disease (ISSVD)
  • International Society for the Study of Women's Sexual Health (ISSWSH)
  • National Vulvodynia Association (NVA) Australia
  • New Zealand Vulvovaginal Society (ANZVS)
  • Australian Traditional Medicine Society (ATMS)