Lack of vitamin D may be linked to bacterial vaginosis during pregnancy

In April this year I discussed the evidence that probiotics may be helpful in the treatment and prevention of bacterial vaginosis.  Vaginosis usually involves a disruption in the normal bacterial and yeast balance in the vagina and is characterized by increased vaginal discharge (which is often odorous) without inflammation, sometimes there will also be itching present.

Normally a healthy vagina contains ‘friendly’ or beneficial bacteria, which protect it from invading pathogens (detrimental bacteria) such as those which cause urinary tract infections, thrush and vaginosis.  A healthy digestive system will also be dominated by a variety of different friendly bacteria.  If the vagina and digestive system are mainly colonised with ‘good’ bacteria these provide a barrier to the entry of pathogenic/harmful bacteria into the vagina.  Having a strong and healthy immune system protects the body from many bacterial infections and personal hygiene is also important to protect against vaginal infections (bacteria from the anal area may enter the vagina during sex or when wiping after a bowel movement).

Bacterial vaginosis is common in pregnant women and can put a woman at increased risk for a variety of complications, such as premature delivery.  There is great interest in understanding how vaginosis can be prevented.  Prebiotic and probiotic oral supplements or probiotic vaginal creams and suppositories may be helpful and are generally safe during pregnancy (but always check with your doctor, heath professional or midwife before deciding to try any treatment during pregnancy).  Recently (1) a study has found that vitamin D may also be playing a role.

Readers of my blog will know that Vitamin D has been very widely researched over the last few years and the importance of this sunshine vitamin for various aspects of health is vast. Many people in the UK often do not achieve good levels of vitamin D and this may be putting them at increased risk of various health problems.  A lack of this crucial nutrient has now been linked to heart problems, cancer, brain disorders, sleep problems, headaches, weight problems and immune problems to name but a few.  Vitamin D may play a protective role against vaginosis since it has quite an influence on the immune system.

The current study(1) looked to assess whether poor vitamin D status played a role in predisposing pregnant women to bacterial vaginosis.  469 pregnant women were included in the research.  The study investigated the relationship between vitamin D status and bacterial vaginosis in 209 white and 260 black women at less than 16 weeks of pregnancy with singleton gestations. Blood samples were taken, and blood serum was analysed to ascertain the levels of vitamin D.   Pelvic examinations were performed, and vaginal smears were used to assessed and diagnose rates of bacterial vaginosis.  The reason why skin colour may be an issue is that individuals with darker skin tones find it more difficult to manufacture vitamin D since less UV light can pass (3-36% in darker skins).  Pale skins allow more UV light to pass (53-72%) and make vitamin D manufacture easier.

The data indicate that overall, women with bacterial vaginosis had lower serum vitamin D levels than those without bacterial vaginosis. The prevalence of bacterial vaginosis decreased as vitamin D concentration in the blood increased.  The findings suggest that vitamin D insufficiency is associated with bacterial vaginosis in the first 4 months of pregnancy. Further, poor vitamin D status also seemed to contribute to the strong racial disparity in the prevalence of bacterial vaginosis.  This study only provides an idea, or hypothesis, for a link between vitamin D levels and rates of bacterial vaginosis.  Further controlled intervention trials will be needed to provide confirmation.

Foods rich in vitamin D are limited, with oily fish such as mackerel, salmon and sardines being the primary natural source.  Egg yolks also contain limited amounts of the vitamin and some breakfast cereals are fortified with the vitamin.  The exposure of our skin to sunlight is definitely the main source of vitamin D.  Recently, however, there has been mass debate about whether UV exposure in the UK is sufficient to keep vitamin D levels optimal for health.  Most individuals in the UK are falling short of recommended levels. 

If you rarely get out into the sunlight you may wish to consider a vitamin D supplement which provides around 12mcg of the nutrient per day (around 500iu).  Pregnant women are advised to check with their doctor, health professional or midwife before starting any supplement regimen.  Vitamin D supplements may be particularly useful during the autumn and winter months and for individuals who have darker skins or who don’t go outside regularly.

(1)Bodnar L et al.  2009.  Maternal vitamin D deficiency is associated with bacterial vaginosis in the first trimester of pregnancy.  J Nutr.  (April 8, 2009). doi:10.3945/jn.108.103168
Written by Ani Kowal