Thursday, May 7, 2009

Low vitamin D linked to female infections

By Stephen Daniells, 29-Apr-2009

Low vitamin D levels may increase the risk of bacterial vaginosis, a common vaginal infection linked to adverse pregnancy outcomes, suggests a new study from the US.

In a study with 469 women participating in a pregnancy cohort study, vitamin D levels below 20 nmol/L were associated with a 34 per cent increase in the prevalence of bacterial vaginosis compared to women with vitamin D levels over 80 nmol/L.

According to researchers led by Lisa Bodnar from the University of Pittsburgh Graduate School of Public Health a potential protective effect of vitamin D may be due to the vitamin’s influence on the immune system.

The findings are published online ahead of print in the Journal of Nutrition.

The study adds to an ever growing body of science supporting the benefits of maintaining healthy vitamin D levels.

In adults, it is said vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases. There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 diabetes.

The new study represents the first report linking vitamin D status with the incidence of bacterial vaginosis, according to PubMed.

Bacterial vaginosis (BV) is a highly prevalent vaginal infection that affects about 30 per cent of women between the ages of 14 and 49. It is caused by changes to the normal chemical and biological balance of the vaginal microflora.

While antibiotics are usually prescribed to treat the condition, there is evidence that probiotics may prevent the condition. Extensive research by Gregor Reid from the Canadian R&D Centre for Probiotics at the Lawson Health Research Institute, and The University of Western Ontario, led to the conclusion that the combination of two particular strains - GR-1 (Lactobacilli rhamnosus) and RC-14 (Lactobacilli reuteri) - provide the greatest benefit for the relief and prevention of bacterial vaginosis.

New data

Bodnar and her co-workers examined the pelvises of 469 pregnant women before week 16 of their pregnancy. Blood samples allowed for the quantification of serum levels of 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form.

According to the Journal of Nutrition, 41 per cent of all the women had BV, and 52 per cent were classed as vitamin D deficient, equivalent to 25(OH)D levels below 37.5 nmol/L.

Women with BV were found to have a lower average 25(OH)D levels (29.5 nmol/L) compared to women free of BV (40.1 nmol/L), said the researchers. Looking at the same issue from another angle, 57 per cent of women with low 25(OH)D levels lower than 20 nmol/L had BV, while BV was diagnosed in only 23 per cent of women with a 25(OH)D levels over 80 nmol/L.

“Compared with a serum 25(OH)D concentration of 75 nmol/L, there were 1.65-fold and 1.26-fold increases in the prevalence of BV associated with a serum 25(OH)D concentration of 20 and 50 nmol/L, respectively,” wrote the researchers.

“Vitamin D deficiency is associated with BV and may contribute to the strong racial disparity in the prevalence of BV,” they concluded.

The study does not prove causality, and further studies are required to add support to the observation that vitamin D levels may be associated with the incidence of bacterial vaginosis.

The details on D

Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive.

While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.

Source: Journal of Nutrition
Published online ahead of print, 8 April 2009, doi:10.3945/jn.108.103168
“Maternal Vitamin D Deficiency Is Associated with Bacterial Vaginosis in the First Trimester of Pregnancy”
Authors: L.M. Bodnar, M.A. Krohn, H.N. Simhan

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