A single 2.5mg dose of vitamin D may be enough to boost the immune system to fight against tuberculosis (TB) and similar bacteria for at least six weeks, researchers have found.

In a study published today, researchers from Queen Mary's School of Medicine and Dentistry, London, and the Wellcome Trust Centre for Research in Clinical Tropical Medicine, Imperial College London, identified an extraordinarily high incidence of vitamin D deficiency among those communities in London most at risk from the disease.

Over 90 per cent of patients at Newham University Hospital and Northwick Park Hospital in London with TB were found to have a vitamin D deficiency.

The researchers performed a randomised control trial on a group of volunteers who were given either a 2.5mg supplement or a placebo. Samples of the volunteers' blood were then tested in Dr Robert Wilkinson's Wellcome Trust-funded laboratory at Imperial College, to see whether the supplement affected the immune system's ability to withstand infection by mycobacteria.

A single large dose of vitamin D was found to be sufficient to enhance a person's immunity to the bacteria.

Vitamin D was used to treat TB in the pre-antibiotic era, when special sanatoria were built in sunny (vitamin D-rich) locations, such as the Swiss Alps. But until now, no study has evaluated the effect of vitamin D supplementation on immunity to mycobacteria, the family of bacteria that cause TB.

According to the Health Protection Agency, the incidence of TB in the UK is increasing, with around 8000 new cases a year. TB is also a major global problem. Nine million people a year develop the active disease worldwide, which kills two million each year.

Most cases of TB in London arise from people who have already become infected with the bacteria but in whom it lies latent. Identifying people with latent TB and providing supplements could be an important strategy for tackling the disease.

The research, funded by the Wellcome Trust, the Department of Environmental Health at Newham Council and Newham University Hospital NHS Trust Respiratory Research Fund, is published online in the American Journal of Respiratory and Critical Care Medicine.

External links

• Press release
• A Single Dose of Vitamin D Enhances Immunity to Mycobacteria by Martineau, A. et al, Am. J. Respir. Crit. Care Med. 2007