A single 2.5 mg 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.

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 randomized controlled trial on a group of volunteers who were given either a 2.5 mg supplement of vitamin D or a placebo. Samples of the volunteers’ blood were then tested to see whether the vitamin D 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. According to the NIH website, 400 IU of vitamin D is equal to 10 micrograms of vitamin D; thus, the single 2.5 mg dose used in this study was equal to about 100,000 IU of vitamin D, which is about 100 times the 800 to 1000 IU minimum daily dose being recommended by some for optimum health. Vitamin D is stored in the body, and this one-time dose seemed to carry residual efficacy for at least six weeks.

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 (April 26, 2007).

Vitamin D was used to treat TB in the pre-antibiotic era, when special sanatoria were built in sunny locations (where skin exposure to the sun could increase vitamin D levels in the body), 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 such as vitamin D could be an important strategy for tackling tuberculosis and perhaps even antibiotic-resistant mycobacteria (Courtesy of Wellcome Trust).