Vitamin D helps infection-prone patients avoid respiratory tract infection

Taken from the British Medical Journal (BMJ) – by Bruce Sylvester – High doses of vitamin D taken for a year appears to help infection-prone patients achieve a lower risk of respiratory tract infection, according to a study by researchers at Karolinska Institutet and Karolinska University Hospital in Stockholm, Sweden. The research was published on Dec. 13, 2012 in  BMJ Open.

“Our research can have important implications for patients with recurrent infections or a compromised immune defence, such as a lack of antibodies, and can also help to prevent the emerging resistance to antibiotics that come from overuse,” said Peter Bergman, MD, Ph.D, researcher at Karolinska Institutet’s Department of Laboratory Medicine and physician at Karolinska University Hospital’s Immunodeficiency Unit. “On the other hand, there doesn’t seem to be anything to support the idea that vitamin D would help otherwise healthy people with normal, temporary respiratory tract infections.”

As background, the authors noted that vitamin D is synthesized through exposure to sunlight and also found in certain foods. Prior research has shown that low levels of vitamin D can increase the risk of infection, and that vitamin D can also activate immune system defenses.

The investigators enrolled 140 subjects from the Immunodeficiency Unit at Karolinska University Hospital who had shown symptoms of disease in their respiratory tracts for at least 42 days prior to the study.

They randomized the subjects into two groups. One received vitamin D in high doses, the other received a placebo. Each subject kept a daily health diary for a year.

The investigators found that symptoms of respiratory tract infection declined by almost a quarter and the use of antibiotics by almost half in the vitamin D group. Vitamin D treatment was well tolerated,  and no serious side-effects appeared.

The investigators noted that the effect of vitamin D on respiratory tract infection is controversial. A  study published recently in JAMA found that vitamin D did not reduce the incidence or severity of viral respiratory tract infections. But, they said, the new study differs from the JAMA study. The JAMA study examined a group of healthy people with initially normal levels of vitamin D in the blood, and used bolus dose administration (large doses on fewer occasions), which is thought to be less effective that daily doses.

“However, the most important difference is probably due to the fact that our participants had much lower initial levels of vitamin D than those in the New Zealand study,” said Dr Anna-Carin Norlin, doctoral student and co-lead author of the study along with Dr Bergman. “There is evidence from previous studies that vitamin D supplements are only effective in patients who fall well below the recommended level, which also suggests that it would be wise to check the vitamin D levels of patients with recurrent infections.”

The study was financed by Karolinska Institutet, the Stockholm County Council and the Swedish Foundation for Strategic Research (SSF).