There’s preliminary evidence that adequate amounts of vitamin D might help lower rates of respiratory infections.
These infections include colds, bronchitis and pneumonia, the researchers said.
In a review of past trials of people taking vitamin D supplements, researchers from Queen Mary University in London found that supplementation was linked to a 12 percent reduction in the proportion of people having an “acute respiratory infection.”
The researchers said their findings “support the introduction of public health measures such as food fortification to improve vitamin D status in settings where profound vitamin D deficiency is common.”
But not everyone agrees with the authors of the review, which was published Feb. 15 in the BMJ.
The results are inconclusive and need to be confirmed in carefully controlled clinical trials, said Mark Bolland from the University of Auckland in New Zealand and Alison Avenell from the University of Aberdeen in Scotland. They wrote their comments in an accompanying editorial in the journal.
“Current evidence does not support the use of vitamin D supplementation to prevent disease, except for those at high risk of osteomalacia [weak bones and muscles due to low blood vitamin D levels],” Bolland and Avenell wrote.
The study team was led by Adrian Martineau, from the Centre for Primary Care and Public Health at Queen Mary. The researchers reviewed data from 25 studies of vitamin D supplementation. More than 11,000 adults and children participated in the studies.
The review found an association between taking vitamin D supplements and a decreased likelihood of having a respiratory infection, but not a cause-and-effect link.
The 12 percent reduction meant that 33 people would need to take vitamin D supplements to prevent one acute respiratory tract infection. The benefit of the supplements was greater among people who took daily or weekly vitamin D without additional large doses, the study found.
The protective effect of vitamin D supplements was strongest for those with severe vitamin D deficiency. In this group, only four people would need to take vitamin D supplements to prevent one acute respiratory infection, the researchers said.
The Harvard School of Public Health has more on vitamin D.