If everyone took vitamin D supplements, more than 3 million fewer people in the UK would have respiratory infections like colds or flu every year. That’s according to a new analysis of data from nearly 11,000 people.
Vitamin D is known to be important for bone and muscle health. Last year, Public Health England stated that people are not generally getting the recommended 10 micrograms of vitamin D a day from sunlight in winter. But whether vitamin D supplements can help has been a hot topic, with some arguing that benefits of taking these are uncertain.
The latest study pulled together data from 25 clinical trials, conducted in 14 countries. It concluded that supplements can help prevent acute respiratory tract infections, particularly among those who are deficient in vitamin D.
The most common respiratory tract infection is the common cold, but others include bronchitis, pneumonia, and infections of the sinuses or ears. At least 70 per cent of the population gets one or more respiratory infection in any given year.
But the study found that vitamin D supplements can cut the proportion of people getting such infections by 12 per cent. “Daily or weekly vitamin D supplements will mean 3.25 million fewer people would get at least one acute respiratory infection a year,” says Adrian Martineau, at Queen Mary, University of London, who led the study.
Balancing the evidence
So should we all start taking supplements? “The bottom line is that the protective effects of vitamin D supplementation are strongest in those who have the lowest vitamin D levels and when supplementation is given daily or weekly, rather than in more widely spaced doses,” says Martineau.
He suggests that his team’s study strengthens the case for fortifying foods in the UK with vitamin D. However, others have argued that there is still not enough evidence that vitamin D supplementation prevents disease, except in people who are at high risk of the bone condition osteomalacia.
“We recommend that certain population groups take a daily 10 micrograms vitamin D supplement year round and everyone considers taking one during autumn and winter months to protect musculoskeletal health,” says Louis Levy, at Public Health England.
However, Levy says that the evidence on vitamin D and infections is inconsistent. “This study does not provide sufficient evidence to support recommending vitamin D for reducing the risk of respiratory tract infections.”
Journal reference: BMJ, DOI: 10.1136/bmj.i6583
By New Scientist staff and Press Association
15 February 2017