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Taking vitamin D supplements regularly in winter could help fight off respiratory infections, a study has found.
The research was carried out on 164 male military recruits who either took 400 international units (IU) of vitamin D or an inactive placebo every day for six months from October to March.
Dr Ilkka Laaksi, from the University of Tampere, Finland, was the lead researcher and said the winter period is when most people’s vitamin D stores typically decline – due to a lack of exposure to sunlight – and when respiratory infections typically peak.
After the six months, no obvious difference was found between the two groups in the average number of days missed from duty due to a respiratory infection.
However, men in the vitamin D group were more likely not to have missed a single day of work due to a respiratory illness.
Overall, 51% remained “healthy” throughout the six-month study, with just 36% of the placebo group staying illness free, the study found.
Dr Laaksi said the results offer “some evidence” of a benefit of vitamin D against respiratory infections.
This backs up previous research that found people with relatively lower vitamin D levels in their blood tend to have higher rates of respiratory infections than those with higher levels of the vitamin.
However, Dr Lakksi said: “There is a lack of clinical studies of the effect of vitamin D supplementation for preventing respiratory infections”.
He added that larger clinical trials, looking at different doses of vitamin D, are needed before the vitamin can be recommended for cutting the risk of respiratory infections.
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