The 'sunshine vitamin' as it known, not just improves bone and muscle health but also protects against respiratory infections by boosting levels of antimicrobial peptides — natural antibiotic-like substances — in the lungs.
Acute respiratory infections such as pneumonia are a major cause of global morbidity and mortality.
"Most people understand that Vitamin D is critical for bone and muscle health. Our analysis has found that it helps the body fight acute respiratory infection,...," said Carlos Camargo from the Massachusetts General Hospital (MGH).
The findings showed that daily or weekly supplementation halved the risk of acute respiratory infection in people with most significant Vitamin D deficiency — below 25 nanomoles per litre (nmol/L).
Administering occasional high doses of Vitamin D did not produce significant benefits.
People with higher baseline Vitamin D levels also benefited, although the effect was more modest (10 per cent risk reduction), the researchers noted, in the paper published in the journal BMJ.
"Our study strengthens the case for introducing food fortification to improve Vitamin D levels in countries where profound vitamin D deficiency is common," added lead researcher Adrian Martineau Professor at Queen Mary University of London (QMUL) in Australia.
For the study, the team analysed nearly 11,000 participants in 25 clinical trials conducted in 14 countries including India, Britain, US, Japan, Afghanistan, Belgium, Italy, Australia and Canada.