Evidence suggests vitamin D pills help against colds and flu

Taking vitamin D supplements will reduce your risk of getting the common cold or a similar infection, according to research published by the British Medical Journal.

Researchers from Queen Mary University of London examined data from almost 11,000 patients worldwide. They looked at the effects of vitamin D intake on acute respiratory illnesses, including bronchitis, pneumonia and the common cold, a group of infections that account for about 300,000 hospital admissions each year.

Daily vitamin D supplements were found to reduce the odds of acute respiratory tract infection by 12 per cent, and in people with the lowest natural levels of the vitamin by 50 per cent.

In absolute terms, the proportion of people suffering at least one acute respiratory tract infection was reduced from 42 per cent to 40 per cent.

The researchers say that previous studies — which failed to link vitamin D consumption with respiratory infections — were inconclusive because the dose was administered monthly, which is now believed to be ineffective.

Professor Adrian Martineau, the study’s lead author, said: ‘This major collaborative research effort has yielded the first definitive evidence that vitamin D really does protect against respiratory infections.

‘By demonstrating this new benefit of vitamin D, our study strengthens the case for introducing food fortification to improve vitamin D levels in countries such as the UK where profound vitamin D deficiency is common.’

Our primary source of vitamin D is sunlight on the skin, though it can be obtained through a few foods, such as oily fish and fortified dairy products.

Instant analysis
This study analyses data from 10,933 participants across 25 randomised controlled trials. The main take-home finding is a reduction in acute respiratory tract infections (colds, chest infections etc) among those taking vitamin D supplements. The study concluded that, statistically, 33 people would need to be taking vitamin D supplements before one such infection would be prevented among that group.

This may not seem particularly exciting when explained in these terms, and for many drugs which may have significant adverse effects or safety concerns this would not be enough, but for a safe treatment such as this it could be considered significant.

The effect was shown to be greatest in those people with the most significant vitamin D deficiencies; and it could be argued that these people would already have reason to be taking vitamin D regardless of this study.

There has been growing momentum on vitamin D recently, with more and more people recommending vitamin D supplementation. What now needs to be decided is whether the vitamin should be added to common foods such as milk and bread.
MB
Research score: 4/5


  • M.Robinson

    Based on the experience of my daughter, who has been taking vitamin D supplements for years, I have my doubts about these findings. She has had more cold and flu-like illnesses than the rest of the family put together, including my three young grandchildren with their immature immune systems. A sample of one, I know, but we all have to speak from our own experiences, don’t we?

    • You seem to be aware of the danger of forming conclusions from anecdotes, but do it anyway.