Vitamin D May Have Protective Role Against Respiratory Infections Interview with:
Dr. Adrian R Martineau
Clinical Professor of Respiratory Infection and Immunity
Centre for Primary Care and Public Health.
Blizard Institute, Barts and The London School of Medicine and Dentistry
Queen Mary, University of London What is the background for this study?

Response: In addition to its well-known effects on bone, Vitamin D has also been shown to boost immune responses to viruses and bacteria that cause respiratory infections in lab experiments.

In order to see whether these effects translate into a health benefit, a total of 25 clinical trials of vitamin D supplementation to prevent various respiratory infections have been carried out in around 11,000 people living in 14 different countries over the last decade.

These trials have yielded conflicting results: in some, vitamin D reduced the risk of infections, but in others it did not.

The reason why vitamin D ‘worked’ in some trials, but not in others, has been the subject of much debate.

In order to answer this question, we assembled an international consortium of investigators and compiled the raw data from every trial into a single database containing information from 10,933 people in total. This allowed us to run sub-group analyses to determine whether particular groups of people benefit more from vitamin D supplementation than others. What are the main findings?

Response: Overall we found that vitamin D supplementation reduced risk of acute respiratory infections by around 10%. However, protective effects were much stronger when vitamin D was taken by people who had the lowest vitamin D levels – they experienced a 50% reduction in risk of respiratory infection with vitamin D.

We also showed that vitamin D was more effective at preventing respiratory infections when it was given in daily or weekly doses, as opposed to doses that are more widely spread out. What should readers take away from your report?

Response: This is the strongest evidence yet that vitamin D supplementation has important health benefits for the immune system. Our study provides strong evidence that giving vitamin D supplements to people with low vitamin D levels decreases their risk of getting acute respiratory infections. What recommendations do you have for future research as a result of this study?

Response: Health economic analyses are needed to re-calculate the cost: benefit assessment for vitamin D supplementation in light of these new findings. Our findings support the rationale for fortifying foods with vitamin D in countries such as the UK where vitamin D deficiency is common.

No conflicts of interest to declare. Thank you for your contribution to the community.


Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual


Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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