People who boost their vitamin D levels with supplements reduce their risk of respiratory tract infections, such as the flu, by up to 12%, according to a new systematic review and meta-analysis study of 25 randomised controlled trial (RCT) studies published recently in the British Medical Journal (BMJ).
The study reported that this equates to one person being spared a respiratory tract infection (RTI) for every 33 taking vitamin D supplements. The benefit is greater in those receiving daily or weekly vitamin D versus bolus or monthly dosing, with the number needed to treat dropping to 20. The impact in Canada, based on a population of 35 million people, shows vitamin D could spare 1.75 million people having one RTI per year.
“The results are likely to change the cost/benefit analysis relating to fortification of foods with vitamin D significantly,” said Adrian Martineau, clinical professor of respiratory infection and immunity at Queen Mary University of London.
This new study found:
• 12% reduction of respiratory tract infections based on all studies and all dosing regimens
• 19% reduction of respiratory tract infections for those receiving daily or weekly vitamin D doses
• No statistically significant effect on risk of respiratory tract infections for those receiving bolus or monthly dosing
• 70% reduction in respiratory tract infections for those with low vitamin D blood levels below 25 nmol/L and receiving weekly or daily dosing of vitamin D
In Canada, 35% of people or approximately 12 million people have vitamin D levels below 50 nmol/L. This increases to 40% in winter. More than 50 vitamin D scientists recommend that you reach a vitamin D blood level of between 100-150 nmol/L for optimal health.
“This study proves that by increasing your vitamin D blood levels through daily intake you could significantly prevent flu, colds and other respiratory infections,” said Perry Holman, Executive Director of the Vitamin D Society. “One of the reasons we have more flu and colds in the winter is due to the lack of UVB sun exposure and the resulting lower vitamin D levels.”