Vitamin D supplementation effective in preventing acute respiratory tract infections
Studies have consistently shown low levels of vitamin D will leave people more susceptible to respiratory infections
Studies have consistently shown low levels of vitamin D will leave people more susceptible to respiratory infections.
Acute respiratory infections are a major cause of ill health and mortality. Observational studies have consistently shown that people with low levels of 25-hydroxyvitamin D, the major circulating vitamin D metabolite, are more susceptible to respiratory infection.
Vitamin D supports the development of antimicrobial peptides in response to viral and bacterial stimuli. This may be the mechanism by which it provides protection against infection.
This study combined data from 23 randomised, double-blind, placebo-controlled trials of supplementation with vitamin D. It found that daily or weekly supplementation protected against acute respiratory infection whereas large bolus doses did not.
The ineffectiveness of bolus doses of vitamin D may be related to fluctuating levels of 25-hydroxyvitamin unbalancing the enzyme responsible for the breakdown of vitamin D in the body in a way that regular smaller doses do not.
Among those receiving daily or weekly doses, the benefits were greatest for those with profound vitamin D deficiency at base line but those with higher 25-hydroxyvitamin D concentrations also experienced benefit.
In summary, the researchers say that daily or weekly supplementation with vitamin D is safe, without any significant adverse reaction and is effective in protecting against acute respiratory infection.
They believe their findings support the introduction of public health measures such as adding vitamin D to food.
Martineau A, Jolliffe D, Hooper R et al (2017) Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 356:i6583. doi:10.1136/bmj.i6583.