A respiratory tract infection is an infection in the nose, throat and lungs and includes colds, sinusitis, tonsillitis, laryngitis and pneumonia. If left untreated they can be a major cause of illness and even death, particularly in vulnerable populations like the elderly.

Interestingly, observational studies (studies which observe risk factors in populations) have shown a protective effect of vitamin D on respiratory infections. This has led to the hypothesis that vitamin D may assist in reducing the risk of acute respiratory tract infection.

Researchers analysed the available data to better understand an association between vitamin D supplementation and acute respiratory tract infection. All studies included in the analysis involved supplementation with vitamin D3 or vitamin D2 and incidence of both upper and lower acute respiratory tract infections.

The meta-analysis identified a reduction in incidence of acute respiratory tract infections association with vitamin D supplementation. This protective factor was particularly pronounced in people who had low levels of circulating vitamin D to start with.


Vitamin D has many benefits, one of which may be associated with reducing risk of acute respiratory tract infection. Vitamin D is also essential for strong bones, muscle and overall health. Sun is the best natural source of vitamin D, and you don’t need much exposure to keep your vitamin D levels up.

You should also be aware that vitamin testing is largely a waste of time and money and that the real benefits of vitamin D supplementation are probably less than people have thought in the past. If you think vitamin D supplements may be of benefit to you it’s important you talk to your doctor before commencing use.