Vitamin D can improve the immune system's ability to fight infections.
High doses of vitamin D are likely to reduce the incidence of acute respiratory illness in older adults, suggests a study led by an Indian-origin researcher.
The study found that among those who took higher doses of vitamin D, there was a 40 per cent reduction in acute respiratory illness -- one of the leading causes of serious illness, debilitation and death among patients in nursing homes and other long-term care facilities.
"Vitamin D can improve the immune system's ability to fight infections because it bolsters the first line of defense of the immune system," said lead author Adit Ginde, professor at the University of Colorado, Denver, US.
"This is a potentially life-saving discovery. There is very little in a doctor's arsenal to battle ARI, especially since most are viral infections where antibiotics don't work. But vitamin D seems able to potentially prevent these infections," Ginde added.
In older people that first line of defence is often impaired. But vitamin D can reinforce it and prevent illnesses like pneumonia, influenza and bronchitis, Ginde said.
It may also prevent infections and exacerbations of chronic obstructive pulmonary disease (COPD) like emphysema.
Conversely, Ginde found that those who received higher doses of vitamin D also saw an increase in falls.
The falls were lower in those given smaller doses rather than higher monthly doses of vitamin D.
For the study, the team looked at 107 patients with an average age of 84 over a 12 month period.
Those who received higher doses saw acute respiratory illness cut nearly in half, but also had over double the incidence of falls, the study said.
The study was published in the Journal of the American Geriatrics Society.