In individuals with the lowest levels of serum 25-hydroxyvitamin D3 (25(OH)D3), the risk of contracting pneumonia was more than 2.5 times greater than participants with high vitamin D levels, according to new research.

Men and the elderly were at greatest risk. This result remained even after adjusting for the determinants of serum 25-hydroxyvitamin D3.

The serum vitamin D3 levels of 1,421 subjects were measured from blood samples and compared against reported cases of pneumonia in hospital records in the same set of subjects between 1998-2009.

Researchers discovered that, during the follow-up, those with serum vitamin D3 levels representing the lowest third were more than 2.5 times more likely to contract pneumonia than subjects with high vitamin D3 levels. Smoking constituted a significant risk factor for pneumonia and the risk of getting contracting pneumonia grew with age, and was greater in men than women.