Vitamin C is commonly associated with immunity boosting, but recent research has suggested vitamin D may also have that effect.

A team of researchers from the University of Colorado at Denver and Massachusetts General Hospital in Boston analyzed blood samples from 19,000 U.S. adults who also underwent physical exams, according to a report by Ottawa Citizen.

They found that those with the lowest vitamin D blood levels – under 10 nanograms per milliliter of blood – were 40 percent more likely to report recent colds or flu than those with vitamin D levels above 30 nanograms.

The study appeared in the Archives of Internal Medicine.

The study comes on the heels of a report which has found that the average blood levels of vitamin D appear to have decreased in the U.S. between 1994 and 2004, and American teenagers are at a particular risk for the deficiency.

For that reason, the scientists who conducted the study recommend an intake of 1,000 IUD or more of vitamin D, especially during the winter months and at higher latitudes.

Additional doses of vitamin D may be obtained from nutritional supplements.