Many people swear by the vitamin supplement as a way to guard against colds and flu—but are they right?
A study in the Journal of Leukocyte Biology from May 2012 found that insufficient vitamin D is linked to a deficiency in the body’s immune responses. This suggests that boosting vitamin D in winter, when natural levels drop from a lack of sunshine, could increase your resistance to viral infections.
A September 2012 study in the US journal Pediatrics also showed that the risk of respiratory infections was halved in Mongolian children—a group known to be prone to vitamin D deficiency—who took a daily supplement of 300 IU (international units).
But the latest research isn’t all positive. A study of 322 healthy adults at the University of Otago in New Zealand showed that supplementing vitamin D in adults who aren’t deficient may not result in fewer or less severe colds.
Whether or not you decide to take the tablets, what’s certain is that vitamin D has a powerfully beneficial effect on your immune system. So make sure you eat plenty of the foods that contain it—such as oily fish, eggs and fortified breakfast cereals.