Several studies have shown that infants, children, and adults are at increased risk for influenza and other serious lower respiratory infections when their vitamin D levels decline. A recent 2009 study found that risk was 36 percent greater for healthy people with vitamin D levels below 30 ng/ml.
As soon as flu and cold viruses invade our bodies, the immune system releases virus-killing compounds called antimicrobial peptides (AMPs). Our lungs and bronchial passages are especially rich in AMP-producing cells. These cells require vitamin D to function effectively.
Vitamin D also balances inflammatory cytokine release. Cytokines are chemicals that are in part responsible for the fever and congestion associated with colds and flu. A hyper-reactive immune response, called "cytokine storm," has been linked to several fatal cases of influenza. Vitamin D not only enhances our ability to produce AMP molecules, but the "sunshine vitamin" also simultaneously balances the cytokine response that causes most of the misery during a bout of influenza.
For more information on vitamin D, as well as your individual nutritional requirements to maintain a healthy and strong immune system, please visit www.lef.org.