When we think of a nutrient to fight colds and flu, most of us would think of vitamin C first.
And while this compound is vital and tremendously important for the immune system, the next letter of the alphabet deserves the same respect. Vitamin D is an intrinsic and essential driver for the immune system.
Vitamin D is a pre-hormone that made by the skin that is converted to another form by the liver and then its final form by other cells throughout the body into a steroid hormone.
Vitamin D in all its forms modulates the immune system; it stimulates antimicrobial proteins and killer cells and reduces inflammation. The immune effects of this substance are far-reaching, destroying cancer cells and supporting brain function.
Studies into how vitamin D behaves in the body have led to the knowledge that it can prevent colds, influenza, and other viral infections, especially those that affect the respiratory system.
A 2006 study found that children exposed to sunshine to produce adequate levels of vitamin D were much less susceptible to an outbreak of flu. (1)
A 2010 study supported this finding, with the number of children contracting the flu reduced by half if they took vitamin D supplements in the winter, when flu is more common.
An important subset of the study was children with asthma: two children who had taken vitamin D experienced attacks concurrent with the flu whereas twelve children who hadn’t taken vitamin D suffered asthma attacks. (2)