More research evidence has surfaced indicating that large doses of vitamin D can kill flu virus, suggesting that if taken in the early stages of an infection, it may help to prevent the virus from becoming established.
http://www.ncbi.nlm.nih.gov/pubmed/23052388LL-37, the only human cathelicidin, is a cationic antimicrobial peptide with antibacterial and antifungal activity. LL-37 is released from neutrophil granules and produced by epithelial cells. It has been implicated in host defence against influenza A virus (IAV) in recent studies. We now demonstrate dose-related neutralizing activity of LL-37 against several seasonal and mouse-adapted IAV strains. The ability of LL-37 to inhibit these IAV strains resulted mainly from direct effects on the virus, since pre-incubation of virus with LL-37 was needed for optimal inhibition. LL-37 bound high-density lipoprotein (HDL), and pre-incubation of LL-37 with human serum or HDL reduced its antiviral activity.
The reason why this works is because vitamin D upregulates cathelicidin, which is a naturally occurring anti-microbial peptide in humans, and research shows that cathelicidin is active against the influenza virus.
http://blog.vitamindcouncil.org/2013/01 ... its-early/
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