Julie - The research study you cite above is very suspect IMHO. I believe the authors are proponents of The Marshall Protocol. Please google it. As I understand it, they believe Vitamin D3 is harmful. Furthermore, I believe the first author listed is an RN and that none of them are M.D.s or Ph.D.s I find their promotion of drugs over Vitamin D troubling. Frankly, I have no idea how they managed to get into Pubmed. I did not research the reputation of that particular journal but I have doubts about it.
BTW Dr. Marshall himself is not a Medical Doctor but has a PhD in biomedical engineering. He believes that Vitamin D is immunosuppressive and that pulsed doses of antibiotics are curative. I think his position is seriously flawed and dangerous.
I know that Dr. Mercola is merely a chiropractor and derives profit from selling fear and supplements but I do think his review of The Marshall Protocol is worth reading - http://articles.mercola.com/sites/artic ... tocol.aspx