Yes, Rabbitears, I am convinced that Vitamin D is also a crucial piece to the immune puzzle. Especially in the US there is a huge deficiency of Vit. D again in the majority of the people. The Vit. D deficiency issue is also global. If you are not famaliar with the Vitamin D Council I strongly recommend you visit their website and sign up for the e-newsletter. It comes out quarterly I think. They search and research the research being done on Vit. D and report their finds every few months on what new has come out. It is an awesome site and newsletter.