Henry Lahore is a retired engineer that found out about vitamin D in 2009. Like me he likes to help people. He has been busy reading the research and has created vitamin D Wiki. Here is his hypothesis on how our life styles have created disease states from vitamin D deficiency.
There is much information to be found at his Vitamin D Wiki site: http://www.VitaminDWiki.com
Vitamin D Deficiency Survivor 
Mark and Friends – Henry Lahore’s Vitamin D Wiki is an incredible resource with about 1000 articles, graphs, discussions, videos, book reviews, etc. I’d like to draw your attention to the very first link: “Vitamin D is not snake oil”. If you click the link you will see a graphic that shows many topics in alternative health sorted by both validity and interest level. Vitamin D is at the very top of the list, signifying the most credible arguments, and it is one of the biggest circles signifying it is among the most published topics in both the medical literature and popular press. Spend time on the wiki; there’s a lot to learn about vitamin D.