http://us63bgjkxwpyrpvsqom6kw3jcy2yujbplkhtzt64yykt42ne2ms7p4yd.onion
Everything you have ever wanted to know about Vitamin D - the most important nutrient for human biology - is here. And then ten times that, if you are still hungry :D. Beautifully presented and fully referenced, even includes a bunch of charts, graphs, etc for pretty much every relevant issue.