I am Count Iblis. My mission on this planet is to enlighten the primitive creatures living on this planet (a.k.a. humans) with my infinite knowledge. Unfortunately, I'm only allowed to give vague hints; at most I can communicate information that a very clever human could theoretically have come up with. I also post on my blog. The last post is already 2 years old, it is difficult for me to post more without violating the restriction I'm under.
Since figuring out vitamin D's real function seems to be too difficult for humans, I've given a few hints here. This is important, because you can then understand that the maximum dose you can get from the Sun, roughly 10,000 IU/day, is the dose you should get. This is a normal dose, not a "mega-dose". Even if you get 5,000 IU/day, you are still way below the dose at which your body functions optimally.