1 in 7 men will develop prostate cancer. The preliminary research is still early, but Vitamin D was shown to shrink prostate cancer and in some cases, completely reverse it.
I have nothing but praise for Vitamin D. I highly recommend a blood test before adding Vitamin D - especially in high doses. AND ask your doctor for your results. Some doctors aren't up-to-date on optimal vitamin levels.
Vitamin D did require an adjustment period of about 3 weeks for me. I had an enormous burst of energy coupled with insomnia that lasted during this phase. It eventually settled and now I feel "normal" and sleep well. And the benefits, well for one: my skin - oh how soft it is! All the problems with dry skin - GONE! Yay! It also reduces anxiety - which is a nice mood enhancement.
I eventually worked up to 10,000 IU 5x per week. I work with my doctor on this and get blood tests regularly. I had actually cut back my dose after a family friend suggested I didn't need to take that much, and guess what? My levels fell back into the bad range again! So now I am happily staying at this dose until my blood tests indicate I need to reduce it.