>Vitamin D is already known to be safe if not taken at too high a dose.

There were some posts on here by a doctor that have seen problems with people who were inside the norm of D.vit. so I wouldn't trust the above. I have to take D vitamins because there's something wrong with me and doctors want to monitor my blood levels because of it. Calcium levels are one thing that can become too high with normal range d.vit. if taking supplements. Vitamin D supplement is medicine which most people seem to forget. Using medicine means seeing a doctor to make sure it is safe, at least a blood test every 6 months.

Edit: here's one of her threads: https://news.ycombinator.com/item?id=24138590