"The non-financial costs such as side effects or potential adverse effects are practically non-existent as well."

This not accurate. I remember that there was an article on the front page of Hacker News an article that explain that Vitamin D is actually a hormone and telling the story of woman that had been prescribed high level of supplementation that could not talk anymore. It had something to do with her calcium intake regulated by that hormone. Luckily she was so distressed she stopped taking the supplementation but still it took her six months to get back to to talking normally and a normal hormone concentration level.

EDIT : I found the article : https://news.ycombinator.com/item?id=24261948