If we're going to call out one of those three vitamins for overdose potential, it's the magnesium you should be calling out, not the vitamin D. Accidental vitam

If we're going to call out one of those three vitamins for overdose potential, it's the magnesium you should be calling out, not the vitamin D. Accidental vitamin D overdose seems to be a non-issue, almost (but not quite) entirely theoretical. Clinically-significant doses of magnesium can have real effects on the body, though, even in the "safe range"; it affects your heart fairly strongly, for instance, and needs to be in balance with some other nutrients. Even if you are in fact in need of magnesium supplementation, you can trigger some heart issues if you supplement magnesium without the other nutrients you need to go with it. This won't happen to most people, but I'd guess it's a 3-4 more orders of magnitude serious concern than vitamin D overdose.