will vitamin d kill you?

The answer: maybe. Any supplement may help, may hurt. But the debate about the safe dosage of supplements is nicely examined in this CBC article. My doctor friend says a multivitamin is more than enough. Taking vitamin D, fish oils, zinc, and so on, are not really necessary, she says.

Of course, strong discussion is the key to sorting out a consensus: aren't toxicity levels where the harm outweighs the benefit? Read up here and here in the Boston Globe.

The biggest issue is the causality of vitamin D deficiency. Does disease cause a deficiency, or does the deficiency cause disease? Until this is definitively sorted out, taking vitamin D will be for most a matter of piece of mind.