New Scientist included a story this week of studies that have shown that supplementation with Calcium may not be a good idea if you're not clinically deficient.
newscientist.com/article/21...
They also refer to a previous study that showed people supplementing with Vitamins A, C and E and the mineral selenium (all supposed to be good for you as they're antioxidants) tend to die earlier than those not taking them as pills.
Two years ago NS did a very good summary of lots of supplements and how, barring medical conditions, most can be replaced by a balanced diet and are a waste of money. Others can actually be harmful.
The article Is for subscribers only. I'll try and précis it, when I get a working computer again.