amandawood , You talk a lot of sense. I think the course of vitamin D research has some way to go before it can be said to have diverged from that on antioxidants. So far the rationale for supplementing vitamin D is the same as was the case for supplementing antioxidants, sick people have less. That is exactly what has been found for vitamin D levels, There is one big difference: the trials of vitamin D supplementation have not been done yet.

The main reason I am certain that extra 'D' is bad is the way the body treats it. It restricts the amount in the blood by various mechanisms. So I think you ought to be wondering whether your body's metabolism is so wrong to 'flush it down the toilet' (most of it anyway). To my way of thinking if it was beneficial vitamin D would be treated as such by the body - it isn't.

Low carb eating is natural , ingesting vitamin D year round in the unnaturally massive amounts required to raise serum levels - of just one metabolite - is getting away from what our bodies are designed for. Any time that route is taken there is a price to be paid.