Vitamin D has come up a few times here before, and it's understandably a big concern for raw foodists, who do not eat food that has been supplemented with D.
I certainly respect the opinions and expertise of the other contributors, but I feel that D supplementation is being oversold without regard to what the consequences may be.
There's significant reason to believe that D supplements are not effective in preventing problems associated with D deficiency, and that they bring on additional medical problems themselves, as is often the case with vitamin supplements of many types as well as drugs and cures in general.
I think most people are unaware of just how much evidence against D supplements is out there, and that experts are starting to shy away from the supplement-happy suggestions they were issuing before.
There are hundreds of studies out there that would disagree with your belief that vitamin D supplementation isnt healthy.
Pretty predictable article, its all fine if you live somewhere where you get a decent summer to build up sufficent vitamin D stores given that your kidneys and liver covert fine. The UK is somewhat different are summer is full of rain and very little rays of sunshine and supplementation on a vegan diet or even SAD diet becomes necessary. Of course fat soluble vitamins present toxicity if used in the excess but take them at normal dosages they will prevent deficiencies and as many studies have shown reduce the risk of many diseases and ailments associated with vitamin D deficiency.
Getting sunshine is obviously much better, but I think supplement vs deficiency is debatable(in general, not just in this case). More research and studies are needed before I'd say steer clear. Personally I'll probably sup a bit this winter, but that's me.