Why is Vitamin D significant?

If vitamin D is fat-soluble, why is so much of it included in daily multivitamins?

• This also goes for vitamin k, iron, and etcetera. I'm looking at the One A Day woman's multivitamin and see that it has 250% daily value(vitamin D). This would be an overdose, especially if this much is taken daily...correct? And why do multivitamins often contain 100% daily value of a majority of the vitamins included? Certainly, it's expected we will eat other food during the day and will not need the entire day's value...why don't most simply provide half? Or three-quarters?

• Answer:

  The RDA is the bare minimum required not the optimal amount & no where near the maximum amount. The RDA for vit. D was 400iu & raised to 600iu & researchers are in an uproar - most recommend 5000iu. Multivitamins do not include 100% of vitamins that can cause toxicity.