Here’s an interesting article on how much Vitamin D we actually need:

“For proper functioning, a healthy human body utilizes around 3,000-5,000 IU of vitamin D per day – indicating the current recommended intakes are not high enough to raise and/or maintain the vitamin D levels necessary for proper health.”

I still haven’t found the best brand, but I really like these drops I found at feelrite.  I just mix them into my protein shake and I’m good to go.  I’ve been seeing some improvement with my psoriasis.  Not much, but enough to keep me going.