My understanding is that we make Vit D from sun hitting our skin, which uses cholesterol to make the D we need...so we NEED cholesterol! What about all those people (like my FIL) who take cholesterol reducers? This is impairing their already reduced (because they are elderly) ability to make vitamin D!

Another thing: if PDers have low cholesterol (as several studies I have read recently indicated) then they need Vit. D supplements even more, because even if they sit in the sun, they don't have as much cholesterol as non-PDers to make Vitamin D.