Hypothesis by VitaminDWiki – Vitamin D levels are no longer limited by evolution
The health problems of getting excessive vitamin D from the sun/UVB are well known
Increased skin cancer
Excess calcium Death by Calcium, book by Thomas Levy – Dec 2013
The benefits of getting more vitamin D are also well known Proof that Vitamin D Works
Evolution found a balance between the benefits and risks in a very sunny climate: 50 ng
Is 50 ng of vitamin D too high, just right, or not enough
Optimum category starts with
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Chart of Vitamin D levels vs race - April 2013 has the following

With supplementation, we have an opportunity to increase vitamin D levels beyond evolutionary limits
– provided we balance the cofactors and avoid excess sun/UVB
Low cost cofactors for vitamin D
Increased Vitamin K2 reduces the problems of excess Calcium – Nov 2013
Decrease Calcium and Increase Magnesium when increasing vitamin D has the a notional chart

How much is "optimal"? We do not know, but there are some interesting clues
80 ng achieved by 2,000 patients of one doctor. Their visits by patients dropped 4X: from 4/year to 1/ year
105 ng – Resulted in a huge decrease in Psorasis
150 ng – resulted in CURING Multiple Sclerosis
Items in category Optimum Vitamin D items
GrassrootsHealth chart shows that a wide variety of health problems decrease with increasing Vitamin2 D levels

An increasing number of PubMed articles about "Optimum Vitamin D"

Personal note: My vitamin D level is typically above 200 ng