Vitamin D responsible for racial disparities in health?

I got interested in vitamin D a few years ago because I was trying to figure out a plausible explanation for why many of the genetic variants implicated in lighter skin seem to have risen in frequency relatively recently, 10,000 years ago, when modern humans have been extant at higher latitudes on the order of 30,000 years. So I started mooting the speculative idea that the switch to agriculture might have reduced vitamin D levels. Initially I assumed that rickets was the main issue, but over the past few years there has been a veritable explosion in the medical literature pointing to correlations between ill health and low vitamin D levels. The proportion of these which are randomized controlled trials are low. Unfortunately, health related topics tend to go through fads, so I've not been posting much about vitamin D. But this report is interesting, Study Links Vitamin D, Race and Cardiac Deaths: