The issue is that people nowadays may live in a place with a lot more UV than their ancestors adapted to -- consider an Irish family that moved to Arizona, for example. The same principle of "more available than evolution prepared you for" seems also to apply.

And vice versa - consider migration from Central America to Chicago or North Africa to Stockholm.

I don't think "refined" matters, except so far as once you refine sugar, you can add it to all kinds of foods, driving consumption up. That's exactly my point--eating some fruits or honey is good for your health when every calorie is valuable. Eating tons of sugar when it's cheap and added to everything is bad for your health. Just because eating some sugar was helpful in the past doesn't imply that our bodies have evolved to process arbitrarily large amounts of sugar with no ill effects whatsoever.