Paleobird, I absolutely share your skepticism about the supplement industry and supplementation in general. I specifically detest the "nutrient-chasing" mentality of conventional medical thought that fitmom mentions. I'll only consider supplementing things that have a reason to be deficient even in the face of an ideal diet, like magnesium (b/c our soils are so deficient that even a perfect diet can't supply enough to make up my lifelong overuse of it to feed my lifelong sugar habit). D is one of those things b/c of our sun phobia. I think about Vikings a lot, too - they, and other Northern peoples, consumed vast quantities of fat soluble vitamins (A, D, K) via oily animals of the sea, and they were outside a great deal more than we are. Anyone who is not very fair is at an even greater risk of deficiency at northern latitudes.
This is only tentative anecdotal evidence, but my husband started taking D a few weeks ago, and within two weeks, the eczema he's had for decades is nearly gone. He's off of it now to see if it comes back. The D was the only change he made. We like experimenting with ourselves, lol.
I personally intend to continue increasing my family's un"protected" outdoor skin time forever - but keep my mind open to D supplementation when we don't succeed.
5'4" 39yo mother to five sweeties & married to their AMAZING DaddyGrok
Current Weight: 175lb__________________________________Goal: 135lb
Deadlift: 240lb________________________________________Back Squat: 165lb
Bench: 130lb__________________________________________Pre ss: 85lb
***Winning a 20-year war against binge eating disorder***