I've tried Vit. D, and didn't notice much difference, although my blood levels did go up from borderline to the low end of sufficient. I'm now taking those pills on an irregular basis, and will be curious to see what my blood levels are the next time I get tested.

There's a limit to how many pills I'm willing to take per day, and I find it hard to stay enthused about any of them. So at the moment I'm not taking anything daily except the doxycycline that my eye doctor prescribed.