[Guest0918231]

I had mine checked because I was curious when I went for bloodwork a couple of years ago. I was expecting it would be low since I work indoors on a computer all day and my exposure to the sun in winter is limited.

I think I was tested in late fall, and it was fairly expensive to have done (roughly $100 where I was in Europe). From what I remember, you're deficient if you're less than 12 ng/mL and mine was around 6 ng/mL.

Of course I want to say I feel better, experience less winter blues, get sick less often, and have more energy since I started taking a supplement. I can't be certain of any of those things though. Maybe it makes a difference, maybe it doesn't. I feel decent these days, the numbers say I should take it, so that's why I take it.