Anecdata-point: In the summer I regularly run for hours at a time (marathon training), without a shirt and without sunscreen. (I've got a good tan which seems to keep me from getting sunburned.) And yet I regularly test as low Vitamin D. A daily Vitamin D supplement suffices to keep the numbers in range.
I assume that this is a personal thing, something about my specific metabolism or skin or whatever that doesn't produce vitamin D particularly well. I have no idea if the supplement actually improves my health outcome -- I was generally healthy both before and after adding supplements.
My advice, such as it is: don't take any supplement without a doctor telling you it's needed. But if a doctor says it's necessary, yeah, do that.
I assume that this is a personal thing, something about my specific metabolism or skin or whatever that doesn't produce vitamin D particularly well. I have no idea if the supplement actually improves my health outcome -- I was generally healthy both before and after adding supplements.
My advice, such as it is: don't take any supplement without a doctor telling you it's needed. But if a doctor says it's necessary, yeah, do that.