[blithedale]

Thank you thank you thank you. There is a craze for popping Vitamin D related to the raft of observational studies, here... so many of which never find a causal link.

Take my own particular condition: an inherited vascular dysplasia which causes frequent nose and GI bleeds. People with low Vitamin D seem to have a worse time of it in OBSERVATIONAL studies.

But people with GI bleeds so bad they have daily diarrhea from hemorrhages and anemia that disables them to the point they can't work aren't going to be out in the sun, and aren't going to be able to absorb as many vitamins in their gut due to the havoc the hemorrhaging is yielding.

Thinking really hard about the direction the arrow of causality runs here is massively important. Is it:

LOW VITAMIN D ---> BAD BLEEDING?

Or:

BAD BLEEDING ---> LOW VITAMIN D

And as the consequences of overdosing show, this isn't like popping an extra Metamucil cracker a day or something - dire stuff can happen.

[ellyagg]

People dose themsevles with OTC vitamin D all the time, including me. It doesn't appear to be a crisis. C19, otoh...

You saw the apparent effect size in this study, right?