For example, say I'm super active and outdoors every day, my D levels are great. Then I get, say, Covid-19, and I stay inside for a week feeling icky. If I'm not recovered yet, are my D levels still good? Or am I now at higher risk for Covid complications because my D has decreased?
There are all sorts of questions that could be answered by understanding this better. If I am outdoorsy and take a day to work inside on a project, should I supplement that day? What if I am a tech worker who is inside most days but I do 2-3 outdoor activities per week? Am I good? Or should I be supplementing?
If I take a D supplement and 2 hours later take a D test, does it matter? What about when I first wake up and haven't been in the sun for 10 hours?
I have no idea the answer to any of these questions (as a tech worker who supplements, goes outside for hikes/rides 2-3/week, and has a Vitamin D test sitting on my self, wondering when I should take it...)