That is an excellent question. You caught what I had noticed, too.
My family takes multiple supplements and eats foods that cause NO to be created, under the assumption it’s “all good.”
I have not been able to find references to clear that up.
It makes me wonder about all of those “idiopathic” emphysema cases...
A follow on discussion from two other journal articles just started here:
https://freerepublic.com/focus/chat/3803247/posts?page=1