D supplements as well as fish oil were thought promising until studies showed they did not really do what they were advertised to do in supplement form.
How typical that you get downvoted when you're one of the few here to actually cite a source for your claim.
I do wonder though if this is an important caveat though:
> among healthy participants.
.. since the rest of the discussion resolves around adding supplements to fight shortages. If "healthy" implies not have said vitamin D shortage then that is still a useful study but doesn't disprove the thesis that taking supplements is probably a good idea.
https://www.acc.org/latest-in-cardiology/clinical-trials/201...