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.

https://www.acc.org/latest-in-cardiology/clinical-trials/201...

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.