Not read the Vitamin C literature but there is an obvious contradiction in what you say.

ie how can you have sometime which is both obviously beneficial - backed up by dozens of studies and yet complain about lack of research - if it's so clear then why do we need more research?

I also suspect doctors don't require FDA etc approval if they wanted to prescribe vitamen C - so what's stopping them? Lack of research? But I thought you knew?

Having said all that it is beyond all doubt true that commercial organisations can't afford to spend money on researching drugs with no prospect of return - however I wouldn't characterise that as evil big pharma blocking something - it's simply just that's it's not their role.

That role belongs to organisations either funded directly by the public ( charities ) or indirectly ( taxes ) for the greater good.