There are a ton of false beliefs especially in the nutrition field and I feel most of us lack the education to research. Can you please suggest a method to research, how to find studies, how many different sources are necessary?
Google scholar is pretty good, most universities/colleges will also have an accessible search tool through their library website, although you won’t be able to bypass the paywalls without a login.
The number of sources isn’t as important as the quality and how well the source fits in relation to others. Research usually builds on previous research, so you may have 20 studies that are built on faulty premises and one really great breakthrough study, or you may have 20 really great studies and one really off base study that nobody can replicate.
If you don’t have specific knowledge in a field (or even if you do) I’d recommend starting with a literature review, that way you can get a good sense of what research is out there without too much digging, and you get a handy list of references at the end if you want to dig deeper.
If you find a paywall blocked study that you’re really interested in but don’t want to pay the journal you can either use scihub or get in contact with the lead researcher, they’re usually willing to send you a copy.
If you want to get into reading scientific research, try pubmed. Lots of full text research articles in it, or citations to stuff that you can grab on the cannot-be-named scientific hub.
Best place to start is with a topic and a meta analysis of it. That’ll give you a summary of current knowledge. So you don’t have to plow through 50 articles yourself. Google the names of the authors and see where they come from. Then look at the journal and look up the editorial board and see where they come from. They should be from reputable universities and research institutes.