There is so much rubbish out there regarding which vitamins are good and which are bad.
And what we’ve learned in the last five years or so is that “studies” can tell you anything. The fact that it’s a study doesn’t mean much, in other words, because you need to know how reputable the researchers are, how large the study was, how well designed and executed it was, etc.
So the new standard seems to be a combination of two things:
Massive collections of studies
This infographic attempts to capture this combination. It shows which supplements have not just a study or two or seven showing that they’re beneficial, but dozens or hundreds.
My advice to you is to use this type of filter when evaluating science. Take it as a body of work over time, and don’t be overly convinced by single or even multiple studies done in short spans.
If the study found something interesting it will very likely lead to much more scrutiny that will show it to be true. And if you don’t hear much more about it then it probably didn’t have significant merit.
There are exceptions to this for all sorts of reasons, but I think this is the best way to proceed. The alternative is to change your behavior every time a new study comes out, which is simply impractical and reckless.