I am not sure that the evidence is conclusive enough for me to believe the validity of the claims.

I don't either. The anecdotal evidence is the usual crap that you'll see for anything, and the research they cite is equivocal or only distantly related or worse (someone linked a blog post arguing for this on LW in the past and I pointed out that most of the points were awful and one study actually showed the opposite of what they thought it showed, although I can't seem to refind this comment right now).