“those who drank two to three [cups of coffee] a day were the least likely to develop mental health problems”

Most useless kind of study. Participants were asked how much coffee they drank at the start of the study and never asked again. Thirteen years later their records got reviewed for mental health diagnoses. So there is no confirmation of what their coffee consumption actually was at the start, and no idea of how that consumption changed over the course of 13 years. Just bullshit.

I can't read the study, do they define a cup? Or is it the ever nebulous 'a cup of coffee'. My machine claims a cup is 5 oz, some say 6, some of us don't even agree how big an ounce is. I thought scientists were supposed to use ml!