It’s one of the age-old medical flip-flops: First coffee’s good for you, then it’s not, then it is — you get the picture. Today, in 2015, the verdict is thumbs up, with study after study extolling the merits of three to five cups of black coffee a day in reducing risk for everything from melanoma to heart disease, multiple sclerosis, type 2 diabetes, Parkinson’s disease, liver disease, prostate cancer, Alzheimer’s, computer-related back pain and more.