As we have reported here at Maggie's for many years, they probably are mostly bunk.
That's why wise people are always skeptics about "studies." Ten years ago, transfats were to save us from butter. Now, vice versa. Ten years ago, broccoli was good. Now, it's said to be carcinogenic. Ten years ago, the experts told us to avoid fats. Now they tell us they made a mistake; bacon is back and carbs are the bad thing (I think this seems correct from what little I know about insulin and carb metabolism). I take to heart little of what I read, but I read it anyway. Reading is recreational, often entertaining, and beats hard work.
Were I to live with no TV, no internet, and no newspaper, I think I would be a wiser man to simply focus on my daily experiences.