The reason all of these headlines are misleading is because it is extremely difficult getting good evidence for which foods are good for you and which foods aren't. As I've written before, "you can’t prescribe someone a course of celery for 20 years, and compare how well they do to someone on a celery placebo." Instead, researchers have to use alternative methods - methods such as trying celery-derived chemicals in dishes, or asking people how much celery they've eaten over the last 20 years and relying on their memory not to be too faulty, or seeing the effect of eating celery on some measure like how dilated your blood vessels get. But none of these translate well into the wider question of "will eating lots of this food make me live longer?"