Has anyone ever done a study on the persistence of bad science in the population? How long after a bad study is debunked do people still believe in it? What are the factors that affect the half-life of a misunderstanding? How many people are still trying to avoid all salt in their diet in order to live longer, but are actually killing themselves? How many people are gobbling down antioxidants for no particular purpose?
I sometimes try to run my own experiment in this area by trying to convince people that the germ theory of disease is pretty well-established and that getting rained on, or getting cold, or getting cold while getting rained on won't actually make you catch your death of pneumonia. I rarely succeed and, sometimes, people violently reject the very idea. (No, being wet and cold doesn't lower your resistance or affect your immune system.)