We've seen this many times before. One day doctors say X, Y and Z are good for you, only to change their minds a few months or years or decades later. How do we ever know what to believe? There's really no answer to this, of course. Physicians and other medical professionals work hard to learn all about the human body and how it responds to everything from food and exercise to drugs, tests and medical interventions. Sometimes their advice is good, sometimes it's bad, sometimes it's neutral.
Although the 21st century is still in its infancy, doctors have already changed their opinions on many things. Here are 10 of the more prominent medical issues where they've rethought conventional wisdom -- or at least they're vigorously debating it. Because even doctors can't always agree with one another.