I know a person who is a strong believer in convenitional medicine. When my wife showed her liver stones to her, she wouldn't believe it. She would say things like, "Maybe the body needs it?", and was disoriented if you wish. Usually people like her stick with "If it was true, doctors would tell me about it" slogan.
Brainwashing works for a lot of people unfortunately. Many people believe what they are told rather than something they can see and touch for themselves.