There are conditions that are considered incurable by "proper" medicine (e.g. Alzheimer's disease) and discouraging people from looking elsewhere (e.g. http://www.aging-us.com/article/100690) in those cases is just as dangerous. People are capable of considering multiple options simultaneously, and should be encouraged to inform themselves about the available treatments. In cases when two medical theories are truly incompatible, give people the right to decide what gamble they want to take, and understand that, in both cases, outcomes are uncertain.