The GPs ("family" doctors) I've met do not seem too worried about shrinkage of their practice. Mostly they're overworked and faced with diseases brought on by bad diet, smoking, and other preventable causes that they do not have very good tools to treat. However, they are very cautious and suspicious of fads. They live in a world where the "standard of care" (i.e., what one must do not to be liable for malpractice) is established by mainstream nutritionists. If a patient says "Should I try this new diet?" the doctor is under enormous pressure to point out that it is inconsistent with the conventional wisdom.

So perhaps the behavior you have described is just part of the usual process of picking up cues from patient questions.

On the other hand, specialists and pharmaceutical companies would have to make major changes to cope with a radically more healthy population. Resistance is natural.

The only long term solution, if you want established medicine to embrace new protocols, is to change the standard of care. Good luck!