The reason a lot of things arent used by doctors isnt because it doesnt work, but because N.I.C.E can't afford the studies to put into them as their money is going elsewhere.
An example of these is intestinal permeabilitiy. In conventional medicine, it doesnt exist, but in general Science its well accepted. You just need to drink a polypeptide substance and then measure it excrete din your urine to prove that your gut is permeable for large molecules, yet doctors dont understand this.
The actualy biology that doctors study is quite basic. My girlfriend is in her 4th year of medicine and I have seen the entire syllabus. I have myself studied anatomy and physiology in a lot more depth than most doctors will ever. The cutting edge is where the PHD's are, not medical doctors.