Lack of proof is not the same as proof of lack. And when it comes to most items which cannot be patented and controlled by the big pharma empire and mainstream medicine - and thus represent potential threats to their obscened profits, you are not likely to see many double blind placebo controlled studies vouching for them. What few studies you will find which have positive results are most often criticized and rejected by the mainstreamers.
When it comes to educational curriculum, perhaps nowhere is it as distorted as it is in medical schools, whose primary source of funding comes from the pharmacuetical companies and whose curriculum is set by the doctors union known as the AMA. Almost nothing is taught about the role of proper diet and nutrition, very little is taught about the importance of lifestyle and stress management, and what is taught about the healing herbs and other items found in abundance in nature is mostly teaching that they are ineffective at best and danerous at worst.
What doctors are mostly taught in medical school is that the way to treat illness is to get out a prescription pad and prescribe patented approved and unnatural medicines made by guess who.
Next time you run into people who would tell you how wonderful mainstream medicine is, refer them to my article:
"Modern Medicine: How Healing Illness became Managing Illness"