No Studies Because Drug Companies/Government Doesn't Fund Them.
I was diagnosed with colon cancer and began searching for possible treatment modes. Cannabinoids, from marijuana, have been reported in "in vitro" and laboratory rat studies to kill cancer cells without harming normal cells. Wow, that could be very significant, except there are virtually no clinical trials involving human patients. Why? Because of our government's absurd marijuana laws.
I also learned that a substance in Turkey Tail mushrooms (PSK) reduces cancer tumors, but again, there have been few clinical trials in the U.S. Why? Likely because the drug companies don't see a future profit in it, so they don't fund studies. It would be hard for them to patient a common mushroom. Japan, on the other hand, has done a lot of work on turkey Tails/PSK and it is commonly used in cancer treatment there. (See www.fungi.com)
Much of the western medical profession chooses its treatments based on large clinical trials, if no money is to made, no such trials take place. They write off "success" stories for such substances as anecdotal and ignore them. The same situation likely pertains to the micro-nutrients discussed in this post. There is no money to made from studying things which are non-patentable, thus no studies of their efficacy.
It is all about the drive for corporate profits. My chemo drug costs $2200 a month for 56 pills, there are high profits in that, thus they have been the subject of clinical trials. As usual, follow the money.