On Wednesday, November 28, 2018 at 3:16:49 PM UTC-5, wrote:

"b) If the mechanism by which it functions is not understood, then neither is the difference between therapeutic and toxic levels."

Hold on there. That statement is off somehow. There is always a difference between therapeutic and toxic. It is true however, that some are more important than others. What's more, the levels needed or toxic will vary person to person especially among those with different lineage. There is proof of this though indirect.

I repeat: If you do not know how a mechanism functions, nor what it actually does, nor why it exists, then you cannot know whether it is operating properly or not, whether it is necessary, or not. And whether what it is producing is useful, or not. Nor are you able to recognize, understand, or describe why a given mechanism may be good (therapeutic) or bad (Toxic).

Keep in mind that the core of your premise is that these "72" are necessary for proper metabolism, that is, life. Per William of Occcam, It either is, or it ain't. Can't be both.