The Anatomy of Life & Energy in Agriculture was updated a few years ago and thankfully the above quoted phrase survived. I can't remember whether it was from one of his lectures I attended or from a book where he stressed that a high-Brix plant (i.e., high quality) grown in toxic soil will assay lower in toxic matter than a low-Brix plant (i.e., low quality) grown in organically "clean" soil.
While we usually keep Reams-Ag and human RBTI separate, serious students can put 2 and 2 together. They should understand that the calcium-rich human subject with near perfect RBTI numbers can eat something with no distress that will just about do in their friend who ignores pH-established calcium needs to go through life with miserable RBTI numbers.
It is all about selective assimilation.