These questions may not be easy to explain or understand !
But what may be involved in this process, may have to do with the Spiritual being more powerful than the physical, and thus the Electro-magnetic Energy flow given off from a "Healer" may depend upon how well they may have learned to control their Spiritual thoughts as to if they are able to project Positive or Negative Energy flow !
Since the body is made of Flesh and Blood and this is High in Proteins and these Proteins are made from Nitrogen and since Nitrogen is an Isotope, this may mean that the body may be changed from being Acidic to Alkaline or vs by just changing the Isotope of Nitrogen !
And this may be changed by the Spiritual flows of Energy !
So, it may Depend upon the Spiritual thoughts more than the physical pH of Acidic or Alkaline !