I believe that the body makes itself acidic, in response to the poisoning of its enzymes, primarily by fluoride and mercury. The body chooses to lower its pH to keep reaction rates at sufficient levels to enable the person to survive with inhibited enzymes.
When the fluoride and mercury are removed, and the enzymes are no longer poisoned, then the body will adjust its pH back to normal. If that isn't right, I'll eat my Stetson.
There is no reproducible scientific basis for those who claim that certain foods are more alkalizing than others, in all people. All these books that tell you lemon juice has an alkalizing effect never mention how this was determined. I think it is the work of a whirling dervish. Merely becasue people cite web sites that make claims does not make waht is written there true. I have clearly convincing evidence of my position, and the one other main true cause of acidity, but I have five miles to run.