Over alkalinity is dangerous but hard to accomplish, usually only from pharmacuetical drugs and certain kidneys diseases can raise ph high enough to cause concern ! However over acidity can accur fairly easily and this in turn destroys electrolyte balance causing system failures!
7.4 is considered balanced blood ph but gut ph is lower or should be lower in almost all cases below 7.4 making it the perfect ph for killing bacteria. No amount of alkaline foods will drive it too high!
I beleive the real dangers in ph imbalance accur when dead highly acidic junk foods are consumed! Those on a whole foods diet including meats and such are readliy digestible and cause no disturbances in the body! Contrary to the PC veganists!