Acidity or alkalinity is generally acknowledged to be a measure of fluids.
Researchers have known that proper acidity or alkalinity of soil and water
are essential for plant growth and that life depends on keeping the acidity
of blood and other bodily fluids within a narrow range. The pH of normal
blood is 7.4, which is mildly alkaline, if the pH drops 1 point -- becoming
acidic -- the result would be death. People with disease tend to have an
imbalance in the pH of their blood which occurs more frequently on the acidic
side and is known as acidosis. As I understand it, most doctors consider
acidosis or alkalosis as "symptoms" of disease, but there is a school of
thought that acidosis may actually serve as a host environment for bacteria
and viruses causing them to thrive.

The point of all this as it relates to "paleo" is that almost all the fluids
we drink are acidic as a result of some processing, chlorination, etc., and
while we address foods as they are found in nature we may be overlooking
fluids.