Well, I Have to Know, so off to Google I go. According to this information
from Procter & Gamble, menÂ´s perspiration is acidic with a pH of about 5.6, with 7.0 being neutral. Much research has been conducted into the rigorous preservation of leather as used in bookmaking. IÂ´d say that much of what has been learned would apply to leather shoes. These guidelines
for the conservation of leather bookbindings say that deacidification should be done when the pH is less than 3.0 and buffering can be done when the pH is less than 4.0. They warn against applying a buffer to leather with a pH higher than 4.0 because the pH may increase to between 6.0 and 7.0, thus "such leather becomes unstable and discoloration may occur." Taking the leap of making an analogy between preserving book leather and preserving shoe leather, I believe nothing needs to be done to neutralize the acidity that comes from an average man`s perspiration. I recall that diluted baking soda has a pH in the low 8-range so I think, given the above, its use in shoes may actually be harmful. A little knowledge is dangerous. If anyone has anything to add or correct, feel free to jump in.