Testing stomach acid with saliva pH

"A pH test with pH paper is the easiest and quickest way to know if one's stomach acid is low. Test your saliva first thing in the morning and then again about half an hour after eating. The numbers should rise after eating, e.g. seven before and nine after. If they go down (seven to five or six), and especially if the first pH is around five and stays the same or goes down to 4.5, you need more stomach acid."