I've been reading up on research that's found our stomach doesn't produce nearly as much or as strong acid as we've been told. I will tell you that if it were as strong as 3.5 or less pH, we would definitely destroy our upper esophagus, mouth and lips upon vomiting. The research seems to show that the level spikes up when very indigestible food is sent down, but is normally not very acidic - because it doesn't really break down most of what we eat. Our guts do most of that, with bacteria and milder proteases. If our stomach is producing a lot of strong acid, it's possibly an indicator that we're not feeding ourselves enough natural fuels. Remote people don't tend to have the kinds of heartburn issues that city people do, apparently.