Hi! Apparently (according to Hveragherthi on the Truth in Medicine forum), when you take a half dropperful of bitters and place it on the back of your tongue, that causes the nerves on the back of your tongue to work in such a way that it encourages your stomach to put out its own natural acid in response to that stimulus. If you check his forum and search on bitters, there will be tons of info, and his expalanation will be more precise. He advocates grape bitters by Planetary Herbals. I use those now. I used to use Sweetish bitters by Gaia, and he thinks those are pretty good too. He just says stay away from Swedish bitters - I forget why though. He says, though, that any bitter herb can be used as "bitters". You can make your own if you are into that sort of thing. I don't ever have time for such activities, so I just use the store bought ones.