Here's how it works-
When a person has reflux their body is out of walk and producing too much acid. If you add a base to it, you feel better, but the body is still not functioning right and it thinks "Ooooh more base! Must produce more acid!"
Apple cider vinegar works by throwing the stomach back into balance. It makes it so acidic that it forces the body to produce more base instead. When used as the "cure" it eventually helps the body to regulate itself.
Now, that's for a healthy-ish person with a normal stomach. It worked for me and got me off of malox several times a day.