Your digestive system is saturated with gastric juices that are key to digesting the foods you eat, and when hydrogen combines with chloride inside your stomach it creates hydrochloric acid (HCL) -- yes, that's the same hydrochloric acid used in fertilizers, dyes and, as it turns out, in the fracking process.
If the acid in your stomach is strong enough to dissolve metal, which it is (it's also used in electroplating), why doesn't your stomach digest itself? You can thank mucus for that. Mucus coats the lining of your stomach, protecting it from being broken down along with everything in your stomach. Thanks, mucus!