I had chronic diarrhea for two years. I had LOW stomach acid. When I started taking Betaine Hydrochloride it stopped the diarrhea in two days. I take 3 or 4 500mg capsules per meal. Relief is very dose related. It depends on how much you eat and what you eat. Every person will have to experiment to find the best dose.
If a person has uclers or irritated bowels consult a doctor because the supplemental acid might hurt.