What is Betaine Hydrochloric Acid? GERD Acid reflux can be caused by a lack of Hydrochloric acid (also called HCL, HCL acid or betaine hydrochloride in supplement form) is considered one of the most important fluids (or “juices”) found in the human body. Betaine HCl or Hydrochloric acid or Betaine Hydrochloride is a supplement that …