I had a look at the product stomacin-u and it's made of raw cabbage. Raw foods are full of digestive enzymes (heat destroys enzymes). Digestive enzymes break down foods and help prevent acid reflux.
My mother takes digestive enzymes in capsule form. For low stomach acid she takes betaine HCI with pepsin. Apple cider vinegar is another way to increase stomach acid. Production of stomach acid and digestive enzymes decrease as we age. She no longer suffers GERD, LPR (suffered both severely for 5 years) and is 95% improved with gastritis (suffered for 25 years - 5 severe on acid blocker nexium).
Also check for H Pylori bacteria, any obstructions such as hiatus hernia, nutrient deficiency states needed for stomach acid production such as zinc, sodium, vitamin B1, vitamin B6. Low magnesium also affects the esophageal sphincter and lowers production of digestive enzymes. Medical conditions such as hypothyroidism also lower stomach acid production and enzymes.