Sodadigest Baking soda is an effective, fast-acting antacid, an agent that neutralizes excess stomach acid. As a weakly alkaline substance, it reduces the acidity of the stomach, normalizing its pH and thereby reducing the symptoms of heartburn. The active substance in Sodadigest tablets, Sodium hydrogencarbonate, is of pharmaceutical quality, purified and thoroughly tested, and therefore more effective and safer to use than food.