Baking Soda (Sodium bicarbonate) is one of the the many natural remedies for heartburn (GERD). It is used as an alternative to over-the-counter antacids for temporary relief of the pain.
A teaspoonful of baking soda is dissolved in 8 ounces of water to prepare the drink.
Side effects may vary by many factors influencing individuals and must be further studied before using this remedy. MedlinePlus article on Proper usage and side effects will be a good place to start.