What Happens When Sodium Bicarbonate and Acid Meet in the Stomach?

When sodium bicarbonate and acid meet in the stomach, a chemical reaction occurs that lowers the acidity of the stomach. For this reason, sodium bicarbonate is commonly used in antacids. When taken as an antacid, it works to neutralize stomach acid and produce relief from indigestion. This is because the reaction between these substances happens quickly, soon after the sodium bicarbonate is ingested. While useful as a short-term antacid, sodium bicarbonate's effects don't last very long, and it's not recommended for people with certain health conditions.

When too much of it is produced, the acid that normally aids in digestion can cause upset stomach. Sodium bicarbonate reacts with the hydrochloric acid present in the stomach. This reaction results in a reduction of hydrochloric acid, lowering the overall acidity of the stomach. As measured on the pH scale, the stomach's acidity can go from a very acidic two or three to a seven, which is neutral. For many people with indigestion, the result is fast, short-lasting relief from upset stomach.

Sodium bicarbonate is more commonly known as baking soda and has the chemical formula NaHCO₃. The meeting between sodium bicarbonate and acid, in this case hydrochloric acid (HCl), can be given as NaHCO₃ + HCl. The products of this irreversible reaction are NaCl, H₂O, and CO₂. These final products are commonly known as sodium chloride, water, and carbon dioxide, respectively. Other antacids work by producing reactions similar to the one that occurs between sodium bicarbonate and acid.

The carbon dioxide released when sodium bicarbonate and acid react is responsible for some side effects of sodium bicarbonate use. These include burping and gas or a feeling of being bloated in the stomach or abdomen. These effects may be more noticeable after an especially large meal.

Sodium bicarbonate is not recommended for people with high blood pressure, heart disease, or impaired kidney function. This is due to the large amount of sodium it contains. People on a low-sodium diet could negatively affect their diet by taking a couple doses of some sodium bicarbonate antacids.

In people with kidney disease, taking sodium bicarbonate can possibly cause systemic alkalosis. This is a change in the normal pH of the body, which is maintained in a specific range. People with the above conditions may want to ask their doctor about which antacid to choose. This also applies to people who suffer from frequent indigestion.