Sodium bicarbonate (NaHCO₃) primarily acts as a buffer to neutralize acids and is used as a drug in various medical applications including dental care products and antacids (to treat heartburn and indigestion, also known as dyspepsia).^[2] Sodium bicarbonate is also sometimes used to treat acidosis in critical illness^[3][4] and as a sports supplement for improving performance.^[1][5] In the body, bicarbonate is produced by the kidneys and circulates in the blood to buffer changes in pH.^[6][7]

Note that sodium bicarbonate is commonly known as baking soda in the US and Canada (or bicarbonate of soda in the UK, NZ, and Australia). This is not the same as baking powder, which contains sodium bicarbonate mixed with an acidic ingredient.

Supplementation with sodium bicarbonate before exercise has been found to enhance exercise performance, particularly during high-intensity activities lasting between 30 seconds and 12 minutes, during tests assessing muscular endurance (e.g., tests measuring reps to failure or time to maintain a constant isometric force), and in combat sports.^{[1][8][9][10][11][12][13]}

Sodium bicarbonate is sometimes used intravenously in emergency settings to treat metabolic acidosis, but its use in this context is nuanced.^[3] For example, the use of sodium bicarbonate in newborns or people with diabetic ketoacidosis is controversial due to potential adverse effects.^[14][15][16]

In people with advanced chronic kidney disease (CKD), some evidence shows that treatment with sodium bicarbonate is associated with a lower risk of cardiovascular events, hospitalization, and mortality.^[17][18] Some small studies have also shown that an intravenous infusion of sodium bicarbonate can prevent kidney problems caused by the dye used during angiography, a procedure used to identify the narrowing of blood vessels in the heart. However, large, well-designed randomized controlled trials^[19][20] and meta-analyses^{[21][22][23][24]} do not confirm this benefit. That said, sodium bicarbonate might prevent contrast-induced acute kidney injury in people with preexisting kidney disease.^[25]

Some antacids, which are drugs used to treat heartburn, indigestion, and gastroesophageal reflux disease (GERD),^[26][27] contain sodium bicarbonate. However, the specific effect of sodium bicarbonate on these conditions is unclear because many antacids also contain other ingredients, including aluminum hydroxide, calcium carbonate, and magnesium hydroxide, and even other drugs like omeprazole (a proton pump inhibitor). Furthermore, additional evidence is needed to determine whether sodium bicarbonate directly reduces acidity in the stomach.^[28]

Sodium bicarbonate is sometimes used in dental care products to help improve dental health by reducing gingivitis and plaque.^{[29][30][31][32][33][34][35]} However, because many such products contain additional ingredients, the direct benefit of sodium bicarbonate is unclear. Furthermore, many studies showing a benefit have been conducted by dental product manufacturers.^{[30][32][33][35]} Meanwhile, some^[36][37] but not all^[38] randomized controlled trials have shown a direct benefit of chewing sodium-bicarbonate-containing gum on dental health. Further high-quality research is needed to clarify these effects.

When taken orally, doses of sodium bicarbonate higher than 0.3 grams per kilogram of body weight can increase the risk of gastrointestinal side effects, including bloating, nausea, and vomiting.^[5][1]

Although some case studies of individual patients have found adverse effects of sodium bicarbonate, these are rare,^[39][40][41] and, in general, sodium bicarbonate is considered safe for consumption when taken orally.^[1][42]

Sodium bicarbonate likely improves high-intensity exercise performance by buffering the production of hydrogen ions, preventing a drop in pH in the blood or the muscles.^{[5][1][43][44][45][46][9]}

The gastrointestinal side effects caused by high doses of sodium bicarbonate (bloating, nausea, vomiting, etc.) are probably caused by a reaction between bicarbonate and stomach acid, which releases CO₂ in the stomach.^[5][1]