Sodium bicarbonate, commonly known as baking soda, is a chemical compound that neutralizes acids. That single property explains nearly everything it does, from settling an upset stomach to helping bread rise to keeping your blood at the right pH. It works by reacting with acid to produce water and carbon dioxide gas, a simple reaction with a surprisingly wide range of applications in your body, your kitchen, and clinical medicine.
How It Works in Your Body
Your blood naturally contains bicarbonate ions as part of a built-in buffering system that keeps your pH in a narrow, life-sustaining range (around 7.35 to 7.45). When acidic substances enter your bloodstream, bicarbonate ions neutralize them by converting excess acid into carbonic acid and water, both of which the body can easily handle. When something too alkaline enters the blood, the system works in reverse: carbonic acid reacts with the base to produce bicarbonate ions and water. This back-and-forth keeps your blood chemistry stable without you ever thinking about it.
Taking sodium bicarbonate as a supplement or medication boosts the bicarbonate side of this system, which is why it’s useful any time the body is dealing with too much acid.
Relieving Heartburn and Indigestion
Sodium bicarbonate is one of the oldest and simplest antacids available. When you swallow it, it reacts directly with hydrochloric acid in your stomach, producing water and carbon dioxide (which is why it can make you burp). The relief is fast, typically within minutes, but short-lived. Taken by mouth, its acid-neutralizing effect lasts only about 8 to 10 minutes before stomach acid production overwhelms it again. That makes it useful for occasional, quick relief but not practical for chronic acid reflux, where longer-acting antacids or other medications work better.
Treating Metabolic Acidosis
When your blood becomes dangerously acidic, a condition called metabolic acidosis, sodium bicarbonate is one of the primary treatments. This can happen in several situations: severe kidney disease, uncontrolled diabetes, serious infections, or poisoning. In hospital settings, it’s given intravenously to raise blood pH back above 7.20, a threshold below which organs start to struggle.
For people with chronic kidney disease (CKD), the kidneys gradually lose the ability to clear acid from the body. Clinical guidelines recommend considering sodium bicarbonate therapy when blood bicarbonate levels drop below 18 to 22 milliequivalents per liter. A 2024 meta-analysis of 14 randomized trials involving over 2,000 patients found that sodium bicarbonate supplementation significantly improved kidney filtration rates, suggesting it may help slow the deterioration of kidney function in people with CKD and metabolic acidosis.
For people with a condition called type 1 renal tubular acidosis, where the kidneys can’t properly acidify urine, daily oral bicarbonate is the main treatment. The dose is tailored to offset the acid load from a normal diet.
Boosting High-Intensity Athletic Performance
During intense exercise, your muscles produce large amounts of lactic acid, which contributes to that burning sensation and eventual fatigue. Sodium bicarbonate, taken before a workout, increases the blood’s capacity to buffer that acid, potentially letting you push harder for longer.
The strongest evidence supports its use in high-intensity activities lasting 1 to 7 minutes: events like 400- and 800-meter runs, swimming races, and rowing sprints. More recent studies have also shown benefits in team and racquet sports that involve repeated bursts of effort over longer periods, up to about an hour. The Australian Institute of Sport, which classifies supplements by evidence level, recommends 200 to 400 milligrams per kilogram of body weight, taken with a small carbohydrate-rich meal about 2 to 2.5 hours before competition. At the higher end of that range, blood buffering capacity stays elevated for 3 to 4 hours.
The main drawback is gastrointestinal distress. Nausea, bloating, and diarrhea are common enough that athletes typically experiment with timing and dose during training before using it in competition.
What It Does in Baking
In the kitchen, sodium bicarbonate is a leavening agent, meaning it makes baked goods rise. The mechanism is the same acid-base reaction: baking soda reacts with an acidic ingredient in the batter (buttermilk, vinegar, yogurt, lemon juice, brown sugar, or even cocoa) and releases carbon dioxide gas. Those tiny gas bubbles get trapped in the batter, creating a light, airy texture.
The first burst of gas happens as soon as the baking soda meets the acid at room temperature, which is why recipes using only baking soda (not baking powder) often tell you to get the batter into the oven quickly. A second phase of gas release occurs when the batter heats above 170°F. Without a sufficient acidic ingredient, baking soda won’t fully react, leaving a metallic, soapy taste in the finished product.
Oral Care and Cleaning
Baking soda appears in many toothpastes because it’s mildly abrasive, enough to scrub surface stains but gentle on enamel. The standard measure of toothpaste abrasiveness is the Relative Dentin Abrasivity (RDA) scale, where anything under 250 is considered safe. Plain baking soda scores just 7, making it one of the least abrasive options available. Most commercial toothpastes fall between 30 and 100. Its alkaline nature also helps neutralize acids produced by bacteria in the mouth, which are responsible for tooth decay.
Outside the bathroom, baking soda’s ability to neutralize acids makes it a common household cleaner and deodorizer. Many odors are caused by acidic or volatile compounds, and baking soda reacts with or absorbs them rather than simply masking the smell.
Risks of Taking Too Much
Because sodium bicarbonate shifts your blood chemistry toward the alkaline side, taking too much can cause a condition called metabolic alkalosis. Mild cases cause nausea, vomiting, tingling, numbness, and muscle cramping. Severe cases can lead to confusion, agitation, and seizures. People with kidney failure are especially vulnerable because their kidneys can’t clear the excess bicarbonate efficiently.
There’s also a sodium concern. Sodium bicarbonate is, as the name suggests, a sodium compound. Large or frequent doses add a significant amount of sodium to your intake, which can raise blood pressure and worsen fluid retention in people with heart, kidney, or liver disease. Current cardiac arrest guidelines from the American Heart Association specifically recommend against routine use of sodium bicarbonate during resuscitation, reflecting decades of evidence that it doesn’t improve outcomes and can cause harm in that setting.
For occasional heartburn or a single pre-competition dose in sports, sodium bicarbonate is generally safe for healthy adults. The problems arise with repeated, high-dose, or unsupervised use, particularly in people whose kidneys or heart are already compromised.