Does sodium bicarbonate (NaHCO3) convert to acid in the bloodstream?

From the Guidelines

No, bicarbonate does not turn into acid in the bloodstream, but rather plays a crucial role in maintaining the body's acid-base balance by neutralizing excess acid and forming carbonic acid, which is then exhaled as carbon dioxide. Bicarbonate is a critical component of the body's buffer system, and it functions as a base in the blood to help maintain proper pH balance 1. When excess acid enters the bloodstream, bicarbonate ions (HCO3-) neutralize the acid by combining with hydrogen ions (H+) to form carbonic acid (H2CO3), which then breaks down into water and carbon dioxide that can be exhaled through the lungs.

The bicarbonate buffer system is one of the body's primary mechanisms for preventing dangerous shifts toward acidosis. The kidneys also play an important role in this process by regulating bicarbonate levels - they can conserve bicarbonate when blood becomes too acidic or excrete it when blood becomes too alkaline 1. This sophisticated system helps maintain blood pH within the narrow range of 7.35-7.45 that is necessary for proper cellular function and overall health.

Some key points to consider include:

• Carbon dioxide is a product of the body's metabolism and is cleared from the body by being transferred from the bloodstream into the alveoli in the lungs and then exhaled from the lungs 1.
• Carbon dioxide is carried in three forms in the blood: bicarbonate (70–85%), dissolved carbon dioxide (5–10%), and bound to haemoglobin (10–20%) 1.
• Increased levels of carbon dioxide will stimulate ventilation, thus increasing clearance from the lungs and therefore from the bloodstream 1.

Overall, the body's acid-base balance is a complex process that involves the regulation of bicarbonate and carbon dioxide levels, and bicarbonate plays a critical role in maintaining this balance by neutralizing excess acid and preventing shifts toward acidosis 1.

From the FDA Drug Label

Sodium bicarbonate in water dissociates to provide sodium (Na+) and bicarbonate (HCO3-) ions Bicarbonate anion is considered "labile" since at a proper concentration of hydrogen ion (H+) it may be converted to carbonic acid (H2CO3) and thence to its volatile form, carbon dioxide (CO2) excreted by the lung Normally a ratio of 1:20 (carbonic acid: bicarbonate) is present in the extracellular fluid.

Bicarbonate Conversion: Bicarbonate can be converted into carbonic acid in the bloodstream, which then converts to carbon dioxide. This process occurs when there is a proper concentration of hydrogen ions.

• The conversion is part of the body's mechanism to regulate acid-base balance.
• The resulting carbon dioxide is excreted by the lungs. 2

From the Research

Bicarbonate and Acidosis in the Bloodstream

• Bicarbonate plays a crucial role in maintaining the body's acid-base balance, with the carbonic acid/bicarbonate (H2CO3/HCO3-) couple being the most predominant extracellular buffer to keep plasma pH within a physiological range 3.
• Metabolic acidosis is defined as a pathologic process that increases the concentration of hydrogen ions (H+) in the body and reduces the bicarbonate (HCO3-) concentration, which can be caused by various factors including increased endogenous acid production, accelerated loss of bicarbonate, and primary defects in renal acidification 4, 5.
• The administration of sodium bicarbonate has been used to treat metabolic acidosis, but its efficacy and potential harm have been debated, with some studies suggesting that it may cause paradoxical respiratory acidosis, intracellular acidosis, and other adverse effects 6.
• However, other studies have found that treatment of metabolic acidosis with sodium bicarbonate can improve kidney and patient survival in patients with chronic kidney disease (CKD) 7.
• The calculation of the serum anion gap can aid in the diagnosis of metabolic acidosis, classifying the disorders into categories of normal (hyperchloremic) anion gap or elevated anion gap 4, 5.

Bicarbonate Conversion to Acid

• There is no direct evidence to suggest that bicarbonate turns into acid in the bloodstream, but rather that it plays a role in buffering excess hydrogen ions and maintaining acid-base balance 3, 5.
• Metabolic acidosis can occur when the body's buffering capacity is overwhelmed, leading to an accumulation of excess hydrogen ions and a decrease in bicarbonate concentration 4, 5.
• The use of sodium bicarbonate to treat metabolic acidosis is aimed at replenishing the body's buffering capacity and restoring acid-base balance, rather than converting bicarbonate to acid 6, 7.