What is the Difference Between Lactate and Lactic Acid?

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Lactic acid and lactate are chemically similar, but they differ by a single hydrogen atom. An acid is a substance that can donate hydrogen ions (H+), and lactic acid is such a substance. When lactic acid donates a hydrogen ion, the resultant product is referred to as the conjugate base of lactic acid, which is lactate.

The main difference between lactic acid and lactate lies in their chemical properties:

  • Lactic Acid: Contains an extra hydrogen ion, which makes it an acid. It can donate this hydrogen ion to make the environment more acidic.
  • Lactate: Lacks the extra hydrogen ion, making it a base (or more accurately, a conjugate base). Lactate is produced by the body in response to aerobic exercise and serves as a fuel for the cells.

Under physiological conditions (the environment within the human body), most of the lactate will be dissociated, and strictly speaking, it will be in the form of lactate. During exercise, the body produces lactate, not lactic acid. Although the terms "lactate" and "lactic acid" are often used interchangeably, they have different chemical properties. In summary, lactic acid is an acid that contains an extra hydrogen ion, while lactate is the conjugate base of lactic acid, which is produced by the body during exercise.

Comparative Table: Lactate vs Lactic Acid

The main difference between lactate and lactic acid lies in their chemical structure and the conditions under which they exist. Here is a comparison table highlighting the key differences:

Feature Lactate Lactic Acid
Definition Lactate is a carboxylate, which is the anion that results from the dissociation of lactic acid. Lactic acid is a carboxylic acid, which can donate a hydrogen ion (H+).
Production Lactate is produced through the dissociation of lactic acid. Lactic acid is produced as a byproduct of anaerobic respiration in muscle cells.
pH Conditions At physiological pH (within the human body), most of the lactate will be dissociated and exist in the form of lactate. Lactic acid is formed when lactate accepts a hydrogen ion, usually under acidic conditions.
Role in the Body Lactate is a byproduct of anaerobic respiration and can be used to generate more ATP in the Cori Cycle. Lactic acid is initially produced in muscle cells during anaerobic respiration and then dissociates into lactate ions, which can be converted back to glucose in the liver.

It is common for lactate and lactic acid to be used interchangeably in general discussions, but they are technically different compounds.