The Different Forms of Vitamin C

Ascorbic Acid vs Ascorbate

The Different Forms of Vitamin C

Ascorbic Acid vs Ascorbate

Ascorbic acid and ascorbate salts (e.g., sodium ascorbate and calcium ascorbate) are all considered vitamin C. Ascorbic acid converts to ascorbate and vice versa according to the pH of the fluid that they are in, such that both are present in the body. Furthermore, these forms convert to two oxidized forms in the body, semidehydroascorbic acid and dehydroascorbic acid, which in turn convert back to ascorbic acid/ascorbate.

Vitamin C supplements contain ascorbic acid or ascorbate or a mixture of the two. There is no difference in bioavailability. Ascorbic acid, which is a weak acid, can be more irritating to take than ascorbate, which is very slightly alkaline (having a near-neutral pH).

Most vitamin C supplements are mostly or all ascorbate, and vitamin C mostly exists as ascorbate in the body.

Labeling regulations often require the amount of vitamin C in a supplement to be given as milligrams of ascorbic acid, even if the vitamin C is present as ascorbate. Such labeling helps the consumer understand how many molecules of vitamin C they are getting.

As an example, a label may state a dose of “1120 mg sodium ascorbate (equivalent to 1000 mg ascorbic acid)”. The difference in masses (1120 mg versus 1000 mg) is due to a molecule of sodium ascorbate being heavier than a molecule of ascorbic acid.