Vitamin C (Ascorbic Acid)
Also known as: L-ascorbic acid, ascorbic acid, vitamin C, ascorbate
Ascorbic acid is the reference form of vitamin C and the most common form in supplements; NIH ODS notes its bioavailability equals that of vitamin C naturally present in food. Humans cannot make it, so it is an essential dietary nutrient used to support collagen formation, immune cell function, iron absorption from plant foods, and antioxidant defense. It is an inexpensive, stable white crystalline powder with a sharp sour taste, suited to almost every delivery format.
Research summary
Electron donor for hydroxylase enzymes (collagen prolyl and lysyl hydroxylases, carnitine and catecholamine synthesis) and a water-phase antioxidant that regenerates vitamin E.
Dosage
Daily amounts, of compound.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 90 mg | 250–1,000 mg | 2,000 mg | 2,000 mg |
NIH ODS — UL is 2,000 mg/day for adults 19+ from food plus supplements
RDA is 90 mg for men and 75 mg for women, with an extra 35 mg/day for smokers. Pharmacokinetic work in healthy volunteers tested 30 to 2,500 mg/day and showed plasma levels approach saturation at a few hundred mg/day, with absorption falling and urinary excretion rising at higher single doses, so splitting larger amounts across the day is more efficient than one large dose. Common cold trials mostly used 200 mg/day or more. Above the 2,000 mg UL the main issues are loose stools and GI upset.
Standardization: ≥99% L-ascorbic acid (USP)
Source material: synthetic (fermentation of glucose, Reichstein or two-step fermentation process)
Forms of Vitamin C
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Vitamin C (Ascorbic Acid) | 250–1,000 mg | — | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Vitamin C (Sodium Ascorbate) | 250–1,000 mg | 89% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Vitamin C (Calcium Ascorbate) | 250–1,000 mg | 82% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| Vitamin C (Ascorbyl Palmitate) | — | 42% | Softgel, Liquid, Capsule | mid |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Very sour and acidic; gummies and liquids often switch to a buffered ascorbate salt. Coated (97% ascorbic acid) grades improve tablet flow.
Formulation notes
Enhances non-heme iron absorption, so it is commonly paired with iron. Acidic; can degrade vitamin B12 and folate in liquid formulas over time. Often combined with zinc, elderberry, and bioflavonoids in immune blends.
- Has an upper limit
Sources
Related ingredients
Zinc Citrate
MineralA zinc salt of citric acid with a relatively high zinc content of about 31%, giving it a compactness advantage over gluconate and picolinate.
Typical: 10–25 mg
Vitamin C (Sodium Ascorbate)
VitaminSodium ascorbate is the sodium salt of ascorbic acid.
Typical: 250–1,000 mg
Vitamin C (Calcium Ascorbate)
VitaminCalcium ascorbate is the calcium salt of vitamin C, commonly supplied as the dihydrate.
Typical: 250–1,000 mg
Zinc Gluconate
MineralThe most common zinc salt in multivitamins, lozenges, and immune products, containing about 14.3% elemental zinc.
Typical: 10–25 mg
Vitamin E (d-Alpha-Tocopheryl Succinate)
VitaminThe succinate ester of natural (RRR or d-) alpha-tocopherol, the one vitamin E form the body maintains in plasma and the form on which the RDA is based.
Typical: 67–268 mg