Vitamin C (Calcium Ascorbate)
Also known as: calcium L-ascorbate, calcium ascorbate dihydrate, buffered vitamin C, E302
Calcium ascorbate is the calcium salt of vitamin C, commonly supplied as the dihydrate. It is a non-acidic, gentle-on-the-stomach vitamin C source that also contributes a small amount of calcium, so it is popular in buffered vitamin C tablets and in formulas where a sodium-free buffered form is wanted. Per gram it supplies roughly 820 mg of ascorbate and about 95 mg of calcium.
Research summary
Dissociates to ascorbate and calcium ions in the gut; the ascorbate is absorbed and functions identically to ascorbic acid.
Dosage
Daily amounts, elemental (82% of the compound is the element).
| 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 of vitamin C for adults 19+; applied to ascorbate content
Doses are mg of ascorbic acid equivalent. Elemental fraction 0.82 is stoichiometric for the dihydrate: two ascorbate ions (2 x 175.1) divided by calcium ascorbate dihydrate MW 426.3 = 0.82; anhydrous material is closer to 0.90, so verify against the supplier CoA. 1,000 mg vitamin C needs about 1,220 mg of the dihydrate and brings roughly 115 mg calcium (9.4 percent of the salt). Same RDA and UL as ascorbic acid.
Standardization: ≥98% calcium L-ascorbate dihydrate
Source material: synthetic (ascorbic acid neutralized with calcium carbonate)
Forms of Vitamin C
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Vitamin C (Calcium Ascorbate) | 250–1,000 mg | 82% | Capsule, Powder, Tablet, Gummy, Liquid | low |
| 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 (Ascorbyl Palmitate) | — | 42% | Softgel, Liquid, Capsule | mid |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Neutral taste; works well in chewables and buffered tablets.
Formulation notes
Adds calcium; include it when totaling calcium in a formula. Sodium-free alternative to sodium ascorbate.
- Has an upper limit
Sources
Related ingredients
Vitamin C (Ascorbic Acid)
VitaminAscorbic 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.
Typical: 250–1,000 mg
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
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