Vitamin C
Of 19,716 on-market vitamin c products in the January 2026 DSLD dump, the median declared dose is 100 mg, and 92.4% list Ascorbic Acid as the primary form.
Form share
Of 17,528 products with an identifiable primary form, here is the share held by each form of Vitamin C on the market today.
| Form | Quality tier | n | Share |
|---|---|---|---|
| Ascorbic Acid | Tier 1 | 16,190 | 92.4% |
| Calcium Ascorbate | Tier 2 | 1,126 | 6.4% |
| Sodium Ascorbate | Tier 2 | 212 | 1.2% |
Form share over time
Entry-year breakdown of the top forms, 2012–2025.
Dose distribution
Deciles of declared dose per serving (mg), among 16,563 products with a disclosed amount, against the RDA of 90 and UL of 2000.
- 46.0% of products fall below the fairy-dust threshold (100 mg, 20% of the studied low dose).
- 0.5% of products don't disclose an amount because Vitamin C is declared inside a proprietary blend.
By dosage form
By target group
Top brands
| Brand | Products |
|---|---|
| Douglas Laboratories | 391 |
| DC | 321 |
| Wonder Laboratories | 286 |
| Source Naturals | 241 |
| Nature's Way | 230 |
| Nature Made | 196 |
| Centrum | 186 |
| Cellucor | 159 |
| NOW | 155 |
| The Vitamin Shoppe | 153 |
| ProCaps Laboratories | 151 |
| MegaFood | 140 |
| Bluebonnet | 139 |
| Puritan's Pride | 134 |
| Higher Nature | 134 |
| Emergen-C | 133 |
| Pure Encapsulations | 132 |
| Life Extension | 128 |
| Metagenics | 120 |
| Country Life | 119 |
| Solgar | 118 |
| Carlson | 117 |
| Vitamin World | 115 |
| Syntrax | 110 |
| XYMOGEN | 107 |
Forms explained
Reference form; a head-to-head absorption/excretion study found no meaningful bioavailability advantage for other commercial vitamin C forms over plain ascorbic acid. L-ascorbic acid is the biologically active stereoisomer "ascorbic acid" refers to on labels.
Source: Johnston CS, Luo B. 1994, J Am Diet Assoc 94(7):779-81, PMID 8021423
Not shown more bioavailable than plain ascorbic acid; its advantage is reduced GI/acid irritation, and it delivers less elemental vitamin C per mg of ingredient mass due to the bound mineral.
Source: Johnston CS, Luo B. 1994, PMID 8021423
Same rationale as calcium ascorbate -- a buffered mineral salt not shown more bioavailable than ascorbic acid.
Source: Johnston CS, Luo B. 1994, PMID 8021423
Reference values
- RDA (adult): 90 mg — 90mg (men 19+); 75mg (women 19+); +35mg/day for smokers
- Tolerable Upper Intake Level (adult): 2000 mg — Based on risk of osmotic diarrhea/GI disturbance at higher intakes
- Studied clinical dose range: 500–1000 mg
- Sesso HD et al. 2008 (Physicians' Health Study II), JAMA 300(18):2123-33, PMID 18997197 -- 500mg/day ascorbic acid x median 8yr in >14,000 male physicians; did not reduce major cardiovascular events vs placebo. Chronic-use RCTs rarely exceed 1000mg/day; acute bioavailability studies have tested single doses up to 2000mg.
- Note: No IU convention has ever existed for vitamin C.