Calcium Ascorbate vs. Sodium Ascorbate
Among 1,369 on-market vitamin c products with an identifiable primary form, 84.2% use Calcium Ascorbate (1,153 products) and 15.8% use Sodium Ascorbate (216).
| Calcium Ascorbate | Sodium Ascorbate | |
|---|---|---|
| Quality tier | Tier 2 | Tier 2 |
| Vitamin C by weight | — | — |
| Share of market | 84.2% | 15.8% |
| On-market products | 1,153 | 216 |
| Median declared dose | 167 mg middle half: 90–400 | 120 mg middle half: 30–500 |
| Most common brands | Carlson, Ultima, American Health | XYMOGEN, Nature Made, Greens Today |
Doses are declared per serving in mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why Calcium Ascorbate is tier 2
Not shown more bioavailable than plain ascorbic acid in the cited comparison (result not independently confirmed); it delivers less vitamin C per mg of ingredient mass (about 83-90% ascorbic acid by mass for the dihydrate/anhydrous salt) due to the bound mineral. A reduced GI/acid-irritation advantage is commonly claimed but is unsourced here.
Source: Johnston CS, Luo B. 1994, PMID 8021423
Why Sodium Ascorbate is tier 2
Same rationale as calcium ascorbate -- a buffered mineral salt not shown more bioavailable than ascorbic acid.
Source: Johnston CS, Luo B. 1994, PMID 8021423