Calcium Carbonate vs. Dicalcium Phosphate
Among 5,062 on-market calcium products with an identifiable primary form, 47.2% use Calcium Carbonate (2,391 products) and 24.2% use Dicalcium Phosphate (1,226).
| Calcium Carbonate | Dicalcium Phosphate | |
|---|---|---|
| Quality tier | Tier 2 | Unrated |
| Calcium by weight | 40.0% | 23.3% |
| Share of market | 47.2% | 24.2% |
| On-market products | 2,391 | 1,226 |
| Median declared dose | 130 elemental mg middle half: 50–300 | 98.13 elemental mg middle half: 50–166 |
| Most common brands | Wonder Laboratories, DC, 21st Century | The Vitamin Shoppe, DC, Mason Natural |
Doses are declared per serving in elemental mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why Calcium Carbonate is tier 2
Absorption consistently ~20-27% lower than citrate in a meta-analysis; requires stomach acid/food co-administration for optimal absorption.
Source: Sakhaee K et al. 1999, Am J Ther 6(6):313-321, PMID 11329115
Why Dicalcium Phosphate is unrated
No specific human comparative bioavailability study vs carbonate/citrate was verified.
Source: uncertain -- needs review
Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology).
This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.