The short answer · Bone mineral density
Take vitamin d3 (cholecalciferol) & calcium carbonate for bone mineral density. This is the one to buy.
21st Century, Calcium Plus D3, 90 Tablets
4.7· 11,015 ratings· $0.07/serving
Vitamin D3 (Cholecalciferol) 20 mcg — below the studied 800-4000 IU window
Of 9,504 products scored for Bone mineral density, 21st Century, Calcium Plus D3, 90 Tablets ranks #1 with a DoseRank score of 92. Vitamin D3 (Cholecalciferol) and Calcium Carbonate are the strongest evidence signals for this outcome.
Retailer links may be affiliate links. Rankings and placement are never paid.
The form“Why Vitamin D3 (Cholecalciferol) & Calcium Carbonate?”Evidence Strong evidence
Vitamin D3 (Cholecalciferol) and Calcium Carbonate are the strongest evidence signals for this outcome.
- Vitamin D3 (Cholecalciferol)The pick
Strong evidence · 20 mcg
The form made by skin on sun exposure and used in most supplements; converts to active calcitriol and raises serum 25(OH)D more effectively than D2.
- Calcium CarbonateThe pick
Strong evidence · 1000 mg
The cheapest, most concentrated calcium form at 40% elemental; needs stomach acid, so take with food and expect weak uptake on acid-reducing medications.
- Calcium Hydroxyapatite
Moderate evidence · 907 mg
Calcium drawn from bone mineral, supplying calcium and phosphorus in a natural ratio with trace collagen; marketed for bone-density support.
The dose“Is the dose actually effective?”Dose fit 66
1 of 2 dosed ingredients land in the studied range. Vitamin D3 (Cholecalciferol) at 20 mcg sits below the studied 800-4000 IU window.
Vitamin D3 (Cholecalciferol)
Studied window 800-4000 IU · this pick 20 mcg
Calcium Carbonate
Studied window 500-1200 mg · this pick 1000 mg
The ranking“Why should I trust this pick?”Trust 92
Strong trust signals — consistently high marks from verified buyer ratings. Each product gets a DoseRank score blending clinical strength, evidence, dose fit, trust and value. Retailer links may be affiliate links — the scoring model decides placement, never payment from a brand.
- 9,504 products scored
- Never paid placement
- Evidence level: Strong · 88
- 647 brands
- 29 ingredients
The price“Can I do better than $0.07 a serving?”Value 88
$0.07 per serving — low price tier for this outcome. The cheapest ranked pick here is $0.03 per serving.
- 821st Century, Calcium 500 + D3, 400 TabletsScore 89 · $0.03/servingiHerb
- 221st Century, 600+D3, Calcium & Vitamin D3 Supplement, 400 TabletsScore 92 · $0.03/servingiHerb
Why not the absolute cheapest? The DoseRank score also weighs clinical strength, evidence, dose fit and trust — the very cheapest listings rarely hold up everywhere else.
Ready?
The #1 pick is $0.07 a serving.21st Century, Calcium Plus D3, 90 Tablets — in stock at a tracked retailer.
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Frequently asked
21st Century, Calcium Plus D3, 90 Tablets ranks #1 for Bone mineral density with a DoseRank score of 92. The score blends clinical strength, evidence, dose fit, trust signals and value across 9,504 products scored for this outcome.
Vitamin D3 (Cholecalciferol) and Calcium Carbonate are the strongest evidence signals for this outcome.
1 of 2 dosed ingredients land in the studied range. Vitamin D3 (Cholecalciferol) at 20 mcg sits below the studied 800-4000 IU window. DoseRank scores this product's dose fit at 66 out of 100.
21st Century, Calcium Plus D3, 90 Tablets works out at $0.07 per serving. $0.07 per serving — low price tier for this outcome. The cheapest ranked pick here is $0.03 per serving.
No. Retailer links may be affiliate links, but rankings and placement are never paid. Every product is scored by the same public model, and the ranking is recomputed from the underlying product data rather than edited by hand.
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