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Calcium 500 + D3

21st Century
4.8
★ ★ ★ ★ ★
(4233 ratings)
Calcium 500 mg
Product Image
Score96

An incredible value, 400-count supply of natural oyster shell calcium and vitamin D3.

How scoring works
Quantity:400 Tablet(s) • (400 servings)
Goals:
Bone Health

Score 96

An incredible value, 400-count supply of natural oyster shell calcium and vitamin D3.

How scoring works

Also available as

3 options
90 servings Calcium 500 mg • 90 Tablet(s) • 90 servings $5.49 ($0.06 per serving) 600mg • 75 Tablet(s) servings Calcium 600 mg • 75 Tablet(s) • 75 servings $4.99 ($0.06 per serving) 1000mg • 90 Tablet(s) servings Calcium 1000 mg • 90 Tablet(s) • 90 servings $6.21 ($0.06 per serving)
$10.99($0.02 per serving)
iHerb
$ 10.99
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Analysis

Using a large-count bottle helps ensure that you never miss a day of your bone health routine. The 500mg dose is well-calibrated to match how much calcium the gut can process at one time, minimizing mineral waste.

The natural source and the addition of vitamin D3 make this a reliable foundational supplement. It addresses the most basic needs for skeletal mineral density in a very accessible format.

Pros

  • Massive 400-day supply
  • Unbeatable value for money
  • Properly sized 500mg dose
  • Natural mineral source

Cons

  • Allergy risk (shellfish)
  • Missing magnesium and vitamin K
  • Tablets can be somewhat large

Warnings

  • Check for shellfish allergy before use
  • Take with a meal for best digestion

Nutrient quality

88 Highest impact

Inclusion of vitamin D3 enhances the utility of the calcium carbonate source for skeletal support. While bioavailability of the mineral is moderate, the synergistic pairing is appropriate for maintenance.

Ingredient transparency

99 Highest impact

Labeling clearly identifies the oyster shell source and quantifies the active components. Consumer transparency is supported by clear intake instructions and disclosure of excipients.

Customer satisfaction

97 Highest impact

Superior user ratings from a massive demographic confirm the product's reliability and quality. Feedback indicate high satisfaction with the perceived benefits and affordable nature of the supplement.

Value for money

100 Highest impact

Pricing is exceptionally low for a synergistic mineral and vitamin supplement in a bulk format. High serving value makes this a top choice for budget-conscious users seeking skeletal support.

Report analysis

Goals

Bone Health
Impact
High effect
A- Goal FitB Strength of SupportC CoverageA Formula Quality

Oyster shell-derived calcium provides a foundational structural mineral required for maintaining skeletal density and strength. Vitamin D3 is included to maximize the intestinal absorption and transport of calcium to the bone matrix.

The use of carbonate from oyster shells is less bioavailable than organic chelates and requires adequate stomach acid for effectiveness. This formula lacks structural magnesium and signaling cofactors like vitamin K2, which limits its comprehensive skeletal support.

View goal →

Ingredients

IngredientAmount per serving
Vitamin D3 (Cholecalciferol)
 15 mcg
Calcium (Oyster)
 500 mg
Gluten Free Adults 18–50
Report overview
Calcium (Oyster) · 500 mg OverallScore80
C+ Active Ingredient Quality & BioavailabilityB+ Dose, Safety & Label TransparencyA+ Value
This large-count oyster shell calcium supplement provides long-term foundational support for bone density. It offers an ideally sized dose of 500 mg calcium carbonate in each tablet for efficient daily use.
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